ASTM A-710 GRADE B High Performance
Carbon Equivalent 70 ksi Grade Low Temperature Tough Improved Weldability Improved Weatherability Life) Steel Beams used in the construction of the Lake Villa Bridge Page 10: Semi-automatic welding of NUCu 70-lbs at -80°F. Due to its very low carbon equivalent, NUCu 70W (ASTM A710 Grade B) steel generally does
Alternative Fuels Data Center: ASTM Biodiesel Specifications
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), 2002; Level:5 TablesExports(Journal Article)41cloth Documentation DataDepartment of EnergyOn-Farm Biofuel Production Grants The Governor's OfficeVehicleASTM
Biodiesel Progress: ASTM Specifications and 2nd Generation Biodiesel...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
and 2nd Generation Biodiesel Biodiesel Progress: ASTM Specifications and 2nd Generation Biodiesel Presentation given at the 2007 Diesel Engine-Efficiency & Emissions...
Journal of ASTM International, May 2005, Vol. 2, No. 5 Paper ID JAI12375
Motta, Arthur T.
Journal of ASTM International, May 2005, Vol. 2, No. 5 Paper ID JAI12375 Available online at www Conshohocken, PA 19428-2959. #12;JOURNAL OF ASTM INTERNATIONAL2 It is understood that the oxide formed on Zr
Properties of concrete incorporating high volumes of ASTM Class F fly ash
Li, Wei Tung
1995-01-01T23:59:59.000Z
This thesis presents the results of research performed in developing high-volume fly ash (HVFA) concrete incorporating ASTM Type I cement and ASTM Class F fly ash from Big Brown Power Plant of TU Electric, Texas. In HVFA concrete, the proportion...
Properties of concrete incorporating high volumes of ASTM Class F fly ash
Li, Wei Tung
1995-01-01T23:59:59.000Z
This thesis presents the results of research performed in developing high-volume fly ash (HVFA) concrete incorporating ASTM Type I cement and ASTM Class F fly ash from Big Brown Power Plant of TU Electric, Texas. In HVFA concrete, the proportion...
ASTM standards associated with PWR and BWR power plant licensing, operation and surveillance
McElroy, W.N. [Consultants and Technology Services, Richland, WA (United States); McElroy, R.J. [AEA Reactor Services, Harwell (United Kingdom); Gold, R. [Metrology Control Corp., Richland, WA (United States); Lippincott, E.P. [Westinghouse Electric Corp., Pittsburgh, PA (United States); Lowe, A.L. Jr. [BW Nuclear Technologies, Lynchburg, VA (United States)
1994-12-31T23:59:59.000Z
This paper considers ASTM Standards that are available, under revision, and are being considered in support of Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) Nuclear Power Plant (NPP) licensing, regulation, operation, surveillance and life attainment. The current activities of ASTM Committee E10 and its Subcommittees E10.02 and current activities of ASTM Committee E10 and its Subcommittees E10.02 and E10.05 and their Task Groups (TG) are described. A very important aspect of these efforts is the preparation, revision, and balloting of standards identified in the ASTM E706 Standard on Master Matrix for Light Water Reactor (LWR) Pressure Vessel (PV) Surveillance Standards. The current version (E706-87) of the Master Matrix identifies 21 ASTM LWR physics-dosimetry-metallurgy standards for Reactor Pressure Vessel (RPV) and Support Structure (SS) surveillance programs, whereas, for the next revision 34 standards are identified. The need for national and international coordination of Standards Technology Development, Transfer and Training (STDTT) is considered in this and other Symposium papers that address specific standards related physics-dosimetry-metallurgy issues. 69 refs.
American Society for Quality Procedures for Detecting Outlying Observations in Samples
Masci, Frank
Statistical Association and American Society for Quality Stable URL: http://www.jstor.org/stable/1266761@jstor.org. American Statistical Association and American Society for Quality are collaborating with JSTOR to digitize, Committee E-ll on Statistical Methods, The American Society for Testing Materials (ASTM). This work
Fultineer, R.D. Jr.; Mitchell, J.R.
1999-07-01T23:59:59.000Z
There are many composite wrapped pressure vessels in service. These containers are most widely used for gas storage in natural gas vehicles (NGV). A standard has been developed for the testing of these vessels by the subcommittee ASTM E07.04.03 Acoustic Emission (AE) applications. The AE test method is supported by both field test data and laboratory destructive testing. The test method describes a global volumetric testing technique which is offered as an alternative to the current practice of visual inspection.
Impact of ASTM Standard E722 update on radiation damage metrics.
DePriest, Kendall Russell
2014-06-01T23:59:59.000Z
The impact of recent changes to the ASTM Standard E722 is investigated. The methodological changes in the production of the displacement kerma factors for silicon has significant impact for some energy regions of the 1-MeV(Si) equivalent fluence response function. When evaluating the integral over all neutrons energies in various spectra important to the SNL electronics testing community, the change in the response results in an increase in the total 1-MeV(Si) equivalent fluence of 2 7%. Response functions have been produced and are available for users of both the NuGET and MCNP codes.
Dynamic Fracture Initiation Toughness of ASTM A533, Grade B Steel Plate
Graham, S.M.; Link, R.E.
1999-05-01T23:59:59.000Z
The dynamic fracture toughness of an ASTM A533, Grade B steel plate was determined at several temperatures in the ductile-brittle transition region. Crack-tip loading rates ranged from approximately 10(sup3) to 10(sup5) MPa m/s. The fracture toughness was shown to decrease with increased loading rate. The dynamic fracture toughness was compared with results from previous investigations, and it was shown that the decrease in toughness due to increased loading rate at the highest test temperature was not as severe as reported in previous investigations. It was also shown that the reference temperature. T(sub0) was better index of the fracture toughness vs. temperature relationship than the nil-ductility temperature, RT(subNDT), for this material.
Processing and properties of superclean ASTM A508 Cl. 4 forgings
Hinkel, A.V.; Handerhan, K.J. [Ellwood City Forge, PA (United States); Manzo, G.J. [Ellwood Group Inc., PA (United States). Steel Division; Simkins, G.P. [Westinghouse Electric Corp., Pittsburgh, PA (United States)
1988-12-31T23:59:59.000Z
Steels with improved resistance to temper embrittlement are now being produced using ``superclean`` steelmaking technology. This technology involves the use of scrap control, proper electric arc furnace and ladle refining furnace practices to produce steel with very low Mn, Si, P, S and other residual impurities such as Sn, As and Sb. This technology has been applied on a production basis to modified ASTM A508 Cl- 4 material intended for high temperature pressure vessel forgings. Processing and properties of this superclean material are reviewed. In addition, the cleanliness and mechanical properties are compared to conventionally melted A508 Cl. 4 material. The ``superclean`` A508 Cl. 4 mod. was found to meet all specification requirements. In addition, the superclean material was found to possess superior upper shelf CVN properties, a lower FATT{sub 50} and NDTT, along with superior microcleanliness compared to conventional material. Finally, the superclean material was found to be immune to temper embrittlement based on the short-term embrittlement treatments examined.
Suresh, Sri Vishnu Chaitanya Guptha
2014-08-14T23:59:59.000Z
in 1980s in the Australian laboratories. Former TAMU students had built a lightweight Indian unbalanced and balanced bond wrench. An Australian bond wrench was manufactured in 2011 and subsequently in 2012 an ASTM C 1072 Bond Wrench was developed...
Massive gravity from bimetric gravity
Baccetti, Valentina; Visser, Matt
2012-01-01T23:59:59.000Z
We discuss the subtle relationship between so-called massive gravity (that is, gravity incorporating a non-zero graviton mass) and bimetric gravity, focussing particularly on the manner in which massive gravity may be viewed as a suitable limit of bimetric gravity. The limiting procedure is more delicate than currently appreciated, and in particular, in a cosmological context can lead to an interesting interplay between the "background" and "foreground" metrics. The fact that in bimetric theories one always has two sets of metric equations of motion, one for each metric, continues to have an effect even in the massive gravity limit. Thus, solutions of bimetric gravity in the limit of vanishing kinetic term are also solutions of massive gravity, but the contrary statement is not necessarily true.
Uptakes of Cs and Sr on San Joaquin soil measured following ASTM method C1733.
Ebert, W.L.; Petri, E.T. (Chemical Sciences and Engineering Division)
2012-04-04T23:59:59.000Z
Series of tests were conducted following ASTM Standard Procedure C1733 to evaluate the repeatability of the test and the effects of several test parameters, including the solution-to-soil mass ratio, test duration, pH, and the concentrations of contaminants in the solution. This standard procedure is recommended for measuring the distribution coefficient (K{sub d}) of a contaminant in a specific soil/groundwater system. One objective of the current tests was to identify experimental conditions that can be used in future interlaboratory studies to determine the reproducibility of the test method. This includes the recommendation of a standard soil, the range of contaminant concentrations and solution matrix, and various test parameters. Quantifying the uncertainty in the distribution coefficient that can be attributed to the test procedure itself allows the differences in measured values to be associated with differences in the natural systems being studied. Tests were conducted to measure the uptake of Cs and Sr dissolved as CsCl and Sr(NO{sub 3}){sub 2} in a dilute NaHCO{sub 3}/SiO{sub 2} solution (representing contaminants in a silicate groundwater) by a NIST standard reference material of San Joaquin soil (SRM 2709a). Tests were run to measure the repeatability of the method and the sensitivity of the test response to the reaction time, the mass of soil used (at a constant soil-to-solution ratio), the solution pH, and the contaminant concentration. All tests were conducted in screw-top Teflon vessels at 30 C in an oven. All solutions were passed through a 0.45-{mu}m pore size cellulose acetate membrane filter and stabilized with nitric acid prior to analysis with inductively-coupled plasma mass spectrometry (ICP-MS). Scoping tests with soil in demineralized water resulted in a solution pH of about 8.0 and the release of small amounts of Sr from the soil. Solutions were made with targeted concentrations of 1 x 10{sup -6} m, 1 x 10{sup -5} m, 2.5 x 10{sup -5} m, 5 x 10{sup -5} m, 1 x 10{sup -4} m, and 5 x 10{sup -4} m to measure the effects of the Cs and Sr concentrations on their uptake by the soil. The pH values of all solutions were adjusted to about pH 8.5 so that the effects of pH and concentration could be measured separately. The 1 x 10{sup -4} m solutions were used to measure the repeatability of the test and the effects of duration, scale, and imposed pH on the test response.
Lujan, Richard E. (Santa Fe, NM)
2001-01-01T23:59:59.000Z
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.
Narrow groove gas tungsten arc welding of ASTM A508 Class 4 steel for improved toughness properties
Penik, M.A. Jr. [Rensselaer Polytechnic Inst., Troy, NY (United States)
1997-04-01T23:59:59.000Z
Welding of heavy section steel has traditionally used the automatic submerged arc welding (ASAW) process because of the high deposition rates achievable. However, the properties, particularly fracture toughness, of the weld are often inferior when compared to base material. This project evaluated the use of narrow groove gas tungsten arc welding (GTAW) to improve weld material properties. The welding procedures were developed for ASTM A508 Class 4 base material using a 1% Ni filler material complying to AWS Specification A.23-90-EF3-F3-N. A narrow groove joint preparation was used in conjunction with the GTAW process so competitive fabrication rates could be achieved when compared to the ASAW process. Weld procedures were developed to refine weld substructure to achieve better mechanical properties. Two heaters of weld wire were used to examine the effects of minor filler metal chemistry differences on weld mechanical properties. Extensive metallographic evaluations showed excellent weld quality with a refined microstructure. Chemical analysis of the weld metal showed minimal weld dilution by the base metal. Mechanical testing included bend and tensile tests to ensure weld quality and strength. A Charpy impact energy curve versus temperature and fracture toughness curve versus temperature were developed for each weld wire heat. Results of fracture toughness and Charpy impact testing indicated an improved transition temperature closer to that of the base material properties.
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), 2002; Level:5(Million Cubic Feet) Oregon (Including Vehicle Fuel) (Million Cubic Feet)sets safety record |PersonalPhotos7 Policy2 (2010) 095002 (17pp)2Porterfield
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), 2002; Level:5 TablesExports(Journal Article) |govInstrumentsmfrirtA Journey Inside the Complex(MARSSIM)K. Coffman2 PhotonsPolicy | NationalOffice ofU.S.
B. L. Hu
1999-02-22T23:59:59.000Z
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.
Rong-Jia Yang
2014-09-11T23:59:59.000Z
If we assume that the source of thermodynamic system, $\\rho$ and $p$, are also the source of gravity, thermal quantities, such as entropy, temperature, and chemical potential, can induce effects of gravity, or gravity can induce thermal effects. We find only for systems with constant temperature and zero chemical potential, gravity can be seen as an entropic force. The case for Newtonian approximation is discussed.
Quantization of Emergent Gravity
Hyun Seok Yang
2014-12-24T23:59:59.000Z
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.
Felix M. Lev
2010-05-16T23:59:59.000Z
We consider a possibility that gravity is not an interaction but a manifestation of a symmetry based on a Galois field.
Particle Dynamics And Emergent Gravity
Amir H. Fatollahi
2008-05-08T23:59:59.000Z
The emergent gravity proposal is examined within the framework of noncommutative QED/gravity correspondence from particle dynamics point of view.
1 American Studies AMERICAN STUDIES
Vertes, Akos
1 American Studies AMERICAN STUDIES An innovative department with 15 core faculty and 12 affiliated of culture, ideas and religious beliefs; the development and transformation of public cultures and spaces. Topics include the civil rights movement, the student movement, the Vietnam War, and the counterculture
Exercise in artificial gravity
Edmonds, Jessica Leigh
2005-01-01T23:59:59.000Z
Artificial gravity provided by short radius centrifugation is considered a promising countermeasure to the deleterious physiological effects of microgravity during long-duration space flight. We investigated the feasibility ...
Time Gravity and Quantum Mechanics
W. G. Unruh
1993-12-17T23:59:59.000Z
Time plays different roles in quantum mechanics and gravity. These roles are examined and the problems that the conflict in the roles presents for quantum gravity are briefly summarised.
Polchinski, Joseph [Kavli Institute for Theoretical Physics
2010-09-01T23:59:59.000Z
Gauge theories, which describe the particle interactions, are well understood, while quantum gravity leads to many puzzles. Remarkably, in recent years we have learned that these are actually dual, the same system written in different variables. On the one hand, this provides our most precise description of quantum gravity, resolves some long-standing paradoxes, and points to new principles. On the other, it gives a new perspective on strong interactions, with surprising connections to other areas of physics. I describe these ideas, and discuss current and future directions.
Introduction Basics of gravity theory
Visser, Matt
Introduction Basics of gravity theory Actions and Field Equations Phenomenology Discussion;Introduction Basics of gravity theory Actions and Field Equations Phenomenology Discussion and Conclusions Victoria U of Wellington - Feb 2nd 2009 #12;Introduction Basics of gravity theory Actions and Field
Massive gravity as a limit of bimetric gravity
Martin-Moruno, Prado; Visser, Matt
2013-01-01T23:59:59.000Z
Massive gravity may be viewed as a suitable limit of bimetric gravity. The limiting procedure can lead to an interesting interplay between the "background" and "foreground" metrics in a cosmological context. The fact that in bimetric theories one always has two sets of metric equations of motion continues to have an effect even in the massive gravity limit. Thus, solutions of bimetric gravity in the limit of vanishing kinetic term are also solutions of massive gravity, but the contrary statement is not necessarily true.
The determination of the moisture absorption characteristics of lightweight concrete aggregates
Bryant, Julian Stephen
1959-01-01T23:59:59.000Z
" ], 2 120 " 1. 3 1 dey 2, 9 3, 6 3 II 4. 2 3 II 4. 1 3 tl 4. 0 APPENDIX B STANDARD METHOD OF TEST FOR SPECIFIC GRAVITY AND ABSORPTION OF COARSE AGGREGATE ASTM Designation: C 127 - 42 ~Sco e l. (a) This method of test is intended for use... gravity as defined in the Standard Defini- tions of Terms Relating to Specific Gravity (ASTM Designation: E 12) of the American Society for Testing Materials, shall be calculated from the following formula: A Apparent sp. gr. . ~ . A - C 46. A~bt1...
Gravity on Conformal Superspace
Bryan Kelleher
2003-11-11T23:59:59.000Z
The configuration space of general relativity is superspace - the space of all Riemannian 3-metrics modulo diffeomorphisms. However, it has been argued that the configuration space for gravity should be conformal superspace - the space of all Riemannian 3-metrics modulo diffeomorphisms and conformal transformations. Taking this conformal nature seriously leads to a new theory of gravity which although very similar to general relativity has some very different features particularly in cosmology and quantisation. It should reproduce the standard tests of general relativity. The cosmology is studied in some detail. The theory is incredibly restrictive and as a result admits an extremely limited number of possible solutions. The problems of the standard cosmology are addressed and most remarkably the cosmological constant problem is resolved in a natural way. The theory also has several attractive features with regard to quantisation particularly regarding the problem of time.
Iver Brevik
2012-11-23T23:59:59.000Z
A bulk viscosity is introduced in the formalism of modified gravity. It is shown that, on the basis of a natural scaling law for the viscosity, a simple solution can be found for quantities such as the Hubble parameter and the energy density. These solutions may incorporate a viscosity-induced Big Rip singularity. By introducing a phase transition in the cosmic fluid, the future singularity can nevertheless in principle be avoided.
Lie algebraic noncommutative gravity
Banerjee, Rabin; Samanta, Saurav [S. N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake, Kolkata-700098 (India); Mukherjee, Pradip [Presidency College, 86/1 College Street, Kolkata-700073, West-Bengal (India)
2007-06-15T23:59:59.000Z
We exploit the Seiberg-Witten map technique to formulate the theory of gravity defined on a Lie algebraic noncommutative space-time. Detailed expressions of the Seiberg-Witten maps for the gauge parameters, gauge potentials, and the field strengths have been worked out. Our results demonstrate that notwithstanding the introduction of more general noncommutative structure there is no first order correction, exactly as happens for a canonical (i.e. constant) noncommutativity.
Gravity, Dimension, Equilibrium, & Thermodynamics
Jerome Perez
2006-03-30T23:59:59.000Z
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.
Koyama, Kazuya
2015-01-01T23:59:59.000Z
Einstein's theory of General Relativity (GR) is tested accurately within the local universe i.e., the Solar System, but this leaves open the possibility that it is not a good description at the largest scales in the Universe. The standard model of cosmology assumes GR as the theory to describe gravity on all scales. In 1998, astronomers made the surprising discovery that the expansion of the Universe is accelerating, not slowing down. This late-time acceleration of the Universe has become the most challenging problem in theoretical physics. Within the framework of GR, the acceleration would originate from an unknown dark energy. Alternatively, it could be that there is no dark energy and GR itself is in error on cosmological scales. The standard model of cosmology is based on a huge extrapolation of our limited knowledge of gravity. This discovery of the late time acceleration of the Universe may require us to revise the theory of gravity and the standard model of cosmology based on GR. We will review recent ...
Lifshitz Gravity for Lifshitz Holography
Tom Griffin; Petr Horava; Charles M. Melby-Thompson
2012-11-20T23:59:59.000Z
We argue that Horava-Lifshitz (HL) gravity provides the minimal holographic dual for Lifshitz-type field theories with anisotropic scaling and dynamical exponent z. First we show that Lifshitz spacetimes are vacuum solutions of HL gravity, without need for additional matter. Then we perform holographic renormalization of HL gravity, and show how it reproduces the full structure of the z=2 anisotropic Weyl anomaly in dual field theories in 2+1 dimensions, while its minimal relativistic gravity counterpart yields only one of two independent central charges in the anomaly.
Ning Wu
2005-10-01T23:59:59.000Z
It is well-known that energy-momentum is the source of gravitational field. For a long time, it is generally believed that only stars with huge masses can generate strong gravitational field. Based on the unified theory of gravitational interactions and electromagnetic interactions, a new mechanism of the generation of gravitational field is studied. According to this mechanism, in some special conditions, electromagnetic energy can be directly converted into gravitational energy, and strong gravitational field can be generated without massive stars. Gravity impulse found in experiments is generated by this mechanism.
Lubricated viscous gravity currents
Kowal, Katarzyna N.; Worster, M. Grae
2015-02-10T23:59:59.000Z
. The only previous work on two-layer gravity currents (Woods & Mason 2000) involved flow in a porous medium and so did not feature viscous coupling between the layers. We have performed a series of laboratory experiments using golden syrup lubricated... and velocity are related linearly by ui ? h µl ?i. (2.20) This is a sliding law in which the sliding coefficient depends on the lower film thickness. It has a similar structure to the sliding law ? = Cu1/n used in many glaciological stud- ies (Weertman 1957...
K. H. Mariwalla
2002-05-28T23:59:59.000Z
Basis and limitations of singularity theorems for Gravity are examined. As singularity is a critical situation in course of time, study of time paths, in full generality of Equivalence principle, provides two mechanisms to prevent singularity. Resolution of singular Time translation generators into space of its orbits, and essential higher dimensions for Relativistic particle interactions has facets to resolve any real singularity problem. Conceptually, these varied viewpoints have a common denominator: arbitrariness in the definition of `energy' intrinsic to the space of operation in each case, so as to render absence of singularity a tautology for self-consistency of the systems.
Reduced models for quantum gravity
T. Thiemann
1999-10-04T23:59:59.000Z
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.
AdS Chern-Simons Gravity induces Conformal Gravity
Rodrigo Aros; Danilo E. Diaz
2013-12-25T23:59:59.000Z
The leitmotif of this paper is the question of whether four- and higher even-dimensional Conformal Gravities do have a Chern-Simons pedigree. We show that Weyl gravity can be obtained as dimensional reduction of a five-dimensional Chern-Simons action for a suitable (gauged-fixed, tractor-like) five-dimensional AdS connection. The gauge-fixing and dimensional reduction program admits a readily generalization to higher dimensions for the case of certain conformal gravities obtained by contractions of the Weyl tensor.
Natural Inflation and Quantum Gravity
Anton de la Fuente; Prashant Saraswat; Raman Sundrum
2015-01-29T23:59:59.000Z
Cosmic Inflation provides an attractive framework for understanding the early universe and the cosmic microwave background. It can readily involve energies close to the scale at which Quantum Gravity effects become important. General considerations of black hole quantum mechanics suggest nontrivial constraints on any effective field theory model of inflation that emerges as a low-energy limit of quantum gravity, in particular the constraint of the Weak Gravity Conjecture. We show that higher-dimensional gauge and gravitational dynamics can elegantly satisfy these constraints and lead to a viable, theoretically-controlled and predictive class of Natural Inflation models.
Riding Gravity Away from Doomsday
Ashoke Sen
2015-03-27T23:59:59.000Z
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.
Riding Gravity Away from Doomsday
Sen, Ashoke
2015-01-01T23:59:59.000Z
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.
Gravity as an Entropic Phenomenon
Abhiram Chivukula
2010-11-19T23:59:59.000Z
The unification of gravity with the three other forces has been an important goal of physics for some time now, because a quantum theory of gravity is necessary to explain the universe at its earliest moments. Its pursuit has largely assumed gravity's independent existence, but E. Verlinde proposed that gravity is not a fundamental force but a macroscopic phenomenon that emerges as a result of thermodynamic principles applied to the information of mass distributions. Under this framework we consider the roles played by quantum microstates, entanglement, information theory, the AdS/CFT Correspondence, and String Theory in general. We also ask whether Verlinde's proposal suggests that action principles should be thermodynamic in nature.
Gravity as an Entropic Phenomenon
Chivukula, Abhiram
2010-01-01T23:59:59.000Z
The unification of gravity with the three other forces has been an important goal of physics for some time now, because a quantum theory of gravity is necessary to explain the universe at its earliest moments. Its pursuit has largely assumed gravity's independent existence, but E. Verlinde proposed that gravity is not a fundamental force but a macroscopic phenomenon that emerges as a result of thermodynamic principles applied to the information of mass distributions. Under this framework we consider the roles played by quantum microstates, entanglement, information theory, the AdS/CFT Correspondence, and String Theory in general. We also ask whether Verlinde's proposal suggests that action principles should be thermodynamic in nature.
Testing Gravity Theories Using Stars
Jeremy Sakstein; Bhuvnesh Jain; Vinu Vikram
2014-09-12T23:59:59.000Z
Modified theories of gravity have received a renewed interest due to their ability to account for the cosmic acceleration. In order to satisfy the solar system tests of gravity, these theories need to include a screening mechanism that hides the modifications on small scales. One popular and well-studied theory is chameleon gravity. Our own galaxy is necessarily screened, but less dense dwarf galaxies may be unscreened and their constituent stars can exhibit novel features. In particular, unscreened stars are brighter, hotter and more ephemeral than screened stars in our own galaxy. They also pulsate with a shorter period. In this essay, we exploit these new features to constrain chameleon gravity to levels three orders of magnitude lower the previous measurements. These constraints are currently the strongest in the literature.
Critical Gravity in Four Dimensions
Lue, H. [China Economics and Management Academy, Central University of Finance and Economics, Beijing 100081 (China); Institute for Advanced Study, Shenzhen University, Nanhai Avenue 3688, Shenzhen 518060 (China); Pope, C. N. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States); DAMTP, Centre for Mathematical Sciences, Cambridge University, Wilberforce Road, Cambridge CB3 OWA (United Kingdom)
2011-05-06T23:59:59.000Z
We study four-dimensional gravity theories that are rendered renormalizable by the inclusion of curvature-squared terms to the usual Einstein action with a cosmological constant. By choosing the parameters appropriately, the massive scalar mode can be eliminated and the massive spin-2 mode can become massless. This ''critical'' theory may be viewed as a four-dimensional analogue of chiral topologically massive gravity, or of critical 'new massive gravity' with a cosmological constant, in three dimensions. We find that the on-shell energy for the remaining massless gravitons vanishes. There are also logarithmic spin-2 modes, which have positive energy. The mass and entropy of standard Schwarzschild-type black holes vanish. The critical theory might provide a consistent toy model for quantum gravity in four dimensions.
Quantum Gravity: Motivations and Alternatives
Reiner Hedrich
2009-08-03T23:59:59.000Z
The mutual conceptual incompatibility between GR and QM/QFT is generally seen as the most essential motivation for the development of a theory of Quantum Gravity (QG). It leads to the insight that, if gravity is a fundamental interaction and QM is universally valid, the gravitational field will have to be quantized, not at least because of the inconsistency of semi-classical theories of gravity. If this means to quantize GR, its identification of the gravitational field with the spacetime metric has to be taken into account. And the resulting quantum theory has to be background-independent. This can not be achieved by means of quantum field theoretical procedures. More sophisticated strategies have to be applied. One of the basic requirements for such a quantization strategy is that the resulting quantum theory has GR as a classical limit. - However, should gravity not be a fundamental, but an residual, emergent interaction, it could very well be an intrinsically classical phenomenon. Should QM be nonetheless universally valid, we had to assume a quantum substrate from which gravity would result as an emergent classical phenomenon. And there would be no conflict with the arguments against semi-classical theories, because there would be no gravity at all on the substrate level. The gravitational field would not have any quantum properties, and a quantization of GR would not lead to any fundamental theory. The objective of a theory of 'QG' would instead be the identification of the quantum substrate from which gravity results. - The paper tries to give an overview over the main options for theory construction in the field of QG. Because of the still unclear status of gravity and spacetime, it pleads for the necessity of a plurality of conceptually different approaches to QG.
D. Fargion
2005-11-23T23:59:59.000Z
The present gravitational wave detectors are reaching lowest metric deviation fields able to detect galactic and extra-galactic gravitational waves, related to Supernova explosions up to Virgo cluster. The same gravitational wave detector are nevertheless almost able to reveal, in principle, near field Newtonian gravitational perturbations due to fast huge mass displacements as the ones occurring during largest Earth-Quake or Tsunami as the last on 26nd December 2004 in Asiatic area. Virgo and Ligo detector are unfortunately recording on high frequencies (above tens Hz) while the signal of the Tsunami lay at much lower range (below 0.1 Hz). Nevertheless prompt gravitational near field deformation by the Tsunami might reach the future LISA threshold sensitivity and frequency windows if such an array is located nearby (3000-10000) km distances. Unfortunately the present LISA system should be located at Lagrange point too far (1.5 million km. far away). We note however that the later continental mass rearrangement and their gravitational field assessment on Earth must induce, for Richter Magnitude 9-like Tsunami, a different terrestrial inertia momentum and a different principal rotation axis. In conclusion we remind that gravitational geodetic deviation on new precise satellites (GOCE 2006), assisted by GPS network, might nevertheless reach in the near future the needed threshold and accuracy to reveal Tsunami by their prompt tidal gravity field deviations . An array of such geoid detector maybe correlated with LISA-like satellite on Earth orbits may offer the fastest alarm system.
Conformal Lifshitz Gravity from Holography
Tom Griffin; Petr Horava; Charles M. Melby-Thompson
2012-04-03T23:59:59.000Z
We show that holographic renormalization of relativistic gravity in asymptotically Lifshitz spacetimes naturally reproduces the structure of gravity with anisotropic scaling: The holographic counterterms induced near anisotropic infinity take the form of the action for gravity at a Lifshitz point, with the appropriate value of the dynamical critical exponent $z$. In the particular case of 3+1 bulk dimensions and $z=2$ asymptotic scaling near infinity, we find a logarithmic counterterm, related to anisotropic Weyl anomaly of the dual CFT, and show that this counterterm reproduces precisely the action of conformal gravity at a $z=2$ Lifshitz point in 2+1 dimensions, which enjoys anisotropic local Weyl invariance and satisfies the detailed balance condition. We explain how the detailed balance is a consequence of relations among holographic counterterms, and point out that a similar relation holds in the relativistic case of holography in $AdS_5$. Upon analytic continuation, analogous to the relativistic case studied recently by Maldacena, the action of conformal gravity at the $z=2$ Lifshitz point features in the ground-state wavefunction of a gravitational system with an interesting type of spatial anisotropy.
Gauge Theory of Quantum Gravity
J. W. Moffat
1994-01-04T23:59:59.000Z
A gauge theory of quantum gravity is formulated, in which an internal, field dependent metric is introduced which non-linearly realizes the gauge fields on the non-compact group $SL(2,C)$, while linearly realizing them on $SU(2)$. Einstein's $SL(2,C)$ invariant theory of gravity emerges at low energies, since the extra degrees of freedom associated with the quadratic curvature and the internal metric only dominate at high energies. In a fixed internal metric gauge, only the the $SU(2)$ gauge symmetry is satisfied, the particle spectrum is identified and the Hamiltonian is shown to be bounded from below. Although Lorentz invariance is broken in this gauge, it is satisfied in general. The theory is quantized in this fixed, broken symmetry gauge as an $SU(2)$ gauge theory on a lattice with a lattice spacing equal to the Planck length. This produces a unitary and finite theory of quantum gravity.
Tian, David Wenjie
2015-01-01T23:59:59.000Z
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}\
de Sitter gravity/Euclidean conformal gravity correspondence
Chatterjee, Atreya
2015-01-01T23:59:59.000Z
The holographic dual of a gravitational theory around the de Sitter background is argued to be a Euclidean conformal gravity theory in one fewer dimensions. The measure for the holographic theory naturally includes a sum over topologies as well as conformal structures.
Emergent 4D Gravity from Matrix Models
Harold Steinacker
2007-12-19T23:59:59.000Z
Recent progress in the understanding of gravity on noncommutative spaces is discussed. A gravity theory naturally emerges from matrix models of noncommutative gauge theory. The effective metric depends on the dynamical Poisson structure, absorbing the degrees of freedom of the would-be U(1) gauge field. The gravity action is induced upon quantization.
Intrusive gravity currents in two-layer
Flynn, Morris R.
Intrusive gravity currents in two-layer stratified media Morris R. Flynn & Paul F. Linden Dept.avalanche.org/pictures #12;· `Microbursts' pose a non-trivial threat to airplane safety Introduction Impacts on human health;· Whereas gravity currents travel along a solid boundary, intrusive gravity currents or intrusions propagate
ASTM A-710 GRADE B High Performance
Carbon Equivalent 70 ksi Grade Low Temperature Tough Improved Weldability Improved Weatherability Life Properties Corrosion Welding Selected Publications Contact 3 4 5 6 7, 8 7 9 9 DISCLAIMER Front Cover: Bridge) Steel Beams used in the construction of the Lake Villa Bridge Page 10: Semi-automatic welding of NUCu 70
Cosmological Hints of Modified Gravity ?
Eleonora Di Valentino; Alessandro Melchiorri; Joseph Silk
2015-09-24T23:59:59.000Z
The recent measurements of Cosmic Microwave Background temperature and polarization anisotropies made by the Planck satellite have provided impressive confirmation of the $\\Lambda$CDM cosmological model. However interesting hints of slight deviations from $\\Lambda$CDM have been found, including a $95 \\%$ c.l. preference for a "modified gravity" structure formation scenario. In this paper we confirm the preference for a modified gravity scenario from Planck 2015 data, find that modified gravity solves the so-called $A_{lens}$ anomaly in the CMB angular spectrum, and constrains the amplitude of matter density fluctuations to $\\sigma_8=0.815_{-0.048}^{+0.032}$, in better agreement with weak lensing constraints. Moreover, we find a lower value for the reionization optical depth of $\\tau=0.059\\pm0.020$ (to be compared with the value of $\\tau= 0.079 \\pm 0.017$ obtained in the standard scenario), more consistent with recent optical and UV data. We check the stability of this result by considering possible degeneracies with other parameters, including the neutrino effective number, the running of the spectral index and the amount of primordial helium. The indication for modified gravity is still present at about $95\\%$ c.l., and could become more significant if lower values of $\\tau$ were to be further confirmed by future cosmological and astrophysical data.
Liouville quantum gravity and KPZ
Duplantier, Bertrand
Consider a bounded planar domain D, an instance h of the Gaussian free field on D, with Dirichlet energy ... and a constant 0[less than or equal to]?<2. The Liouville quantum gravity measure on D is the weak limit as ...
Thomas Rauch
2006-07-11T23:59:59.000Z
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.
Quantum Gravity and Precision Tests
C. P. Burgess
2006-06-24T23:59:59.000Z
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.
AMERICAN ANTHROPOLOGIST Public Anthropology
Illinois at Chicago, University of
AMERICAN ANTHROPOLOGIST Public Anthropology 2012 Public Anthropology Year in Review: Actually, Rick a torrent of criticism from anthropologists, including an online response by #12;Year in Review: Public
Precedents in African American architecture
Sass, Lawrence
1994-01-01T23:59:59.000Z
As a sub-sets of American culture, African Americans have not been able to offer culturally specific architectural elements to the design process because the history of African American form and space has not been recognized ...
American Institute of Aeronautics Astronautics
American Institute of Aeronautics Astronautics Study Cylindrical Thruster Low Power Space scaling of magnetic circuit leaves almost no magnetic Copyright American Institute Aeronautics; American Institute of Aeronautics Astronautics ability coaxial thrusters achieve performance moderate power
New Branches of Massive Gravity
Comelli, Denis; Koyama, Kazuya; Pilo, Luigi; Tasinato, Gianmassimo
2015-01-01T23:59:59.000Z
The basic building block for Lorentz invariant and ghost free massive gravity is the square root of the combination $g^{-1}\\eta\\,$, where $g^{-1}$ is the inverse of the physical metric and $\\eta$ is a reference metric. Since the square root of a matrix is not uniquely defined, it is possible to have physically inequivalent potentials corresponding to different branches. We show that around Minkowski background the only perturbatively well defined branch is the potential proposed by de Rham, Gabadadze and Tolley. On the other hand, if Lorentz symmetry is broken spontaneously, other potentials exist with a standard perturbative expansion. We show this explicitly building new Lorentz invariant, ghost-free massive gravity potentials for theories that in the background preserve rotational invariance, but break Lorentz boosts.
Hybrid metric-Palatini gravity
Capozziello, Salvatore; Koivisto, Tomi S; Lobo, Francisco S N; Olmo, Gonzalo J
2015-01-01T23:59:59.000Z
Recently, the phenomenology of f(R) gravity has been scrutinized motivated by the possibility to account for the self-accelerated cosmic expansion without invoking dark energy sources. Besides, this kind of modified gravity is capable of addressing the dynamics of several self-gravitating systems alternatively to the presence of dark matter. It has been established that both metric and Palatini versions of these theories have interesting features but also manifest severe and different downsides. A hybrid combination of theories, containing elements from both these two formalisms, turns out to be also very successful accounting for the observed phenomenology and is able to avoid some drawbacks of the original approaches. This article reviews the formulation of this hybrid metric-Palatini approach and its main achievements in passing the local tests and in applications to astrophysical and cosmological scenarios, where it provides a unified approach to the problems of dark energy and dark matter.
Quantum gravity without Lorentz invariance
Sotiriou, Thomas P; Weinfurtner, Silke
2009-01-01T23:59:59.000Z
There has been a significant surge of interest in Horava's model for 3+1 dimensional quantum gravity, this model being based on anisotropic scaling at a z=3 Lifshitz point. Horava's model, and its variants, show dramatically improved ultra-violet behaviour at the cost of exhibiting violation of Lorentz invariance at ultra-high momenta. Following up on our earlier note, [arXiv:0904.4464 [hep-th
Cosmological Hints of Modified Gravity ?
Di Valentino, Eleonora; Silk, Joseph
2015-01-01T23:59:59.000Z
The recent measurements of Cosmic Microwave Background temperature and polarization anisotropies made by the Planck satellite have provided impressive confirmation of the $\\Lambda$CDM cosmological model. However interesting hints of slight deviations from $\\Lambda$CDM have been found, including a $95 \\%$ c.l. preference for a "modified gravity" structure formation scenario. In this paper we confirm the preference for a modified gravity scenario from Planck 2015 data, find that modified gravity solves the so-called $A_{lens}$ anomaly in the CMB angular spectrum, and constrains the amplitude of matter density fluctuations to $\\sigma_8=0.815_{-0.048}^{+0.032}$, in better agreement with weak lensing constraints. Moreover, we find a lower value for the reionization optical depth of $\\tau=0.059\\pm0.020$ (to be compared with the value of $\\tau= 0.079 \\pm 0.017$ obtained in the standard scenario), more consistent with recent optical and UV data. We check the stability of this result by considering possible degeneraci...
Supersymmetry and Gravity in Noncommutative Field Theories
Victor O. Rivelles
2003-05-14T23:59:59.000Z
We discuss the renormalization properties of noncommutative supersymmetric theories. We also discuss how the gauge field plays a role similar to gravity in noncommutative theories.
Moore honored with American Statistical Association award
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
American Statistical Association Award Moore honored with American Statistical Association award Lisa Moore is the recipient of the 2013 Don Owen Award presented by the American...
Counterterms in Massive Gravity Theory
Cao, Li-Ming
2015-01-01T23:59:59.000Z
We derived local boundary counterterms in massive gravity theory with a negative cosmological constant in four dimensions. With these counterterms at hand we analyzed the properties of the boundary field theory in the context of AdS/CFT duality by calculating the boundary stress energy tensor. The calculation shows that the boundary stress energy tensor is conserved, and momentum dissipation might occur on the level of linear response only. We also calculated the thermodynamic quantities and the boundary stress energy tensor for a specific type of solutions. The thermodynamic potentials agree with the results of literature up to some constants which can be removed by adding finite counterterms.
Gravity Techniques | Open Energy Information
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 DeliciousPlasmaP a g eWorks -09-0018-CX Jump to:DasaValleyEnergy InformationGranville Baird JumpGravity Techniques
Enterprise Assessments, Hanford Site K-West Annex Facility Constructio...
Office of Environmental Management (EM)
ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials International AWS American Welding Society CFR Code of Federal Regulations CGD...
Center for Gravity, Electrical & Magnetic Studies
Center for Gravity, Electrical & Magnetic Studies Colorado School of Mines CGEM Thesis Improving Golden, CO 80401 http://www.geophysics.mines.edu/cgem #12;Center for Gravity, Electrical & Magnetic topic stems from the recent use of multiple magnetometers, which allows for measurements of magnetic
Horava-Lifshitz gravity with detailed balance
Daniele Vernieri; Thomas P. Sotiriou
2012-12-18T23:59:59.000Z
Horava-Lifshitz gravity with "detailed balance" but without the projectability assumption is discussed. It is shown that detailed balance is quite efficient in limiting the proliferation of couplings in Horava-Lifshitz gravity, and that its implementation without the projectability assumption leads to a theory with sensible dynamics. However, the (bare) cosmological constant is restricted to be large and negative.
Reconstruction of Einstein-Aether Gravity from other Modified Gravity Models
Chayan Ranjit; Ujjal Debnath
2014-09-08T23:59:59.000Z
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.
Threat Mitigation: The Gravity Tractor
Russell Schweickart; Clark Chapman; Dan Durda; Piet Hut
2006-08-15T23:59:59.000Z
The Gravity Tractor (GT) is a fully controlled asteroid deflection concept using the mutual gravity between a robotic spacecraft and an asteroid to slowly accelerate the asteroid in the direction of the "hovering" spacecraft. Based on early warning, provided by ground tracking and orbit prediction, it would be deployed a decade or more prior to a potential impact. Ion engines would be utilized for both the rendezvous with the asteroid and the towing phase. Since the GT does not dock with or otherwise physically contact the asteroid during the deflection process there is no requirement for knowledge of the asteroid's shape, composition, rotation state or other "conventional" characteristics. The GT would first reduce the uncertainty in the orbit of the asteroid via Earth tracking of its radio transponder while station keeping with the asteroid. If, after analysis of the more precise asteroid orbit a deflection is indeed indicated, the GT would "hover" above the surface of the asteroid in the direction of the required acceleration vector for a duration adequate to achieve the desired velocity change. The orbit of the asteroid is continuously monitored throughout the deflection process and the end state is known in real time. The performance envelope for the GT includes most NEOs which experience close gravitational encounters prior to impact and those below 150-200 meters in diameter on a direct Earth impact trajectory.
Solar System constraints to nonminimally coupled gravity
Orfeu Bertolami; Riccardo March; Jorge Páramos
2013-06-05T23:59:59.000Z
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.
High Impact Technologies Forum: Harnessing American Ingenuity...
Office of Environmental Management (EM)
Forum: Harnessing American Ingenuity and Innovation to Catalyze Building Efficiency High Impact Technologies Forum: Harnessing American Ingenuity and Innovation to...
The early American motion picture industry: promoting American cultural hegemony
Wier, Theresa Joanne
1994-01-01T23:59:59.000Z
THE EARLY AMERICAN MOTION PICTURE INDUSTRY: PROMOTING AMERICAN CULTURAL HEGEMONY A thesis by THERESA JOANNE WIER Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTERS OF SCIENCE May 1994 Major Subject: Geography THE EARLY AMERICAN MOTION PICTURE INDUSTRY: PROMOTING AMERICAN CULTURAL HEGEMONY A Thesis by THERESA JOANNE WIER Submitted to the Texas AI(rM University in partial fulfillment...
56 SCIENTIFIC AMERICAN APRIL 2006 COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC.
Robins, Gabriel
56 SCIENTIFIC AMERICAN APRIL 2006 COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC. #12;www.sciam.com SCIENTIFIC AMERICAN 57 Computing with Quantum Knots uantum computers promise to perform calculations be- lieved to be impossible for ordinary computers. Some of those calculations are of great real-world
American Association of Petroleum Geologists
Kaufman, Alan Jay
American Association of Petroleum Geologists 40th Eastern Section Meeting September 24-29, 2011 MEETING SPONSORS #12;2011 Eastern Section American Association of Petroleum Geologists 40th Annual Meeting
of October 2002 African Americans
Kammen, Daniel M.
the impact of air pollution from coal-fired power plants upon the African American community. The Black
Gravity-Induced Vacuum Dominance
Lima, William C. C.; Vanzella, Daniel A. T. [Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 369, CEP 15980-900, Sao Carlos, SP (Brazil)
2010-04-23T23:59:59.000Z
It has been widely believed that, except in very extreme situations, the influence of gravity on quantum fields should amount to just small, subdominant contributions. This view seemed to be endorsed by the seminal results obtained over the last decades in the context of renormalization of quantum fields in curved spacetimes. Here, however, we argue that this belief is false by showing that there exist well-behaved spacetime evolutions where the vacuum energy density of free quantum fields is forced, by the very same background spacetime, to become dominant over any classical energy-density component. By estimating the time scale for the vacuum energy density to become dominant, and therefore for backreaction on the background spacetime to become important, we argue that this (infrared) vacuum dominance may bear unexpected astrophysical and cosmological implications.
Tom Fleming; Mark Gross; Ray Renken
1994-01-04T23:59:59.000Z
We define a simplified version of Regge quantum gravity where the link lengths can take on only two possible values, both always compatible with the triangle inequalities. This is therefore equivalent to a model of Ising spins living on the links of a regular lattice with somewhat complicated, yet local interactions. The measure corresponds to the natural sum over all 2^links configurations, and numerical simulations can be efficiently implemented by means of look-up tables. In three dimensions we find a peak in the ``curvature susceptibility'' which grows with increasing system size. However, the value of the corresponding critical exponent as well as the behavior of the curvature at the transition differ from that found by Hamber and Williams for the Regge theory with continuously varying link lengths.
Emergent Horava gravity in graphene
G. E. Volovik; M. A. Zubkov
2013-07-07T23:59:59.000Z
First of all, we reconsider the tight - binding model of monolayer graphene, in which the variations of the hopping parameters are allowed. We demonstrate that the emergent 2D Weitzenbock geometry as well as the emergent U(1) gauge field appear. The emergent gauge field is equal to the linear combination of the components of the zweibein. Therefore, we actually deal with the gauge fixed version of the emergent 2+1 D teleparallel gravity. In particular, we work out the case, when the variations of the hopping parameters are due to the elastic deformations, and relate the elastic deformations with the emergent zweibein. Next, we investigate the tight - binding model with the varying intralayer hopping parameters for the multilayer graphene with the ABC stacking. In this case the emergent 2D Weitzenbock geometry and the emergent U(1) gauge field appear as well, the emergent low energy effective field theory has the anisotropic scaling.
Dimensional Reduction in Quantum Gravity
G. 't Hooft
2009-03-20T23:59:59.000Z
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.
Central American electrical interconnection
Not Available
1988-12-01T23:59:59.000Z
A technical cooperation grant of $2.25 million, designed to strengthen the capacity of Central American countries to operate their regional interconnected electrical system, was announced by the Inter-American Development Bank (IDB). The grant, extended from the banks Fund for Special Operations, will help improve the capacity of the regions electric power companies to achieve economical, safe operation of the interconnected electric power systems. The funds will also be used to finance regional studies of the accords, procedures, regulations, and supervisory mechanisms for the system, as well as program development and data bases.
Loop Quantum Gravity 1. Classical framework : Ashtekar-Barbero connection
Sart, Remi
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) Â· it has to be modified
Ning Wu
2012-07-11T23:59:59.000Z
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.
Surface gravities for non-Killing horizons
Cropp, Bethan; Visser, Matt
2013-01-01T23:59:59.000Z
There are many logically and computationally distinct characterizations of the surface gravity of a horizon, just as there are many logically rather distinct notions of horizon. Fortunately, in standard general relativity, for stationary horizons, most of these characterizations are degenerate. However, in modified gravity, or in analogue spacetimes, horizons may be non-Killing or even non-null, and hence these degeneracies can be lifted. We present a brief overview of the key issues, specifically focusing on horizons in analogue spacetimes and universal horizons in modified gravity.
Status of Horava gravity: A personal perspective
Visser, Matt
2011-01-01T23:59:59.000Z
Horava gravity is a relatively recent (Jan 2009) idea in theoretical physics for trying to develop a quantum field theory of gravity. It is not a string theory, nor loop quantum gravity, but is instead a traditional quantum field theory that breaks Lorentz invariance at ultra-high (presumably trans-Planckian) energies, while retaining approximate Lorentz invariance at low and medium (sub-Planckian) energies. The challenge is to keep the Lorentz symmetry breaking controlled and small - small enough to be compatible with experiment. I will give a very general overview of what is going on in this field, paying particular attention to the disturbing role of the scalar graviton.
Oblique reflections of internal gravity wave beams
Karimi, Hussain H. (Hussain Habibullah)
2012-01-01T23:59:59.000Z
We study nonlinear effects in reflections of internal gravity wave beams in a continuously stratified liquid which are incident upon a uniform slope at an oblique angle. Wave motion in a stratified fluid medium is unique ...
Primordial Density Fluctuations in Phase Coupling Gravity
C. E. M. Batista; M. Schiffer
1996-01-10T23:59:59.000Z
In this paper we study the evolution of density perturbations in the framework of Phase Coupling Gravity theory at the very early universe. We show that these perturbation display an exponential-like behaviour.
Gravity waves from vortex dipoles and jets
Wang, Shuguang
2009-05-15T23:59:59.000Z
The dissertation first investigates gravity wave generation and propagation from jets within idealized vortex dipoles using a nonhydrostatic mesoscale model. Several initially balanced and localized jets induced by vortex dipoles are examined here...
A new vacuum for Loop Quantum Gravity
Bianca Dittrich; Marc Geiller
2015-05-05T23:59:59.000Z
We construct a new vacuum for loop quantum gravity, which is dual to the Ashtekar-Lewandowski vacuum. Because it is based on BF theory, this new vacuum is physical for $(2+1)$-dimensional gravity, and much closer to the spirit of spin foam quantization in general. To construct this new vacuum and the associated representation of quantum observables, we introduce a modified holonomy-flux algebra which is cylindrically consistent with respect to the notion of refinement by time evolution suggested in [1]. This supports the proposal for a construction of a physical vacuum made in [1,2], also for $(3+1)$-dimensional gravity. We expect that the vacuum introduced here will facilitate the extraction of large scale physics and cosmological predictions from loop quantum gravity.
Bounds on quantum communication via Newtonian gravity
D. Kafri; G. J. Milburn; J. M. Taylor
2014-10-08T23:59:59.000Z
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.
State sum models for quantum gravity
John W. Barrett
2000-10-12T23:59:59.000Z
This paper reviews the construction of quantum field theory on a 4-dimensional spacetime by combinatorial methods, and discusses the recent developments in the direction of a combinatorial construction of quantum gravity.
Energy conditions in f(R) gravity
Santos, J. [Universidade Federal do Rio Grande do Norte, Departamento de Fisica C.P. 1641, 59072-970 Natal-Rio Grande do Norte (Brazil); Departamento de Astronomia, Observatorio Nacional, 20921-400 Rio de Janeiro-Rio de Janeiro (Brazil); Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro-Rio de Janeiro (Brazil); Alcaniz, J. S.; Carvalho, F. C. [Departamento de Astronomia, Observatorio Nacional, 20921-400 Rio de Janeiro-Rio de Janeiro (Brazil); Reboucas, M. J. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro-Rio de Janeiro (Brazil)
2007-10-15T23:59:59.000Z
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 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.
Cosmology of modified (but second order) gravity
Tomi S. Koivisto
2009-10-21T23:59:59.000Z
This is a brief review of modified gravity cosmologies. Generically extensions of gravity action involve higher derivative terms, which can result in ghosts and instabilities. There are three ways to circumvent this: Chern-Simons terms, first order variational principle and nonlocality. We consider recent cosmological applications of these three classes of modified gravity models, in particular to the dark energy problem. The viable parameter spaces can be very efficiently constrained by taking into account cosmological data from all epochs in addition to Solar system tests and stability considerations. We make some new remarks concerning so called algebraic scalar-tensor theories, biscalar reformulation of nonlocal actions involving the inverse d'Alembertian, and a possible covariant formulation holographic cosmology with nonperturbative gravity.
Energy conditions in f(R)-gravity
J. Santos; J. S. Alcaniz; M. J. Reboucas; F. C. Carvalho
2007-09-06T23:59:59.000Z
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.
Test particle motion in modified gravity theories
Mahmood Roshan
2013-02-05T23:59:59.000Z
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. $\
Anisotropic induced gravity and inflationary universe
W. F. Kao
2006-12-09T23:59:59.000Z
Existence and stability analysis of the Kantowski-Sachs type universe in a higher derivative induced gravity theory is studied in details. Existence of one stable mode and one unstable mode is shown to be in favor of the inflationary universe. As a result, the de Sitter background can be made to be stable against anisotropic perturbations with proper constraints imposed on the coupling constants of the induced gravity model.
Gravity waves from cosmic bubble collisions
Salem, Michael P.; Saraswat, Prashant; Shaghoulian, Edgar, E-mail: mpsalem@stanford.edu, E-mail: ps88@stanford.edu, E-mail: edgars@stanford.edu [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, Stanford, California 94305 (United States)
2013-02-01T23:59:59.000Z
Our local Hubble volume might be contained within a bubble that nucleated in a false vacuum with only two large spatial dimensions. We study bubble collisions in this scenario and find that they generate gravity waves, which are made possible in this context by the reduced symmetry of the global geometry. These gravity waves would produce B-mode polarization in the cosmic microwave background, which could in principle dominate over the inflationary background.
The shape dynamics description of gravity
Tim Koslowski
2015-01-13T23:59:59.000Z
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.
Gravity as Quantum Foam In-Flow
Reginald T Cahill
2003-07-01T23:59:59.000Z
The new information-theoretic Process Physics provides an explanation of space as a quantum foam system in which gravity is an inhomogeneous flow of the quantum foam into matter. The older Newtonian and General Relativity theories for gravity are analysed. It is shown that Newtonian gravity may be written in the form of an in-flow. General Relativity is also analysed as an in-flow, for those cases where it has been tested. An analysis of various experimental data demonstrates that absolute motion relative to space has been observed by Michelson and Morley, Miller, Illingworth, Jaseja et al, Torr and Kolen, and by DeWitte. The Dayton Miller and Roland DeWitte data also reveal the in-flow of space into matter which manifests as gravity. The experimental data suggests that the in-flow is turbulent, which amounts to the observation of a gravitational wave phenomena. A new in-flow theory of gravity is proposed which passes all the tests that General Relativity was claimed to have passed, but as well the new theory suggests that the so-called spiral galaxy rotation-velocity anomaly may be explained without the need of `dark matter'. Various other gravitational anomalies also appear to be explainable. Newtonian gravity appears to be strictly valid only outside of spherically symmetric matter systems.
Encoding field theories into gravities
Aoki, Sinya; Onogi, Tetsuya
2015-01-01T23:59:59.000Z
We propose a method, which encodes the information of a $d$ dimensional quantum field theory into a $d+1$ dimensional gravity in the $1/N$ expansion. We first construct a $d+1$ dimensional field theory from the $d$ dimensional one via the gradient flow equation, whose flow time $t$ represents the energy scale of the system such that $t\\rightarrow 0$ corresponds to the ultra-violet (UV) while $t\\rightarrow\\infty$ to the infra-red (IR). We then define the induced metric from $d+1$ dimensional field operators. We show that the metric defined in this way becomes classical in the large $N$ limit, in a sense that quantum fluctuations of the metric are suppressed as $1/N$ due to the large $N$ factorization property. As a concrete example, we apply our method to the O(N) non-linear $\\sigma$ model in two dimensions. We calculate the induced metric in three dimensions, which is shown to describe De Sitter (dS) or Anti De Sitter (AdS) space in the massless limit, where the mass is dynamically generated in the O(N) non-l...
Universality of Gravity from Entanglement
Brian Swingle; Mark Van Raamsdonk
2014-05-12T23:59:59.000Z
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).
Bimetric gravity and dark matter
Laura Bernard; Luc Blanchet; Lavinia Heisenberg
2015-07-10T23:59:59.000Z
We review some recent proposals for relativistic models of dark matter in the context of bimetric gravity. The aim is to solve the problems of cold dark matter (CDM) at galactic scales, and to reproduce the phenomenology of the modified Newtonian dynamics (MOND), while still being in agreement with the standard cosmological model $\\Lambda$-CDM at large scales. In this context a promising alternative is dipolar dark matter (DDM) in which two different species of dark matter particles are separately coupled to the two metrics of bigravity and are linked together by an internal vector field. The phenomenology of MOND then results from a mechanism of gravitational polarization. Probably the best formulation of the model is within the framework of recently developed massive bigravity theories. Then the gravitational sector of the model is safe by construction, but a ghostly degree of freedom in the decoupling limit is still present in the dark matter sector. Future work should analyse the cosmological solutions of the model and check the post-Newtonian parameters in the solar system.
Quantum gravity and inventory accumulation
Scott Sheffield
2011-08-10T23:59:59.000Z
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.
Measuring antimatter gravity with muonium
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Kaplan, Daniel M.; Kirch, Klaus; Mancini, Derrick; Phillips, James D.; Phillips, Thomas J.; Roberts, Thomas J.; Terry, Jeff; Bravina, L.; Foka, Y.; Kabana, S.
2015-05-29T23:59:59.000Z
The gravitational acceleration of antimatter, ¯g, has never been directly measured and could bear importantly on our understanding of gravity, the possible existence of a fifth force, and the nature and early history of the universe. Only two avenues for such a measurement appear to be feasible: antihydrogen and muonium. The muonium measurement requires a novel, monoenergetic, low-velocity, horizontal muonium beam directed at an atom interferometer. The precision three-grating interferometer can be produced in silicon nitride or ultrananocrystalline diamond using state-of-the-art nanofabrication. The required precision alignment and calibration at the picometer level also appear to be feasible. With 100 nmmore »grating pitch, a 10% measurement of ¯g can be made using some months of surface-muon beam time, and a 1% or better measurement with a correspondingly larger exposure. This could constitute the first gravitational measurement of leptonic matter, of 2nd-generation matter and, possibly, the first measurement of the gravitational acceleration of antimatter.« less
A Kinetic Theory Approach to Quantum Gravity
B. L. Hu
2002-04-22T23:59:59.000Z
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).
Review on the quantization of gravity
Benjamin Schulz
2014-09-29T23:59:59.000Z
This is a review article on quantum gravity. In section 1, the Penrose singularity theorem is proven. In section 2, the covariant quantization approach of gravity is reviewed. In section 3, an article by Hawking is reviewed that shows the gravitational path integral at one loop level to be dominated by contributions from some kind of virtual gravitational instantons. In section 4, the canonical, non-perturbative quantization approach is reviewed. In section 5, arguments from Hawking are mentioned which show the gravitational path integral to be an approximate solution of the Wheeler deWitt equation. In section 6, the black hole entropy is derived in various ways. Section 6.1 uses the gravitational path integral for this calculation. Section 6.2 shows how the black hole entropy can be derived from canonical quantum gravity. In section 7.1, arguments from Dvali and Gomez who claim that gravity can be quantized in a way which would be in some sense self-complete are critically assessed. In section 7.2 a model from Dvali and Gomez for the description of quantum mechanical black holes is critically assessed and compared with the standard quantization methods of gravity.
Gravity as Quantum Foam In-Flow
Cahill, R T
2003-01-01T23:59:59.000Z
The new information-theoretic Process Physics provides an explanation of space as a quantum foam system in which gravity is an inhomogeneous flow of the quantum foam into matter. The older Newtonian and General Relativity theories for gravity are analysed. It is shown that Newtonian gravity may be written in the form of an in-flow. General Relativity is also analysed as an in-flow, for those cases where it has been tested. An analysis of various experimental data demonstrates that absolute motion relative to space has been observed by Michelson and Morley, Miller, Illingworth, Jaseja et al, Torr and Kolen, and by DeWitte. The Dayton Miller and Roland DeWitte data also reveal the in-flow of space into matter which manifests as gravity. The experimental data suggests that the in-flow is turbulent, which amounts to the observation of a gravitational wave phenomena. A new in-flow theory of gravity is proposed which passes all the tests that General Relativity was claimed to have passed, but as well the new theory...
New American Home 2009 (Brochure)
Not Available
2008-12-01T23:59:59.000Z
This brochure details the New American Home 2009, which demonstrates the use of innovative building materials, cutting-edge design, and the latest construction techniques.
Opportunities and Inaudibilities: Asian American Internet Musicians
Regullano, Eileen
2015-01-01T23:59:59.000Z
60–73. Spooner, Tom. “Asian-Americans and the Internet. ”Pew Research Center’s Internet & American Life Project.americans-and-the-internet/. Timothy DeLaGhetto Dog Joke. ,
Gravity tests and the Pioneer anomaly
Marc-Thierry Jaekel; Serge Reynaud
2005-11-04T23:59:59.000Z
Experimental tests of gravity performed in the solar system show a good agreement with general relativity. The latter is however challenged by the Pioneer anomaly which might be pointing at some modification of gravity law at ranges of the order of the size of the solar system. We introduce a metric extension of general relativity which, while preserving the equivalence principle, modifies the coupling between curvature and stress tensors and, therefore, the metric solution in the solar system. The ``post-Einsteinian extension'' replaces Newton gravitation constant by two running coupling constants, which depend on the scale and differ in the sectors of traceless and traced tensors, so that the metric solution is characterized by two gravitation potentials. The extended theory has the capability to preserve compatibility with gravity tests while accounting for the Pioneer anomaly. It can also be tested by new experiments or, maybe, by having a new look at data of already performed experiments.
Solar System Constraints on Disformal Gravity Theories
Hiu Yan Ip; Jeremy Sakstein; Fabian Schmidt
2015-07-02T23:59:59.000Z
Disformal theories of gravity are scalar-tensor theories where the scalar couples derivatively to matter via the Jordan frame metric. These models have recently attracted interest in the cosmological context since they admit accelerating solutions. We derive the solution for a static isolated mass in generic disformal gravity theories and transform it into the parameterised post-Newtonian form. This allows us to investigate constraints placed on such theories by local tests of gravity. The tightest constraints come from preferred-frame effects due to the motion of the Solar System with respect to the evolving cosmological background field. The constraints we obtain improve upon the previous solar system constraints by two orders of magnitude, and constrain the scale of the disformal coupling for generic models to $\\mathcal{M} \\gtrsim 100$ eV. These constraints render all disformal effects irrelevant for cosmology.
Detailed balance in Horava-Lifshitz gravity
Gianluca Calcagni
2010-02-04T23:59:59.000Z
We study Horava-Lifshitz gravity in the presence of a scalar field. When the detailed balance condition is implemented, a new term in the gravitational sector is added in order to maintain ultraviolet stability. The four-dimensional theory is of a scalar-tensor type with a positive cosmological constant and gravity is nonminimally coupled with the scalar and its gradient terms. The scalar field has a double-well potential and, if required to play the role of the inflation, can produce a scale-invariant spectrum. The total action is rather complicated and there is no analog of the Einstein frame where Lorentz invariance is recovered in the infrared. For these reasons it may be necessary to abandon detailed balance. We comment on open problems and future directions in anisotropic critical models of gravity.
Entropic force, noncommutative gravity, and ungravity
Nicolini, Piero [Frankfurt Institute for Advanced Studies (FIAS), Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany)
2010-08-15T23:59:59.000Z
After recalling the basic concepts of gravity as an emergent phenomenon, we analyze the recent derivation of Newton's law in terms of entropic force proposed by Verlinde. By reviewing some points of the procedure, we extend it to the case of a generic quantum gravity entropic correction to get compelling deviations to the Newton's law. More specifically, we study: (1) noncommutative geometry deviations and (2) ungraviton corrections. As a special result in the noncommutative case, we find that the noncommutative character of the manifold would be equivalent to the temperature of a thermodynamic system. Therefore, in analogy to the zero temperature configuration, the description of spacetime in terms of a differential manifold could be obtained only asymptotically. Finally, we extend the Verlinde's derivation to a general case, which includes all possible effects, noncommutativity, ungravity, asymptotically safe gravity, electrostatic energy, and extra dimensions, showing that the procedure is solid versus such modifications.
Solar System Constraints on Disformal Gravity Theories
Ip, Hiu Yan; Schmidt, Fabian
2015-01-01T23:59:59.000Z
Disformal theories of gravity are scalar-tensor theories where the scalar couples derivatively to matter via the Jordan frame metric. These models have recently attracted interest in the cosmological context since they admit accelerating solutions. We derive the solution for a static isolated mass in generic disformal gravity theories and transform it into the parameterised post-Newtonian form. This allows us to investigate constraints placed on such theories by local tests of gravity. The tightest constraints come from preferred-frame effects due to the motion of the Solar System with respect to the evolving cosmological background field. The constraints we obtain improve upon the previous solar system constraints by two orders of magnitude, and constrain the scale of the disformal coupling for generic models to $\\mathcal{M} \\gtrsim 100$ eV. These constraints render all disformal effects irrelevant for cosmology.
Emergence in Holographic Scenarios for Gravity
Dieks, Dennis; de Haro, Sebastian
2015-01-01T23:59:59.000Z
'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 ...
Quantum gravity effects in the Kerr spacetime
Reuter, M. [Institute of Physics, University of Mainz, Staudingerweg 7, D-55099 Mainz (Germany); Tuiran, E. [Departamento de Fisica, Universidad del Norte, Km 5 via a Puerto Colombia, AA-1569 Barranquilla (Colombia)
2011-02-15T23:59:59.000Z
We analyze the impact of the leading quantum gravity effects on the properties of black holes with nonzero angular momentum by performing a suitable renormalization group improvement of the classical Kerr metric within quantum Einstein gravity. In particular, we explore the structure of the horizons, the ergosphere, and the static limit surfaces as well as the phase space available for the Penrose process. The positivity properties of the effective vacuum energy-momentum tensor are also discussed and the 'dressing' of the black hole's mass and angular momentum are investigated by computing the corresponding Komar integrals. The pertinent Smarr formula turns out to retain its classical form. As for their thermodynamical properties, a modified first law of black-hole thermodynamics is found to be satisfied by the improved black holes (to second order in the angular momentum); the corresponding Bekenstein-Hawking temperature is not proportional to the surface gravity.
Weatherization Formula Grants - American Recovery and Reinvestment...
Weatherization Formula Grants - American Recovery and Reinvestment Act (ARRA) Weatherization Formula Grants - American Recovery and Reinvestment Act (ARRA) U.S. Department of...
Comments of North American Electric Reliability Corporation ...
North American Electric Reliability Corporation (NERC) to DOE Smart Grid RFI: Addressing Policy and Logistical Challenges Comments of North American Electric Reliability...
American Gas Association | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
American Gas Association American Gas Association Memorandum Summarizing Ex Parte Communication 111011ExParte.pdf More Documents & Publications Ex Parte Memorandum - Natural...
Native American Finance Officers Association Conference | Department...
Office of Environmental Management (EM)
Native American Finance Officers Association Conference Native American Finance Officers Association Conference March 5, 2012 - 5:50pm Addthis This event will take place on March...
NORTH AMERICAN ELECTRIC RELIABILITY COUNCIL: Preliminary Disturbance...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Report More Documents & Publications North American Electric Reliability Council Power Outage Update North American Electric Reliability Council Outage Announcement Electric System...
Energy Innovation: Green Button Initiative Empowering Americans...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Innovation: Green Button Initiative Empowering Americans to Save Energy and Money Energy Innovation: Green Button Initiative Empowering Americans to Save Energy and Money February...
Stratospheric gravity wave simulation over Greenland during 24 January 2005
Limpasuvan, Varavut
gravity waves because of imbalance of the jet stream. Where the horizontal jet is rapidly changing speed anticyclonic jet stream over the North Atlantic. Likewise, inertia gravity waves can result from synoptic
Ground Gravity Survey At Baltazor Hot Springs Area (Isherwood...
gravity low within the valley area that presumably is related to low-density Cenozoic sediments. The steep gravity gradient along the east side of the valley suggests a...
Theoretical and experimental study of nonlinear internal gravity wave beams
Tabaei Befrouei, Ali, 1974-
2005-01-01T23:59:59.000Z
Continuously stratified fluids, like the atmosphere and the oceans, support internal gravity waves due to the effect of buoyancy. This type of wave motion is anisotropic since gravity provides a preferred direction. As a ...
Gravity modeling of Cenozoic extensional basins, offshore Vietnam
Mauri, Steven Joseph
1993-01-01T23:59:59.000Z
Integrating Bouguer gravity and satellite-derived free-air gravity data with published geological and geophysical data allows modeling crustal structure and estimating crustal extension for the hydrocarbon bearing Mekong ...
The inverse-square law and quantum gravity
Nieto, M.M.; Goldman, T.; Hughes, R.J.
1988-01-01T23:59:59.000Z
This paper briefly discusses a modification to central potential of gravity when antimatter is involved and the possible existence of quantum gravity and a fifth force of nature. 1 ref. (LSP)
Gravity Data for west-central Colorado
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Zehner, Richard
West -108.366692 East -105.478847 North 40.932361 South 36.961606 Data from From University of Texas: Pan American Center for Earth and Environmental Studies
Prima Facie Questions in Quantum Gravity
C. J. Isham
1993-10-22T23:59:59.000Z
The long history of the study of quantum gravity has thrown up a complex web of ideas and approaches. The aim of this article is to unravel this web a little by analysing some of the {\\em prima facie\\/} questions that can be asked of almost any approach to quantum gravity and whose answers assist in classifying the different schemes. Particular emphasis is placed on (i) the role of background conceptual and technical structure; (ii) the role of spacetime diffeomorphisms; and (iii) the problem of time.
Linear Stability Analysis of Dynamical Quadratic Gravity
Dimitry Ayzenberg; Kent Yagi; Nicolas Yunes
2014-03-18T23:59:59.000Z
We perform a linear stability analysis of dynamical, quadratic gravity in the high-frequency, geometric optics approximation. This analysis is based on a study of gravitational and scalar modes propagating on spherically-symmetric and axially-symmetric, vacuum solutions of the theory. We find dispersion relations that do no lead to exponential growth of the propagating modes, suggesting the theory is linearly stable on these backgrounds. The modes are found to propagate at subluminal and superluminal speeds, depending on the propagating modes' direction relative to the background geometry, just as in dynamical Chern-Simons gravity.
Nonlocal Gravity in the Solar System
Chicone, C
2015-01-01T23:59:59.000Z
The implications of the recent classical nonlocal generalization of Einstein's theory of gravitation for gravitational physics in the Solar System are investigated. In this theory, the nonlocal character of gravity simulates dark matter. Nonlocal gravity in the Newtonian regime involves a reciprocal kernel with three spatial parameters, of which two have already been determined from the rotation curves of spiral galaxies and the internal dynamics of clusters of galaxies. However, the short-range parameter a_0 remains to be determined. In this connection, the nonlocal contribution to the perihelion precession of a planetary orbit is estimated and a preliminary lower limit on a_0 is determined.
Holographic superconductors from the massive gravity
Hua Bi Zeng; Jian-Pin Wu
2014-09-24T23:59:59.000Z
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.
Weak Gravity Conjecture for Noncommutative Field Theory
Qing-Guo Huang; Jian-Huang She
2006-11-20T23:59:59.000Z
We investigate the weak gravity bounds on the U(1) gauge theory and scalar field theories in various dimensional noncommutative space. Many results are obtained, such as the upper bound on the noncommutative scale $g_{YM}M_p$ for four dimensional noncommutative U(1) gauge theory. We also discuss the weak gravity bounds on their commutative counterparts. For example, our result on 4 dimensional noncommutative U(1) gauge theory reduces in certain limit to its commutative counterpart suggested by Arkani-Hamed et.al at least at tree-level.
Energy Distribution in f(R) Gravity
M. Sharif; M. Farasat Shamir
2009-12-18T23:59:59.000Z
The well-known energy problem is discussed in f(R) theory of gravity. We use the generalized Landau-Lifshitz energy-momentum complex in the framework of metric f(R) gravity to evaluate the energy density of plane symmetric solutions for some general f(R) models. In particular, this quantity is found for some popular choices of f(R) models. The constant scalar curvature condition and the stability condition for these models are also discussed. Further, we investigate the energy distribution of cosmic string spacetime.
Violation of Energy Bounds in Designer Gravity
Thomas Hertog
2006-07-31T23:59:59.000Z
We continue our study of the stability of designer gravity theories, where one considers anti-de Sitter gravity coupled to certain tachyonic scalars with boundary conditions defined by a smooth function W. It has recently been argued there is a lower bound on the conserved energy in terms of the global minimum of W, if the scalar potential arises from a superpotential P and the scalar reaches an extremum of P at infinity. We show, however, there are superpotentials for which these bounds do not hold.
Multidimensional Gravity on the Principal Bundles
V. D. Dzhunushaliev
1997-11-10T23:59:59.000Z
The multidimensional gravity on the total space of principal bundle is considered. In this theory the gauge fields arise as nondiagonal components of multidimensional metric. The spherically symmetric and cosmology solutions for gravity on SU(2) principal bundle are obtained. The static spherically symmetric solution is wormhole-like solution located between two null surfaces, in contrast to 4D Einstein-Yang-Mills theory where corresponding solution (black hole) located outside of event horizon. Cosmology solution (at least locally) has the bouncing off effect for spatial dimensions. In spirit of Einstein these solutions are vacuum solutions without matter.
Hogg, Charlie A. R.; Dalziel, Stuart B.; Huppert, Herbert E.; Imberger, Jörg
2015-01-01T23:59:59.000Z
by noise in the conductivity measurements which was minimised by the median 10 Gravity currents filling basins: influence of Reynolds number on entrainment Source x z Outflow ? D zf A = D/(sin ? cos ?) FIG. 6: Schematic of the basin. The gravity current... in these experiments, the horizontal length at the top of the basin is A = D/(sin ? cos ?) . The virtual origin is the origin for a source of buoyancy alone that would give rise to the volume and buoyancy flux that occurs at the physical origin. 12 Gravity currents...
Hodgson, S.F.
1987-07-01T23:59:59.000Z
The Central American Energy Resources Project is designed to help the countries of Honduras, Costa Rica, El Salvador, Guatemala, and Panama develop their geothermal resources. Auxiliary project goals are to increase economic development and employment in Central America; to provide a scientific basis for the private sector to develop natural resources; and to provide scientific training to in-country scientists, engineers, and technicians. The energy resources project began in March 1985. The progress being made in El Salvador (production well logging and geophysical operations), Panama (site selection for the first temperature-gradient well), and Honduras (well drilling of temperature-gradient wells) is summarized.
Central American resource studies
Van Eeckhout, E.; Laughlin, A.W.
1989-01-01T23:59:59.000Z
Los Alamos National Laboratory has been working with five Central American countries to assist in the development of their energy and mineral resources. Since 1985, mineral resources in Costa Rica, peat resources in Costa Rica and Panama, geothermal energy resources in Honduras and Guatemala, and geothermal field development in El Salvador and Costa Rica have been topics of study. This paper presents an overview of this work -- within these proceedings are papers that deal with specific aspects of each topic, and these will be duly noted. 15 refs., 4 figs.
American Physical Society Fellows
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), 2002; Level:5 TablesExports(Journal Article) |govInstrumentsmfrirt DocumentationSitesWeather Outreach HomeDeKalb CountyAlumni Alumni PARC/I-CARESX-ray,NuclearAmerican
Broader source: Energy.gov (indexed) [DOE]
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), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23Tribal Energy Program GrantState Energy Loan Program The2012 |Reduces CarbonSamAudit ReportAmerican
AMERICAN STATISTICAL ASSOCIATION (ASA)
U.S. Energy Information Administration (EIA) Indexed Site
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 onsource History View NewUS National FuelYancey County, NorthDiesel3, 2013TWOEnergy Supply Crude17.August3AMERICAN
Nordstrom's scalar theory of gravity and the equivalence principle
Nathalie Deruelle
2011-04-24T23:59:59.000Z
Nordstrom's theory of gravity, which describes gravity by a scalar field in flat spacetime, is observationally ruled out. It is however the only theory of gravity with General Relativity to obey the strong equivalence principle. I show in this paper that this remarkable property is true beyond post-newtonian level and can be related to the existence of a 'Nordstrom-Katz' superpotential.
Gravity Wave Lensing Ryan Elandt, Mostafa Shakeri & Reza Alam
Alam, Mohammad-Reza
Gravity Wave Lensing Ryan Elandt, Mostafa Shakeri & Reza Alam Department of Mechanical Engineering waves caused by small seabed features (the so called Bragg resonance) can be utilized to create equivalent of lenses and curved mirrors for surface gravity waves. Such gravity wave lenses, which are merely
The Mars Gravity Biosatellite as an innovative partial gravity research platform
Fulford-Jones, Thaddeus R. F
2008-01-01T23:59:59.000Z
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 ...
Webb, Spahr C.
, Petrologic and Seismic Expedition (GLIMPSE) study area from seismic refraction data R. Chadwick Holmes,1, Intraplate Melting, Petrologic and Seismic Expedition (GLIMPSE) experiment investigated the velocity in the Gravity Lineations, Intraplate Melting, Petrologic and Seismic Expedition (GLIMPSE) study area from
Topological Black Holes in Quantum Gravity
J. Kowalski-Glikman; D. Nowak-Szczepaniak
2000-07-31T23:59:59.000Z
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.
Energy definition for quadratic curvature gravities
Ahmet Baykal
2012-12-03T23:59:59.000Z
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.
Running Coupling Constants in 2D Gravity
Christof Schmidhuber
1993-08-26T23:59:59.000Z
The renormalization group flow in two--dimensional field theories that are coupled to gravity is discussed at the example of the sine-Gordon model. In order to derive the phase diagram in agreement with the matrix model results, it is necessary to generalize the theory of David, Distler and Kawai.
Second order noncommutative corrections to gravity
Calmet, Xavier [Universite Libre de Bruxelles, Service de Physique Theorique, CP225 Boulevard du Triomphe (Campus plaine), B-1050 Brussels (Belgium); Kobakhidze, Archil [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 (United States)
2006-08-15T23:59:59.000Z
In this work, we calculate the leading order corrections to general relativity formulated on a canonical noncommutative spacetime. These corrections appear in the second order of the expansion in theta. First order corrections can only appear in the gravity-matter interactions. Some implications are briefly discussed.
Ultrasonic hydrometer. [Specific gravity of electrolyte
Swoboda, C.A.
1982-03-09T23:59:59.000Z
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.
The diffeomorphism algebra approach to quantum gravity
T. A. Larsson
1999-09-13T23:59:59.000Z
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.
p-wave superconductors in dilaton gravity
ZhongYing Fan
2013-10-08T23:59:59.000Z
In this paper, we study peculiar properties of p-wave superconductors in dilaton gravity. The scale invariance of the bulk geometry is effectively broken due to the existence of dilaton. By coupling the dilaton to the non-Abelian gauge field, i.e., $-\\frac14 e^{-\\beta \\Phi} F^a_{\\mu\
Topology in 4D simplicial quantum gravity
S. Bilke; Z. Burda; B. Petersson
1996-11-22T23:59:59.000Z
We simulate 4d simplicial gravity for three topologis S4, S3xS1, (S1)^4 and show that the free energy for these three fixed topology ensembles is the same in the thermodynamic limit. We show, that the next-to-leading order corrections, at least away from the critical point, can be described by kinematic sources.
Measuring the Earth's gravity field with cold atom interferometers
Carraz, Olivier; Massotti, Luca; Haagmans, Roger; Silvestrin, Pierluigi
2015-01-01T23:59:59.000Z
The scope of the paper is to propose different concepts for future space gravity missions using Cold Atom Interferometers (CAI) for measuring the diagonal elements of the gravity gradient tensor, the spacecraft angular velocity and the spacecraft acceleration. The aim is to achieve better performance than previous space gravity missions due to a very low white noise spectral behaviour of the CAI instrument and a very high common mode rejection, with the ultimate goals of determining the fine structures of the gravity field with higher accuracy than GOCE and detecting time-variable signals in the gravity field.
LGBT African-American Individuals and African-American Same-Sex Couples
Gates, Gary J.; Kastanis, Angel
2013-01-01T23:59:59.000Z
of African-American same-sex couples are raising children.African-American same-sex couples raising children reportAfrican- American different-sex couples ($47,300 vs. $
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Wind Power - Idaho Wind Anemometer Loan Program American FallsRockland Site 106 Latitude: N. 42 deg. 40.682' Longitude: W. 112 deg. 46.325' Elevation: 6579' Anemometer Height: 20...
Geothermal energy for American Samoa
Not Available
1980-03-01T23:59:59.000Z
The geothermal commercialization potential in American Samoa was investigated. With geothermal energy harnessed in American Samoa, a myriad of possibilities would arise. Existing residential and business consumers would benefit from reduced electricity costs. The tuna canneries, demanding about 76% of the island's process heat requirements, may be able to use process heat from a geothermal source. Potential new industries include health spas, aquaculture, wood products, large domestic and transhipment refrigerated warehouses, electric cars, ocean nodule processing, and a hydrogen economy. There are no territorial statutory laws of American Samoa claiming or reserving any special rights (including mineral rights) to the territorial government, or other interests adverse to a land owner, for subsurface content of real property. Technically, an investigation has revealed that American Samoa does possess a geological environment conducive to geothermal energy development. Further studies and test holes are warranted.
An analysis of residential window waterproofing systems
Parsons, Austin, 1959-
2004-01-01T23:59:59.000Z
The prevalence of vinyl nail-on windows in the North American new home construction market has prompted ASTM International to write ASTM E2112-01 "Standard Practice for Installation of Exterior Windows, Doors and Skylights". ...
Conceptual Aspects of Gauge/Gravity Duality
de Haro, Sebastian; Butterfield, Jeremy
2015-01-01T23:59:59.000Z
We give an introductory review of gauge/gravity duality, and associated ideas of holography, emphasising the conceptual aspects. The opening Sections gather the ingredients, viz. anti-de Sitter spacetime, conformal field theory and string theory, that we need for presenting, in Section 5, the central and original example: Maldacena's AdS/CFT correspondence. Sections 6 and 7 develop the ideas of this example, also in applications to condensed matter systems, QCD, and hydrodynamics. Sections 8 and 9 discuss the possible extensions of holographic ideas to de Sitter spacetime and to black holes. Section 10 discusses the bearing of gauge/gravity duality on two philosophical topics: the equivalence of physical theories, and the idea that spacetime, or some features of it, are emergent.
Hydrogen atom in Palatini theories of gravity
Gonzalo J. Olmo
2008-06-03T23:59:59.000Z
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.
Quantum Gravity models - brief conceptual summary
Jerzy Lukierski
2014-11-27T23:59:59.000Z
After short historical overview we describe the difficulties with application of standard QFT methods in quantum gravity (QG). The incompatibility of QG with the use of classical continuous space-time required conceptually new approach. We present briefly three proposals: loop quantum gravity (LQG), the field-theoretic framework on noncommutative space-time and QG models formulated on discretized (triangularized) space-time. We evaluate these models as realizing expected important properties of QG: background independence, consistent quantum diffeomorphisms, noncommutative or discrete structure of space-time at very short distances, finite/renormalizable QG corrections. We only briefly outline an important issue of embedding QG into larger geometric and dynamical frameworks (e.g. supergravity, (super)strings, p-branes, M-theory), with the aim to achieve full unification of all fundamental interactions.
Chaotic inflation in higher derivative gravity theories
Myrzakul, Shynaray; Sebastiani, Lorenzo
2015-01-01T23:59:59.000Z
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.
Infrared modification of gravity from conformal symmetry
Gegenberg, Jack; Seahra, Sanjeev S
2015-01-01T23:59:59.000Z
We reconsider a gauge theory of gravity in which the gauge group is the conformal group SO(4,2) and the action is of the Yang-Mills form, quadratic in the curvature. The resulting gravitational theory exhibits local conformal symmetry and reduces to Weyl-squared gravity under certain conditions. When the theory is linearized about flat spacetime, we find that matter which couples to the generators of special conformal transformations reproduces Newton's inverse square law. Conversely, matter which couples to generators of translations induces a constant and possibly repulsive force far from the source, which may be relevant for explaining the late time acceleration of the universe. The coupling constant of theory is dimensionless, which means that it is potentially renormalizable.
Charged Cylindrical Black Holes in Conformal Gravity
Jackson Levi Said; Joseph Sultana; Kristian Zarb Adami
2013-01-04T23:59:59.000Z
Considering cylindrical topology we present the static solution for a charged black hole in conformal gravity. We show that unlike the general relativistic case there are two different solutions, both including a factor that when set to zero recovers the familiar static charged black string solution in Einstein's theory. This factor gives rise to a linear term in the potential that also features in the neutral case and may have significant ramifications for particle trajectories.
Exact Gravity Dual of a Gapless Superconductor
George Koutsoumbas; Eleftherios Papantonopoulos; George Siopsis
2009-06-17T23:59:59.000Z
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.
Holographic Superconductivity with Gauss-Bonnet gravity
Ruth Gregory
2010-12-07T23:59:59.000Z
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.
Holographic Superconductors in Horava-Lifshitz Gravity
Kai Lin; Elcio Abdalla; Anzhong Wang
2014-06-18T23:59:59.000Z
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.
Gravity controlled anti-reverse rotation device
Dickinson, Robert J. (Shaler Township, Allegheny County, PA); Wetherill, Todd M. (Lower Burrell, PA)
1983-01-01T23:59:59.000Z
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.
QPOs: Einstein's gravity non-linear resonances
Paola Rebusco; Marek A. Abramowicz
2006-01-30T23:59:59.000Z
There is strong evidence that the observed kHz Quasi Periodic Oscillations (QPOs) in the X-ray flux of neutron star and black hole sources in LMXRBs are linked to Einstein's General Relativity. Abramowicz&Klu\\'zniak (2001) suggested a non-linear resonance model to explain the QPOs origin: here we summarize their idea and the development of a mathematical toy-model which begins to throw light on the nature of Einstein's gravity non-linear oscillations.
Gravity and Yang-Mills amplitude relations
Bjerrum-Bohr, N. E. J.; Damgaard, Poul H.; Soendergaard, Thomas [Niels Bohr International Academy and Discovery Center, Niels Bohr Institute, Blegdamsvej 17, DK-2100, Copenhagen O (Denmark); FengBo [Center of Mathematical Science, Zhejiang University, Hangzhou (China)
2010-11-15T23:59:59.000Z
Using only general features of the S matrix and quantum field theory, we prove by induction the Kawai-Lewellen-Tye relations that link products of gauge theory amplitudes to gravity amplitudes at tree level. As a bonus of our analysis, we provide a novel and more symmetric form of these relations. We also establish an infinite tower of new identities between amplitudes in gauge theories.
Equivalence principle in scalar-tensor gravity
Dirk Puetzfeld; Yuri N. Obukhov
2015-05-06T23:59:59.000Z
We present a direct confirmation of the validity of the equivalence principle for unstructured test bodies in scalar tensor gravity. Our analysis is complementary to previous approaches and valid for a large class of scalar-tensor theories of gravitation. A covariant approach is used to derive the equations of motion in a systematic way and allows for the experimental test of scalar-tensor theories by means of extended test bodies.
Twisted covariant noncommutative self-dual gravity
Estrada-Jimenez, S.; Garcia-Compean, H.; Obregon, O.; Ramirez, C. [Centro de Estudios en Fisica y Matematicas Basicas y Aplicadas, Universidad Autonoma de Chiapas, Calle 4 Oriente Norte 1428, Tuxtla Gutierrez, Chiapas (Mexico); Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del IPN, P.O. Box 14-740, 07000 Mexico D.F. (Mexico); Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Monterrey, PIIT, Via del Conocimiento 201, Autopista nueva al Aeropuerto km 9.5, 66600, Apodaca Nuevo Leon (Mexico); Instituto de Fisica de la Universidad de Guanajuato, P.O. Box E-143, 37150, Leon Gto. (Mexico); Facultad de Ciencias Fisico Matematicas, Universidad Autonoma de Puebla, P.O. Box 1364, 72000, Puebla (Mexico)
2008-12-15T23:59:59.000Z
A twisted covariant formulation of noncommutative self-dual gravity is presented. The formulation for constructing twisted noncommutative Yang-Mills theories is used. It is shown that the noncommutative torsion is solved at any order of the {theta} expansion in terms of the tetrad and some extra fields of the theory. In the process the first order expansion in {theta} for the Plebanski action is explicitly obtained.
Russell, Timothy Dale
2013-01-01T23:59:59.000Z
and the Spanish American War. ” Indiana Magazine of History,the Spanish American War, The Sixth Virginia Volunteers. ”African Americans and the War Against Spain. ” The North
McMahon, Jennifer M.
2011-01-01T23:59:59.000Z
Dead Stars: American and Philippine Literary Perspectives onthe American Colonization of the Philippines (Quezon City:University of the Philippines Press, 2011). Published with
Abelian-Higgs strings in Rastall gravity
Eugenio R. Bezerra de Mello; Julio C. Fabris; Betti Hartmann
2015-04-02T23:59:59.000Z
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.
Emergent gravity and ether-drift experiments
M. Consoli; L. Pappalardo
2010-05-04T23:59:59.000Z
According to several authors, gravity might be a long-wavelength phenomenon emerging in some 'hydrodynamic limit' from the same physical, flat-space vacuum viewed as a form of superfluid medium. In this framework, light might propagate in an effective acoustic geometry and exhibit a tiny anisotropy that could be measurable in the present ether-drift experiments. By accepting this view of the vacuum, one should also consider the possibility of sizeable random fluctuations of the signal that reflect the stochastic nature of the underlying `quantum ether' and could be erroneously interpreted as instrumental noise. To test the present interpretation, we have extracted the mean amplitude of the signal from various experiments with different systematics, operating both at room temperature and in the cryogenic regime. They all give the same consistent value = O (10^{-15}) which is precisely the magnitude expected in an emergent-gravity approach, for an apparatus placed on the Earth's surface. Since physical implications could be substantial, it would be important to obtain more direct checks from the instantaneous raw data and, possibly, with new experimental set-ups operating in gravity-free environments.
Cosmology with Coupled Gravity and Dark Energy
Ti-Pei Li
2015-01-13T23:59:59.000Z
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.
Quantum Gravito-Optics: A Light Route from Semiclassical Gravity to Quantum Gravity
Unnikrishnan, C S
2015-01-01T23:59:59.000Z
Quantum gravity remains an elusive theory, in spite of our thorough understanding of the quantum theory and the general theory of relativity separately, presumably due to the lack of any observational clues. We argue that the theory of quantum gravity has a strong constraining anchor in the sector of gravitational radiation ensuring reliable physical clues, albeit in a limited observable form. In particular, all types of gravitational waves expected to be observable in LIGO-like advanced detectors are fully quantum mechanical states of radiation. Exact equivalence of the full quantum gravity theory with the familiar semiclassical theory is ensured in the radiation sector, in most real situations where the relevant quantum operator functions are normal ordered, by the analogue of the optical equivalence theorem in quantum optics. We show that this is indeed the case for detection of the waves from a massive binary system, a single gravitational atom, that emits coherent radiation. The idea of quantum-gravitati...
Kristofer Davis, M. Andy Kass, and Yaoguo Li, Center for Gravity, Electrical and Magnetic Studies, Colorado
Cooling, Gravity and Geometry: Flow-driven Massive Core Formation
Fabian Heitsch; Lee Hartmann; Adrianne D. Slyz; Julien E. G. Devriendt; Andreas Burkert
2007-09-15T23:59:59.000Z
We study numerically the formation of molecular clouds in large-scale colliding flows including self-gravity. The models emphasize the competition between the effects of gravity on global and local scales in an isolated cloud. Global gravity builds up large-scale filaments, while local gravity -- triggered by a combination of strong thermal and dynamical instabilities -- causes cores to form. The dynamical instabilities give rise to a local focusing of the colliding flows, facilitating the rapid formation of massive protostellar cores of a few 100 M$_\\odot$. The forming clouds do not reach an equilibrium state, though the motions within the clouds appear comparable to ``virial''. The self-similar core mass distributions derived from models with and without self-gravity indicate that the core mass distribution is set very early on during the cloud formation process, predominantly by a combination of thermal and dynamical instabilities rather than by self-gravity.
Analysis of faults using gravity methods in Mason County, Texas
Milligan, Michael Glen
1992-01-01T23:59:59.000Z
Committee: Dr. D. A. Fahlquist Dr. B. Johnson The objective of this study is to determine the applicability of gravity profiling methods for determining the location and throw of a series of faults related to a structural graben in northern Mason County... profiles. For two faults with the best geologic control, the best-fit gravity models compared favorably with the the geologic model constructed by Randolph (1991) on the basis of surface mapping, structural control and well control. The gravity models...
Fab 5: noncanonical kinetic gravity, self tuning, and cosmic acceleration
Appleby, Stephen A.; Linder, Eric V. [Institute for the Early Universe WCU, Ewha Womans University, Seoul (Korea, Republic of); Felice, Antonio De, E-mail: stephen.appleby@ewha.ac.kr, E-mail: adefelic@gmail.com, E-mail: evlinder@lbl.gov [ThEP's CRL, NEP, The Institute for Fundamental Study, Naresuan University, Phitsanulok 65000 (Thailand)
2012-10-01T23:59:59.000Z
We investigate circumstances under which one can generalize Horndeski's most general scalar-tensor theory of gravity. Specifically we demonstrate that a nonlinear combination of purely kinetic gravity terms can give rise to an accelerating universe without the addition of extra propagating degrees of freedom on cosmological backgrounds, and exhibit self tuning to bring a large cosmological constant under control. This nonlinear approach leads to new properties that may be instructive for exploring the behaviors of gravity.
New Agegraphic Dark Energy in $f(R)$ Gravity
M. R. Setare
2009-08-03T23:59:59.000Z
In this paper we study cosmological application of new agegraphic dark energy density in the $f(R)$ gravity framework. We employ the new agegraphic model of dark energy to obtain the equation of state for the new agegraphic energy density in spatially flat universe. Our calculation show, taking $nnew agegraphic dark energy model in flat universe in the modified gravity cosmology framework. Also we develop a reconstruction scheme for the modified gravity with $f(R)$ action.
Solar System experiments do not yet veto modified gravity models
Valerio Faraoni
2006-07-05T23:59:59.000Z
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.
The f(R) Gravity Function of the Linde Quintessence
Sergei V. Ketov; Natsuki Watanabe
2014-10-20T23:59:59.000Z
We calculate the f(R) gravity function in the dual gravity description of the quintessence model with a quadratic (Linde) scalar potential and a positive cosmological constant. We find that in the large curvature regime relevant to chaotic inflation in early Universe, the dual f(R) gravity is well approximated by the (matter) loop-corrected Starobinsky inflationary model. In the small curvature regime relevant to dark energy in the present Universe, the f(R) gravity function reduces to the Einstein-Hilbert one with a positive cosmological constant.
Ground Gravity Survey At Lake City Hot Springs Area (Warpinski...
fault zones. The focus of Lake City Geothermal's current effort is on enhancing the site interpretation by re-evaluating the existing seismic data, conducting a detailed gravity...
Unification of Gravity and Electromagnetism II A Geometric Theory
Partha Ghose
2015-02-11T23:59:59.000Z
It is shown that unification of gravity and electromagnetism can be achieved using an affine non-symmetric connection $\\Gamma^\\lambda_{\\mu\
Summary of Session A6: Alternative Theories of Gravity
R. B. Mann
1998-03-13T23:59:59.000Z
This is a summary of the workshop A.6 on Alternative Theories of Gravity, prepared for the proceedings for the GR15 conference.
Quantized gauge-affine gravity in the superfiber bundle approach
A. Meziane; M. Tahiri
2005-11-10T23:59:59.000Z
The quantization of gauge-affine gravity within the superfiber bundle formalism is proposed. By introducing an even pseudotensorial 1-superform over a principal superfibre 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 to the Poincare group double-covering 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.
Review of Lattice Supersymmetry and Gauge-Gravity Duality
Joseph, Anosh
2015-01-01T23:59:59.000Z
We review the status of recent investigations on validating the gauge-gravity duality conjecture through numerical simulations of strongly coupled maximally supersymmetric thermal gauge theories. In the simplest setting, the gauge-gravity duality connects systems of D0-branes and black hole geometries at finite temperature to maximally supersymmetric gauged quantum mechanics at the same temperature. Recent simulations show that non-perturbative gauge theory results give excellent agreement with the quantum gravity predictions, thus proving strong evidence for the validity of the duality conjecture and more insight into quantum black holes and gravity.
Parameterized post-Newtonian limit of Horndeski's gravity theory
Manuel Hohmann
2015-08-20T23:59:59.000Z
We present a recent result on the parameterized post-Newtonian (PPN) limit of Horndeski's gravity theory and its consistency with solar system observations.
Ground Gravity Survey At Under Steamboat Springs Area (Warpinski...
Under Steamboat Springs Area (Warpinski, Et Al., 2004) Exploration Activity Details Location Under Steamboat Springs Area Exploration Technique Ground Gravity Survey Activity Date...
Ground Gravity Survey At San Francisco Volcanic Field Area (Warpinski...
Francisco Volcanic Field Area (Warpinski, Et Al., 2004) Exploration Activity Details Location San Francisco Volcanic Field Area Exploration Technique Ground Gravity Survey Activity...
Costs of Imported Crude Oil by API Gravity
Gasoline and Diesel Fuel Update (EIA)
"Monthly Foreign Crude Oil Acquisition Report," July 1984 to present. 26. F.O.B. Costs of Imported Crude Oil by API Gravity 48 Energy Information Administration Petroleum...
Review of Lattice Supersymmetry and Gauge-Gravity Duality
Anosh Joseph
2015-09-04T23:59:59.000Z
We review the status of recent investigations on validating the gauge-gravity duality conjecture through numerical simulations of strongly coupled maximally supersymmetric thermal gauge theories. In the simplest setting, the gauge-gravity duality connects systems of D0-branes and black hole geometries at finite temperature to maximally supersymmetric gauged quantum mechanics at the same temperature. Recent simulations show that non-perturbative gauge theory results give excellent agreement with the quantum gravity predictions, thus proving strong evidence for the validity of the duality conjecture and more insight into quantum black holes and gravity.
Interfacial gravity currents. I. Mixing and entrainment B. R. Sutherland
Sutherland, Bruce
Interfacial gravity currents. I. Mixing and entrainment B. R. Sutherland Department of Mathematical energy are compared with theories that neglect mixing and entrainment processes. As the middle layer
Integration of Full Tensor Gravity and ZTEM Passive Low Frequency...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
and ZTEM Passive Low Frequency EM Instruments for Simultaneous Data Acquisition Integration of Full Tensor Gravity and ZTEM Passive Low Frequency EM Instruments for...
Strong and weak gravitational field in $R+?^4/R$ gravity
Kh. Saaidi; A. Vajdi; S. W. Rabiei; A. Aghamohammadi; H. Sheikhahmadi
2012-01-18T23:59:59.000Z
We introduce a new approach for investigating the weak field limit of vacuum field equations in $f(R)$ gravity and we find the weak field limit of $f(R)=R+\\mu ^4/R$ gravity. Furthermore, we study the strong gravity regime in $R+\\mu^{4}/R$ model of $f(R)$ gravity. We show the existence of strong gravitational field in vacuum for such model. We find out in the limit $\\mu\\rightarrow 0$, the weak field limit and the strong gravitational field can be regarded as a perturbed Schwarzschild metric.
Ground Gravity Survey At Blue Mountain Geothermal Area (Fairbank...
Ground Gravity Survey At Blue Mountain Geothermal Area (Fairbank Engineering Ltd, 2003) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground...
Dynamical stability of Minkowski space in higher order gravity
Petr V. Tretyakov
2015-05-19T23:59:59.000Z
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 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. It was shown that in the case of $f(R)$ gravity Minkowski solution asymptotically stable in ghost-free ($f'>0$) and tachyon-free ($f">0$) theories in expanding Universe with respect to isotropic and basic anisotropic perturbations. In the case of higher order gravity with $\\alpha R\\Box R$ correction conditions of Minkowski stability with respect to isotropic perturbations significantly different: $f'(0)0$. And in the case of scalar-tensor gravity with non-minimal kinetic coupling Minkowski solution asymptotically stable in expanding Universe with respect to isotropic perturbations of metric. Moreover the developed method may be used for finding additional restrictions on parameters of different modified gravity theories.
Ground Gravity Survey At Dixie Valley Geothermal Area (Allis...
2000) Exploration Activity Details Location Dixie Valley Geothermal Area Exploration Technique Ground Gravity Survey Activity Date 1999 - 2000 Usefulness not indicated DOE-funding...
Covariant Symplectic Structure and Conserved Charges of Topologically Massive Gravity
Caner Nazaroglu; Yavuz Nutku; Bayram Tekin
2011-06-07T23:59:59.000Z
We present the covariant symplectic structure of the Topologically Massive Gravity and find a compact expression for the conserved charges of generic spacetimes with Killing symmetries.
Exercise protocols during short-radius centrifugation for artificial gravity
Edmonds, Jessica Leigh
2008-01-01T23:59:59.000Z
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 ...
Competition and Reliability in North American Electricity Markets...
Electricity Markets Technical Workshop Competition and Reliability in North American Electricity Markets Technical Workshop Competition and Reliability in North American...
Moral pressure : American democracy and Chinese human rights
Chan, Stephanie Tze-Hua
2011-01-01T23:59:59.000Z
of the Sino-American agreement on nuclear cooperation, andof the Sino-American agreement on nuclear cooperation, and
Ponce, V. Miguel
American Statistical Association Names Fellows for 2010 ALEXANDRIA VA (PRWEB) MAY 20, 2010 The American Statistical Association (ASA), the nation's preeminent professional statistical society, today the American Statistical Association The American Statistical Association (ASA), a scientific and educational
Hawkins, Torrance N.
2006-04-12T23:59:59.000Z
between African American and European American students? 2. Is there a significant difference in verve levels of African American male and African American female students in middle school? 3. Is there a significant difference in the academic achievement...
Effective Levi-Civita Dilaton theory from Metric Affine Dilaton Gravity
R. Scipioni
1999-05-25T23:59:59.000Z
We show how a Metric Affine theory of Dilaton gravity can be reduced to an effective Riemannian Dilaton gravity model. A simple generalization of the Obukhov-Tucker-Wang theorem to Dilaton gravity is then presented.
American Valve: Order (2010-CW-1411)
Broader source: Energy.gov [DOE]
DOE ordered American Valve, Inc. to pay a $5,000 civil penalty after finding American Valve had failed to certify that certain showerhead models comply with the applicable water conservation standards.
American Ag Fuels LLC | Open Energy Information
American Ag Fuels LLC Place: Defiance, Ohio Zip: 43512 Product: Biodiesel producer in Defiance, Ohio. References: American Ag Fuels LLC1 This article is a stub. You can help...
Dissertations Recently Completed on Latin American Theatre
1980-04-01T23:59:59.000Z
4 LATIN AMERICAN THEATRE REVIEW Dissertations Recently Completed on Latin American Theatre Ascarrunz-Gilman, Graciela. "El sentido religioso del teatro de Carlos Solór- zano." (California, Davis) Bixler, Jacqueline Eyring. "Theory and Technique...
American Statistical Association National Science Foundation
Bermúdez, José Luis
American Statistical Association National Science Foundation U.S. Census Bureau ASA American Statistical Association 732 North Washington Street Alexandria, VA 22314-1943 U.S. government and analysis, statistical methodology and computing, information and behavioral science, and geography
Information Technology: American National Standard for Information
Information Technology: American National Standard for Information Systems-- Data Format 500-275 Information Technology: American National Standard for Information Systems-- Data Format Coleman, and Patrice Yuh, Editors Sponsored by Information Access Division Information Technology
Information Technology: American National Standard for
Information Technology: American National Standard for Information Systems-- Data Format Publication 500-245 Information Technology: American National Standard for Information Systems-- Data Format for the Interchange of Fingerprint, Facial, & Scar Mark & Tattoo (SMT) Information Sponsored by Information Technology
Information Technology: American National Standard for Information
Information Technology: American National Standard for Information Systems-- Data Format-271 Information Technology: American National Standard for Information Systems-- Data Format for the Interchange Sponsored by Information Access Division Information Technology Laboratory National Institute of Standards
Modern Latin American History History 315
Fletcher, Robin
; interviews; pamphlets; personal narratives; sources; speeches mexico and revolution and sources #12;2 Also.utexas.edu/la/region/history/ Latin American Pamphlet Digital Collection hcl.harvard.edu/collections/digital_collections/latin_american_pamphlets
Heart Healthy Home Cooking African American Style
Bandettini, Peter A.
Heart Healthy Home Cooking African American Style With Every Heartbeat Is Life #12;#12;Heart Recipe Substitutions for Heart Healthy Cooking at the heart of African American family life and special celebrations. This recipe book brings together many
North American Leaders Summit: Energy Deliverables | Department...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
discussions at the North American Leaders Summit, to be held in Guadalajara, Mexico, on August 9-10, 2009. Building on the work of the North American Energy Working...
American Range: Order (2014-CE-23006)
Broader source: Energy.gov [DOE]
DOE ordered American Range Corporation to pay a $8,000 civil penalty after finding American Range had failed to certify that certain models of cooking products comply with the applicable energy conservation standards.
Quantum Gravito-Optics: A Light Route from Semiclassical Gravity to Quantum Gravity
C. S. Unnikrishnan; George T. Gillies
2015-08-03T23:59:59.000Z
Quantum gravity remains an elusive theory, in spite of our thorough understanding of the quantum theory and the general theory of relativity separately, presumably due to the lack of any observational clues. We argue that the theory of quantum gravity has a strong constraining anchor in the sector of gravitational radiation ensuring reliable physical clues, albeit in a limited observable form. In particular, all types of gravitational waves expected to be observable in LIGO-like advanced detectors are fully quantum mechanical states of radiation. Exact equivalence of the full quantum gravity theory with the familiar semiclassical theory is ensured in the radiation sector, in most real situations where the relevant quantum operator functions are normal ordered, by the analogue of the optical equivalence theorem in quantum optics. We show that this is indeed the case for detection of the waves from a massive binary system, a single gravitational atom, that emits coherent radiation. The idea of quantum-gravitational optics can assist in guiding along the fuzzy roads to quantum gravity.
TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY
Willenbring, Jeb F.
fellowship. c 2002 American Mathematical Society 4393 #12;4394 JEB F. WILLENBRING on V , under the usual
Honda: North American Manufacturing Facilities | Department of...
Broader source: Energy.gov (indexed) [DOE]
From October, 2008 Honda: North American Manufacturing Facilities More Documents & Publications Johnson Controls: EISA Presentation MEMA: Comments AZ Automotive...
NATIVE AMERICAN HISTORY Libby R. Tronnes
Wisconsin at Madison, University of
, and Demography" CAIH (2002) Indians in the American South Post-Contact Gallay, Alan. The Indian Slave Trade
Drag phenomena from holographic massive gravity
Matteo Baggioli; Daniel K. Brattan
2015-04-28T23:59:59.000Z
We consider the motion of point particles in a strongly coupled field theory with broken translation invariance. We obtain the energy and momentum loss rates and drag coefficients for a class of such particles by solving for the motion of classical strings in holographic massive gravity. At low temperatures compared to the graviton mass the behaviour of the string is controlled by the appearance of an exotic ground state with non-zero entropy at zero temperature. Additionally we find an upper bound on the diffusion constant for a collection of these particles which is saturated when the mass of the graviton goes to zero.
Drag phenomena from holographic massive gravity
Baggioli, Matteo
2015-01-01T23:59:59.000Z
We consider the motion of point particles in a strongly coupled field theory with broken translation invariance. We obtain the energy and momentum loss rates and drag coefficients for a class of such particles by solving for the motion of classical strings in holographic massive gravity. At low temperatures compared to the graviton mass the behaviour of the string is controlled by the appearance of an exotic ground state with non-zero entropy at zero temperature. Additionally we find an upper bound on the diffusion constant for a collection of these particles which is saturated when the mass of the graviton goes to zero.
Gravity can be neither classical nor quantized
Sabine Hossenfelder
2012-12-03T23:59:59.000Z
I argue that it is possible for a theory to be neither quantized nor classical. We should therefore give up the assumption that the fundamental theory which describes gravity at shortest distances must either be quantized, or quantization must emerge from a fundamentally classical theory. To illustrate my point I will discuss an example for a theory that is neither classical nor quantized, and argue that it has the potential to resolve the tensions between the quantum field theories of the standard model and general relativity.
Hall viscosity from gauge/gravity duality
Omid Saremi; Dam Thanh Son
2011-03-24T23:59:59.000Z
In (2+1)-dimensional systems with broken parity, there exists yet another transport coefficient, appearing at the same order as the shear viscosity in the hydrodynamic derivative expansion. In condensed matter physics, it is referred to as "Hall viscosity". We consider a simple holographic realization of a (2+1)-dimensional isotropic fluid with broken spatial parity. Using techniques of fluid/gravity correspondence, we uncover that the holographic fluid possesses a nonzero Hall viscosity, whose value only depends on the near-horizon region of the background. We also write down a Kubo's formula for the Hall viscosity. We confirm our results by directly computing the Hall viscosity using the formula.
A new quasidilaton theory of massive gravity
Shinji Mukohyama
2014-10-08T23:59:59.000Z
We present a new quasidilaton theory of Poincare invariant massive gravity, based on the recently proposed framework of matter coupling that makes it possible for the kinetic energy of the quasidilaton scalar to couple to both physical and fiducial metrics simultaneously. We find a scaling-type exact solution that expresses a self-accelerating de Sitter universe, and then analyze linear perturbations around it. It is shown that in a range of parameters all physical degrees of freedom have non-vanishing quadratic kinetic terms and are stable in the subhorizon limit, while the effective Newton's constant for the background is kept positive.
Static wormholes in vacuum for conformal gravity
Julio Oliva; David Tempo; Ricardo Troncoso
2009-07-07T23:59:59.000Z
A static spherically symmetric wormhole solution for conformal gravity in vacuum is found. The solution possesses a single integration constant which determines the size of the neck connecting two static homogeneous universes of constant spatial curvature. Time runs at different rates on each side of the neck, and depending on the value of the parameter, the wormhole can develop a cosmological horizon only at one side. It is shown that the wormholes correspond to the matching of different Einstein spacetimes by means of improper conformal transformations.
Null Energy Condition violations in bimetric gravity
Baccetti, Valentina; Visser, Matt
2012-01-01T23:59:59.000Z
We consider the effective stress-energy tensors for the foreground and background sectors in ghost-free bimetric gravity. By considering the symmetries of the theory, we show that the foreground and background null energy conditions (NECs) are strongly anti-correlated. In particular, the NECs can only be simultaneously fulfilled when they saturate, corresponding to foreground and background cosmological constants. In all other situations, either the foreground or the background is subject to a NEC-violating contribution to the total stress-energy.
Gamma Ray Burst Neutrinos Probing Quantum Gravity
M. C. Gonzalez-Garcia; F. Halzen
2006-11-28T23:59:59.000Z
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.
Dynamics of generalized Palatini theories of gravity
Vitagliano, Vincenzo; Liberati, Stefano [SISSA-International School for Advanced Studies, Via Bonomea 265, 34136 Trieste (Italy) and INFN sezione di Trieste, sezione di Trieste, via Valerio 2, 34127 Trieste (Italy); Sotiriou, Thomas P. [Department of Applied Mathematics and Theoretical Physics, Center for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)
2010-10-15T23:59:59.000Z
It is known that in f(R) theories of gravity with an independent connection which can be both nonmetric and nonsymmetric, this connection can always be algebraically eliminated in favor of the metric and the matter fields, so long as it is not coupled to the matter explicitly. We show here that this is a special characteristic of f(R) actions, and it is not true for actions that include other curvature invariants. This contradicts some recent claims in the literature. We clarify the reasons for this contradiction.
Loop Quantum Gravity: An Inside View
Thomas Thiemann
2006-08-29T23:59:59.000Z
This is a (relatively) non -- technical summary of the status of the quantum dynamics in Loop Quantum Gravity (LQG). We explain in detail the historical evolution of the subject and why the results obtained so far are non -- trivial. The present text can be viewed in part as a response to an article by Nicolai, Peeters and Zamaklar [hep-th/0501114]. We also explain why certain no go conclusions drawn from a mathematically correct calculation in a recent paper by Helling et al [hep-th/0409182] are physically incorrect.
A high frequency resonance gravity gradiometer
Bagaev, S. N.; Kvashnin, N. L.; Skvortsov, M. N. [Laser Physics Institute SB RAS, Novosibirsc (Russian Federation); Bezrukov, L. B.; Krysanov, V. A. [Institute of Nuclear Physics RAS, Moscow (Russian Federation); Oreshkin, S. I.; Motylev, A. M.; Popov, S. M.; Samoilenko, A. A.; Yudin, I. S. [Lomonosov MSU, Sternberg Astronomical Institute, Moscow (Russian Federation); Rudenko, V. N. [Institute of Nuclear Physics RAS, Moscow (Russian Federation); Lomonosov MSU, Sternberg Astronomical Institute, Moscow (Russian Federation)
2014-06-15T23:59:59.000Z
A new setup OGRAN—the large scale opto-acoustical gravitational detector is described. As distinguished from known gravitational bar detectors it uses the optical interferometrical readout for registering weak variations of gravity gradient at the kilohetz frequency region. At room temperature, its sensitivity is limited only by the bar Brownian noise at the bandwidth close to 100 Hz. It is destined for a search for rare events—gravitational pulses coincident with signals of neutrino scintillator (BUST) in the deep underground of Baksan Neutrino Observatory of INR RAS.
Confronting Dilaton-exchange gravity with experiments
H. V. Klapdor-Kleingrothaus; H. Päs; U. Sarkar
2000-08-16T23:59:59.000Z
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.
Seven-dimensional gravity with topological terms
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
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.
Anisotropic higher derivative gravity and inflationary universe
W. F. Kao
2006-05-21T23:59:59.000Z
Stability analysis of the Kantowski-Sachs type universe in pure higher derivative gravity theory is studied in details. The non-redundant generalized Friedmann equation of the system is derived by introducing a reduced one dimensional generalized KS type action. This method greatly reduces the labor in deriving field equations of any complicate models. Existence and stability of inflationary solution in the presence of higher derivative terms are also studied in details. Implications to the choice of physical theories are discussed in details in this paper.
Inflationary Universe in Higher Derivative Induced Gravity
W. F. Kao
2000-06-27T23:59:59.000Z
In an induced-gravity model, the stability condition of an inflationary slow-rollover solution is shown to be $\\phi_0 \\partial_{\\phi_0}V(\\phi_0)=4V(\\phi_0)$. The presence of higher derivative terms will, however, act against the stability of this expanding solution unless further constraints on the field parameters are imposed. We find that these models will acquire a non-vanishing cosmological constant at the end of inflation. Some models are analyzed for their implication to the early universe.
American Elements | Open Energy Information
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 DeliciousPlasmaP a gHigh4-FD-a <Alaska Underground StorageAlternativeJump to: navigation, searchAmericanAmerican
Leonard Wood and the American Empire
Pruitt, James Herman
2012-07-16T23:59:59.000Z
During the ten years following the Spanish American War (1898 to 1908), Major General Leonard Wood served as the primary agent of American imperialism. Wood was not only a proconsul of the new American Empire; he was a symbol of the empire...
Economic Impact of the American Clean Energy
Mohaghegh, Shahab
Economic Impact of the American Clean Energy and Security Act of 2009 on the West Virginia Economy ........................................................................................................................ 1 American Clean Energy and Security Act of 2009 at reducing greenhouse gas emissions. This report examines the impact of the American Clean Energy
The early American motion picture industry: promoting American cultural hegemony
Wier, Theresa Joanne
1994-01-01T23:59:59.000Z
For the American motion picture industry, a key period in its development was that which followed World War I until the advent of the techonology of sound film. Film occupied a unique position during this period, as both a product and promoter...
Moho topography beneath the Corinth Rift area (Greece) from inversion of gravity data
Demouchy, Sylvie
Moho topography beneath the Corinth Rift area (Greece) from inversion of gravity data C. Tiberi,1 to Miocene lithospheric instabilities. Key words: boudinage, continental rifts, gravity inversion, Greece
Biodiesel ASTM Update and Future Technical Needs | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
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 Delicious RankShale_Gas.pdfService on the TargetFY12Environment |BethelHydrocarbons |Bio-Oil Deployment inE b ay nai
Biodiesel Progress: ASTM Specifications and 2nd Generation Biodiesel |
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
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 Delicious RankShale_Gas.pdfService on the TargetFY12Environment |BethelHydrocarbons |Bio-Oil Deployment
Microsoft PowerPoint - AAVP.ASTM.Monterey..ppt
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), 2002; Level:5 TablesExports(Journal Article)41clothThe Bonneville PowerTariff Pages default SignEnergy Michigan: General D t A l t Ni Ni8Sh t T d WitepBimodalARM
Synoptic Responses to Mountain Gravity Waves Encountering Directional Critical Levels
Lott, Francois
Synoptic Responses to Mountain Gravity Waves Encountering Directional Critical Levels ARMEL MARTIN the synoptic response to mountain gravity waves (GWs) absorbed at directional critical levels. The model in the midtroposphere. First, the authors consider the case of an idealized mountain range such that the orographic
Cosmological evolutions of $F(R)$ nonlinear massive gravity
De-Jun Wu
2014-03-24T23:59:59.000Z
Recently a new extended nonlinear massive gravity model has been proposed which includes the $F(R)$ modifications to dRGT model.We follow the $F(R)$ nonlinear massive gravity and study its implications on cosmological evolutions. We derive the critical points of the cosmic system and study the corresponding kinetics by performing the phase-plane analysis.
On coupling NEC-violating matter to gravity
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Chatterjee, Saugata; Parikh, Maulik; van der Schaar, Jan Pieter
2015-05-01T23:59:59.000Z
We show that effective theories of matter that classically violate the null energy condition cannot be minimally coupled to Einstein gravity without being inconsistent with both string theory and black hole thermodynamics. We argue however that they could still be either non-minimally coupled or coupled to higher-curvature theories of gravity.
18 Maple Syrup Digest HIGH VACUUM IN GRAVITY TUBING
Hayden, Nancy J.
where elec- tricity is not available, time needed for maintenance of a pump and extractor gravity tubing, or tubing without the use of a pump, to be a poor substitute for a modern system with a pump, extractor, and the latest tubing arrangement. Sap yields from gravity systems are often half
Gravity Field and Internal Structure of Mercury from MESSENGER
Zuber, Maria
,5 Mark E. Perry,11 David D. Rowlands,5 Sander Goossens,12 James W. Head,13 Anthony H. Taylor14 RadioGravity Field and Internal Structure of Mercury from MESSENGER David E. Smith,1 Maria T. Zuber,1 tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern
Wavelet based inversion of gravity data Fabio Boschetti
Boschetti, Fabio
1 Wavelet based inversion of gravity data Fabio Boschetti CSIRO Exploration & Mining and Australian Running Heading: Wavelet based inversion of gravity data #12;2 ABSTRACT The Green's function of the Poisson equation, and its spatial derivatives, lead to a family of wavelets specifically tailored
Motion in alternative theories of gravity
Gilles Esposito-Farese
2009-05-15T23:59:59.000Z
Although general relativity (GR) passes all present experimental tests with flying colors, it remains important to study alternative theories of gravity for several theoretical and phenomenological reasons that we recall in these lecture notes. The various possible ways of modifying GR are presented, and we notably show that the motion of massive bodies may be changed even if one assumes that matter is minimally coupled to the metric as in GR. This is illustrated with the particular case of scalar-tensor theories of gravity, whose Fokker action is discussed, and we also mention the consequences of the no-hair theorem on the motion of black holes. The finite size of the bodies modifies their motion with respect to pointlike particles, and we give a simple argument showing that the corresponding effects are generically much larger in alternative theories than in GR. We also discuss possible modifications of Newtonian dynamics (MOND) at large distances, which have been proposed to avoid the dark matter hypothesis. We underline that all the previous classes of alternatives to GR may a priori be used to predict such a phenomenology, but that they generically involve several theoretical and experimental difficulties.
Canonical Quantum Gravity on Noncommutative Spacetime
Martin Kober
2014-09-04T23:59:59.000Z
In this paper canonical quantum gravity on noncommutative space-time is considered. The corresponding generalized classical theory is formulated by using the moyal star product, which enables the representation of the field quantities depending on noncommuting coordinates by generalized quantities depending on usual coordinates. But not only the classical theory has to be generalized in analogy to other field theories. Besides, the necessity arises to replace the commutator between the gravitational field operator and its canonical conjugated quantity by a corresponding generalized expression on noncommutative space-time. Accordingly the transition to the quantum theory has also to be performed in a generalized way and leads to extended representations of the quantum theoretical operators. If the generalized representations of the operators are inserted to the generalized constraints, one obtains the corresponding generalized quantum constraints including the Hamiltonian constraint as dynamical constraint. After considering quantum geometrodynamics under incorporation of a coupling to matter fields, the theory is transferred to the Ashtekar formalism. The holonomy representation of the gravitational field as it is used in loop quantum gravity opens the possibility to calculate the corresponding generalized area operator.
New ground state for quantum gravity
Joao Magueijo; Laura Bethke
2012-07-03T23:59:59.000Z
In this paper we conjecture the existence of a new "ground" state in quantum gravity, supplying a wave function for the inflationary Universe. We present its explicit perturbative expression in the connection representation, exhibiting the associated inner product. The state is chiral, dependent on the Immirzi parameter, and is the vacuum of a second quantized theory of graviton particles. We identify the physical and unphysical Hilbert sub-spaces. We then contrast this state with the perturbed Kodama state and explain why the latter can never describe gravitons in a de Sitter background. Instead, it describes self-dual excitations, which are composites of the positive frequencies of the right-handed graviton and the negative frequencies of the left-handed graviton. These excitations are shown to be unphysical under the inner product we have identified. Our rejection of the Kodama state has a moral tale to it: the semi-classical limit of quantum gravity can be the wrong path for making contact with reality (which may sometimes be perturbative but nonetheless fully quantum). Our results point towards a non-perturbative extension, and we present some conjectures on the nature of this hypothetical state.
Dipole gravity waves from unbound quadrupoles
Felber, Franklin
2010-01-01T23:59:59.000Z
Dipole gravitational disturbances from gravitationally unbound mass quadrupoles propagate to the radiation zone with signal strength at least of quadrupole order if the quadrupoles are nonrelativistic, and of dipole order if relativistic. Angular distributions of parallel-polarized and transverse-polarized dipole power in the radiation zone are calculated for simple unbound quadrupoles, like a linear-oscillator/stress-wave pair and a particle storage ring. Laboratory tests of general relativity through measurements of dipole gravity waves in the source region are proposed. A NASA G2 flywheel module with a modified rotor can produce a post-Newtonian dc bias signal at a gradiometer up to 1 mE. At peak luminosity, the repulsive dipole impulses of proton bunches at the LHC can produce an rms velocity of a high-Q detector surface up to 4 micron/s. Far outside the source region, Newtonian lunar dipole gravity waves can produce a 1-cm displacement signal at LISA. Dipole signal strengths of astrophysical events invol...
Dipole gravity waves from unbound quadrupoles
Franklin Felber
2010-06-10T23:59:59.000Z
Dipole gravitational disturbances from gravitationally unbound mass quadrupoles propagate to the radiation zone with signal strength at least of quadrupole order if the quadrupoles are nonrelativistic, and of dipole order if relativistic. Angular distributions of parallel-polarized and transverse-polarized dipole power in the radiation zone are calculated for simple unbound quadrupoles, like a linear-oscillator/stress-wave pair and a particle storage ring. Laboratory tests of general relativity through measurements of dipole gravity waves in the source region are proposed. A NASA G2 flywheel module with a modified rotor can produce a post-Newtonian dc bias signal at a gradiometer up to 1 mE. At peak luminosity, the repulsive dipole impulses of proton bunches at the LHC can produce an rms velocity of a high-Q detector surface up to 4 micron/s. Far outside the source region, Newtonian lunar dipole gravity waves can produce a 1-cm displacement signal at LISA. Dipole signal strengths of astrophysical events involving unbound quadrupoles, like near collisions and neutron star kicks in core-collapse supernovae, are estimated.
Spherically symmetric conformal gravity and "gravitational bubbles"
V. A. Berezin; V. I. Dokuchaev; Yu. N. Eroshenko
2014-12-09T23:59:59.000Z
The general structure of the spherically symmetric solutions in the Weyl conformal gravity is described. The corresponding Bach equation are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions is found. It consists of two classes. The first one contains the solutions with constant two-dimensional curvature scalar of our specific metrics, and the representatives are the famous Robertson-Walker metrics. One of them we called the "gravitational bubbles", which is compact and with zero Weyl tensor. The second class is more general, with varying curvature scalar. We found its representative as the one-parameter family. It appears that it can be conformally covered by the thee-parameter Mannheim-Kazanas solution. We also investigated the general structure of the energy-momentum tensor in the spherical conformal gravity and constructed the vectorial equation that reveals clearly the same features of non-vacuum solutions. One of them, the metrics a la Vaidya, is explicitly written.
Vacuum energy: quantum hydrodynamics vs quantum gravity
G. E. Volovik
2005-09-09T23:59:59.000Z
We compare quantum hydrodynamics and quantum gravity. They share many common features. In particular, both have quadratic divergences, and both lead to the problem of the vacuum energy, which in the quantum gravity transforms to the cosmological constant problem. We show that in quantum liquids the vacuum energy density is not determined by the quantum zero-point energy of the phonon modes. The energy density of the vacuum is much smaller and is determined by the classical macroscopic parameters of the liquid including the radius of the liquid droplet. In the same manner the cosmological constant is not determined by the zero-point energy of quantum fields. It is much smaller and is determined by the classical macroscopic parameters of the Universe dynamics: the Hubble radius, the Newton constant and the energy density of matter. The same may hold for the Higgs mass problem: the quadratically divergent quantum correction to the Higgs potential mass term is also cancelled by the microscopic (trans-Planckian) degrees of freedom due to thermodynamic stability of the whole quantum vacuum.
sourced steam coal burnt in power plants in the northeastern portion of the United States. As coal mining of electrical power from Canada appears to have little impact on the production of steam coal in VirginiaNorth American Cross-Border Electricity Trade Ian M. Loomis Virginia Center for Coal and Energy
National Museum of American History
Miller, Scott
National Museum of American History Strategic Plan 2013--2018 #12;Contents Looking Ahead 2 Mission Funding the Plan 12 Coda 15 A Tagline to Remember 16 Milestones 17 Credits 21 Love History. Use History. Make History. #12;Mission Through incomparable collections, rigorous research, and dynamic public
2012 Fellow American Geophysical Union
Kurapov, Alexander
) are critical to the intensity of ocean currents, to long- and short-term climate variations, and the health2012 Fellow American Geophysical Union James Moum, professor in the College of Earth, Ocean contributions to our understanding of ocean mixing in coastal, abyssal and Equatorial regimes using innovative
September 2010 American Recovery and
Oak Ridge National Laboratory
September 2010 i American Recovery and Reinvestment Act (ARRA) FEMP Technical Assistance U.S. Naval by applying GSHP systems. The current HVAC system for the building is a conventional Air Handling Unit (AHU) system with chiller. The heating and the DHW are provided by district steam. The building is close
QER- Comment of American Water
Broader source: Energy.gov [DOE]
Dear QER Team; Thank you for the opportunity to provide comments to the Quadrennial Energy Review Task Force to discuss the water and energy nexus, advances in water innovative technologies, and the impact of climate change on water issues. On behalf of American Water, I wish to submit the following White Papers which we have prepared on these critical issues: Innovations in Energy Use Sustainability and Resiliency Planning for Water Utilities One Water Water/Energy Correlation The Value of Water Challenges in the Water Industry: Climate Change Challenges in the Water Industry: Meeting Demand in the West Innovation Solutions Within the Water Industry: Desalination Innovation Solutions Within the Water Industry: Going Green Innovation Solutions Within the Water Industry: Water Reuse Bridging the Water Innovation Gap. Founded in 1886, American Water is the largest publicly traded U.S. water and wastewater utility company. With headquarters in Voorhees, NJ, the company employs approximately 6,600 dedicated professionals who provide drinking water, wastewater and other related services to an estimated 14 million people in more than 40 states. Please feel free to contact me if you have any questions or if there is any way American Water can be helpful to your mission. Respectfully Yours, Martin (See attached file: White Papers.pdf) Martin D. Kerckhoff Vice President and Divisional General Counsel Central Division American Water CONFIDENTIAL & PRIVILEGED COMMUNICATION This email and any attachments hereto constitute a legally confidential communication from the Legal Department of American Water. The information contained herein is subject to attorney-client privilege and is for the sole use of the intended original addressee. If you are not the intended original addressee, you are hereby notified that any reading, disclosure, copying, distribution, use, or taking of any action in reliance on the contents contained herein is strictly prohibited. If you have received this message in error, please immediately notify us at 314.966.2241 and delete this message from your system. WARNING: Although American Water has taken reasonable precautions to ensure that no viruses are present in this email, it is the responsibility of the recipient to ensure that it is virus free. No responsibility is accepted by American Water for any loss or damage arising in any way from the receipt and/or use of this email.
Qiang, Li-E
2015-01-01T23:59:59.000Z
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
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.
Bending of light in conformal Weyl gravity
Sultana, Joseph; Kazanas, Demosthenes [Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States) and Department of Mathematics, University of Malta, Msida (Malta); Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)
2010-06-15T23:59:59.000Z
We reexamine the bending of light issue associated with the metric of the static, spherically symmetric solution of Weyl gravity discovered by Mannheim and Kazanas (1989). To this end we employ the procedure used recently by Rindler and Ishak to obtain the bending angle of light by a centrally concentrated spherically symmetric matter distribution in a Schwarzschild-de Sitter background. In earlier studies the term {gamma}r in the metric led to the paradoxical result of a bending angle proportional to the photon impact parameter, when using the usual formalism appropriate to asymptotically flat space-times. However, employing the approach of light bending of Rindler and Ishak we show that the effects of this term are in fact insignificant, with the discrepancy between the two procedures attributed to the definition of the bending angle between the asymptotically flat and nonflat spaces.
What is Dynamics in Quantum Gravity?
Malkiewicz, Przemyslaw
2015-01-01T23:59:59.000Z
Dynamics of general relativistic systems is given with respect to internal clocks. We investigate the extent to which the choice of internal clock in quantum description of the gravitational field determines the quantum dynamics. We develop our method by making use of the Hamilton-Jacobi theory, which is extended to include time coordinate transformations. Next, we apply our method to a quantum model of the flat Friedmann universe and compute some clock-induced deviations to semiclassical phase space portrait. Within a fixed quantization we find the abundance of possible semiclassical extensions to general relativity by switching between clocks. It follows that quantities like minimal volume, maximal curvature and even a number of quantum bounces, often used to describe quantum effects in gravity, are ill-defined.
What is Dynamics in Quantum Gravity?
Przemyslaw Malkiewicz
2015-05-18T23:59:59.000Z
Dynamics of general relativistic systems is given with respect to internal clocks. We investigate the extent to which the choice of internal clock in quantum description of the gravitational field determines the quantum dynamics. We develop our method by making use of the Hamilton-Jacobi theory, which is extended to include time coordinate transformations. Next, we apply our method to a quantum model of the flat Friedmann universe and compute some clock-induced deviations to semiclassical phase space portrait. Within a fixed quantization we find the abundance of possible semiclassical extensions to general relativity by switching between clocks. It follows that quantities like minimal volume, maximal curvature and even a number of quantum bounces, often used to describe quantum effects in gravity, are ill-defined.
Phenomenologically viable Lorentz-violating quantum gravity
Sotiriou, Thomas; Weinfurtner, Silke
2009-01-01T23:59:59.000Z
Horava's "Lifschitz point gravity" has many desirable features, but in its original incarnation one is forced to accept a non-zero cosmological constant of the wrong sign to be compatible with observation. We develop an extension of Horava's model that abandons "detailed balance", and in 3+1 dimensions exhibit all five marginal (renormalizable) and four relevant (super-renormalizable) operators, as determined by power counting. We also consider the classical limit of this theory, evaluate the Hamiltonian and super-momentum constraints, and extract the classical equations of motion in a form similar to the ADM formulation of general relativity. This puts the model in a framework amenable to developing detailed precision tests.
Nonsingular cosmology from evolutionary quantum gravity
Francesco Cianfrani; Giovanni Montani; Fabrizio Pittorino
2014-10-30T23:59:59.000Z
We provide a cosmological implementation of the evolutionary quantum gravity, describing an isotropic Universe, in the presence of a negative cosmological constant and a massive (preinflationary) scalar field. We demonstrate that the considered Universe has a nonsingular quantum behavior, associated to a primordial bounce, whose ground state has a high occupation number. Furthermore, in such a vacuum state, the super-Hamiltonian eigenvalue is negative, corresponding to a positive emerging dust energy density. The regularization of the model is performed via a polymer quantum approach to the Universe scale factor and the proper classical limit is then recovered, in agreement with a preinflationary state of the Universe. Since the dust energy density is redshifted by the Universe deSitter phase and the cosmological constant does not enter the ground state eigenvalue, we get a late-time cosmology, compatible with the present observations, endowed with a turning point in the far future.
Quantum Mechanics, Gravity, and the Multiverse
Yasunori Nomura
2012-07-30T23:59:59.000Z
The discovery of accelerating expansion of the universe has led us to take the dramatic view that our universe may be one of the many universes in which low energy physical laws take different forms: the multiverse. I explain why/how this view is supported both observationally and theoretically, especially by string theory and eternal inflation. I then describe how quantum mechanics plays a crucial role in understanding the multiverse, even at the largest distance scales. The resulting picture leads to a revolutionary change of our view of spacetime and gravity, and completely unifies the paradigm of the eternally inflating multiverse with the many worlds interpretation of quantum mechanics. The picture also provides a solution to a long-standing problem in eternal inflation, called the measure problem, which I briefly describe.
Mixing lengths scaling in a gravity flow
Ecke, Robert E [Los Alamos National Laboratory; Rivera, Micheal [Los Alamos National Laboratory; Chen, Jun [Los Alamos National Laboratory; Ecke, Robert E [Los Alamos National Laboratory
2009-01-01T23:59:59.000Z
We present an experimental study of the mixing processes in a gravity current. The turbulent transport of momentum and buoyancy can be described in a very direct and compact form by a Prandtl mixing length model [1]: the turbulent vertical fluxes of momentum and buoyancy are found to scale quadraticatly with the vertical mean gradients of velocity and density. The scaling coefficient is the square of the mixing length, approximately constant over the mixing zone of the stratified shear layer. We show in this paper how, in different flow configurations, this length can be related to the shear length of the flow {radical}({var_epsilon}/{partial_derivative}{sub z}u{sup 3}).
Kinetic Gravity Braiding and axion inflation
Debaprasad Maity
2013-03-11T23:59:59.000Z
We constructed a new class of inflationary model with the higher derivative axion field which obeys constant shift symmetry. In the usual axion (natural) inflation, the axion decay constant is predicted to be in the super-Planckian regime which is believed to be incompatible with an effective field theory framework. With a novel mechanism originating from a higher derivative kinetic gravity braiding (KGB) of an axion field we found that there exist a huge parameter regime in our model where axion decay constant could be naturally sub-Planckian. Thanks to the KGB which effectively reduces the Planck constant. This effectively reduced Planck scale provides us the mechanism of further lowering down the speed of an axion field rolling down its potential without introducing super-Planckian axion decay constant. We also find that with that wide range of parameter values, our model induces almost scale invariant power spectrum as observed in CMB experiments.
A length operator for canonical quantum gravity
T. Thiemann
1996-06-29T23:59:59.000Z
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.
Bi-metric Gravity and "Dark Matter"
I. T. Drummond
2000-08-18T23:59:59.000Z
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.
Black Hole Thermodynamics in Modified Gravity
Jonas R. Mureika; John W. Moffat; Mir Faizal
2015-03-03T23:59:59.000Z
We analyze the thermodynamics of a non-rotating and rotating black hole in a modified theory of gravity that includes scalar and vector modifications to general relativity, which results in a modified gravitational constant $G = G_N(1+\\alpha)$ and a new gravitational charge $Q = \\sqrt{\\alpha G_N}M$. The influence of the parameter $\\alpha$ alters the non-rotating black hole's lifetime, temperature and entropy profiles from the standard Schwarzschild case. The thermodynamics of a rotating black hole is analyzed and it is shown to possess stable, cold remnants. The thermodynamic properties of a vacuum solution regular at $r=0$ are investigated and the solution without a horizon called a "gray hole" is not expected to possess an information loss problem.
Solar system tests of Ho?ava-Lifshitz gravity
Tiberiu Harko; Zoltan Kovács; Francisco S. N. Lobo
2010-10-28T23:59:59.000Z
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.
Goedel-type universes in f(R) gravity
Reboucas, M. J. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro-RJ (Brazil); Santos, J. [Universidade Federal do Rio G. do Norte, Departamento de Fisica, 59072-970 Natal-RN (Brazil)
2009-09-15T23:59:59.000Z
The f(R) gravity theories provide an alternative way to explain the current cosmic acceleration without a dark energy matter component. If gravity is governed by a f(R) theory, a number of issues should be reexamined in this framework, including the violation of causality problem on nonlocal scale. We examine the question as to whether the f(R) gravity theories permit space-times in which the causality is violated. We show that the field equations of these f(R) gravity theories do not exclude solutions with breakdown of causality for a physically well-motivated perfect-fluid matter content. We demonstrate that every perfect-fluid Goedel-type solution of a generic f(R) gravity satisfying the condition df/dR>0 is necessarily isometric to the Goedel geometry, and therefore presents violation of causality. This result extends a theorem on Goedel-type models, which has been established in the context of general relativity. We also derive an expression for the critical radius r{sub c} (beyond which the causality is violated) for an arbitrary f(R) theory, making apparent that the violation of causality depends on both the f(R) gravity theory and the matter content. As an illustration, we concretely take a recent f(R) gravity theory that is free from singularities of the Ricci scalar and is cosmologically viable, and show that this theory accommodates noncausal as well as causal Goedel-type solutions.
The dynamics of metric-affine gravity
Vitagliano, Vincenzo, E-mail: vitaglia@sissa.it [SISSA-International School for Advanced Studies, Via Bonomea 265, 34136 Trieste (Italy); INFN, Sez. di Trieste, Via Valerio 2, 34127 Trieste (Italy); Sotiriou, Thomas P., E-mail: T.Sotiriou@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom); Liberati, Stefano, E-mail: liberati@sissa.it [SISSA-International School for Advanced Studies, Via Bonomea 265, 34136 Trieste (Italy); INFN, Sez. di Trieste, Via Valerio 2, 34127 Trieste (Italy)
2011-05-15T23:59:59.000Z
Highlights: > The role and the dynamics of the connection in metric-affine theories is explored. > The most general second order action does not lead to a dynamical connection. > Including higher order invariants excites new degrees of freedom in the connection. > f(R) actions are also discussed and shown to be a non- representative class. - Abstract: Metric-affine theories of gravity provide an interesting alternative to general relativity: in such an approach, the metric and the affine (not necessarily symmetric) connection are independent quantities. Furthermore, the action should include covariant derivatives of the matter fields, with the covariant derivative naturally defined using the independent connection. As a result, in metric-affine theories a direct coupling involving matter and connection is also present. The role and the dynamics of the connection in such theories is explored. We employ power counting in order to construct the action and search for the minimal requirements it should satisfy for the connection to be dynamical. We find that for the most general action containing lower order invariants of the curvature and the torsion the independent connection does not carry any dynamics. It actually reduces to the role of an auxiliary field and can be completely eliminated algebraically in favour of the metric and the matter field, introducing extra interactions with respect to general relativity. However, we also show that including higher order terms in the action radically changes this picture and excites new degrees of freedom in the connection, making it (or parts of it) dynamical. Constructing actions that constitute exceptions to this rule requires significant fine tuned and/or extra a priori constraints on the connection. We also consider f(R) actions as a particular example in order to show that they constitute a distinct class of metric-affine theories with special properties, and as such they cannot be used as representative toy theories to study the properties of metric-affine gravity.
Particles on a Circle in Canonical Lineal Gravity
R. B. Mann
2001-05-02T23:59:59.000Z
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.
Emergent noncommutative gravity from a consistent deformation of gauge theory
Cortese, Ignacio; Garcia, J Antonio [Departamento de Fisica de Altas Energias, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, Mexico D. F. 04510 (Mexico)
2010-05-15T23:59:59.000Z
Starting from a standard noncommutative gauge theory and using the Seiberg-Witten map, we propose a new version of a noncommutative gravity. We use consistent deformation theory starting from a free gauge action and gauging a killing symmetry of the background metric to construct a deformation of the gauge theory that we can relate with gravity. The result of this consistent deformation of the gauge theory is nonpolynomial in A{sub {mu}.} From here we can construct a version of noncommutative gravity that is simpler than previous attempts. Our proposal is consistent and is not plagued with the problems of other approaches like twist symmetries or gauging other groups.
Flat space (higher spin) gravity with chemical potentials
Michael Gary; Daniel Grumiller; Max Riegler; Jan Rosseel
2014-11-24T23:59:59.000Z
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.
Emergent gravity/Non-linear U(1) gauge theory correspondence
Supriya Kar; K. Priyabrat Pandey; Abhishek K. Singh; Sunita Singh
2010-02-21T23:59:59.000Z
Kaluza-Klein gravity is revisted, with renewed interest, in a type IIB string theory on $S^1\\times K3$. The irreducible curvature tensors are worked out in the, T-dual, emergent gravity in 4D to yield a non-linear U(1) gauge theory. Interestingly, the T-duality may be seen to describe an open/closed string duality at a self-dual string coupling. The obtained deformation in $AdS_5$ black hole is analyzed to introduce the notion of temperature in the emergent gravity underlying the recent idea of entropic force.
Tsuchiya, Tomoko
2011-01-01T23:59:59.000Z
Justice: Americanization of Japanese War Crimes at the Endof the Post-Cold War. ” Journal of Asian American Studies256. Berry, Nicholas O. War and the Red Cross: The Unspoken
Hendi, Seyed Hossein; Panah, Behzad Eslam
2015-01-01T23:59:59.000Z
In this paper, we are considering two first order corrections to both gravity and gauge sides of the Einstein-Maxwell gravity: Gauss-Bonnet gravity and quadratic Maxwell invariant as corrections. We obtain horizonless magnetic solutions by implying a metric which representing a topological defect. We analyze the geometric properties of the solutions and investigate the effects of both corrections, and find that these solutions may be interpreted as the magnetic branes. We study the singularity condition and find a nonsingular spacetime with a conical geometry. We also investigate the effects of different parameters on deficit angle of spacetime near the origin.
Light deflection in Weyl gravity: critical distances for photon paths
S. Pireaux
2004-03-16T23:59:59.000Z
The Weyl gravity appears to be a very peculiar theory. The contribution of the Weyl linear parameter to the effective geodesic potential is opposite for massive and nonmassive geodesics. However, photon geodesics do not depend on the unknown conformal factor, unlike massive geodesics. Hence light deflection offers an interesting test of the Weyl theory. In order to investigate light deflection in the setting of Weyl gravity, we first distinguish between a weak field and a strong field approximation. Indeed, the Weyl gravity does not turn off asymptotically and becomes even stronger at larger distances. We then take full advantage of the conformal invariance of the photon effective potential to provide the key radial distances in Weyl gravity. According to those, we analyze the weak and strong field regime for light deflection. We further show some amazing features of the Weyl theory in the strong regime.
Ground Gravity Survey At Neal Hot Springs Geothermal Area (U...
Hot Springs. Data from these surveys will be integrated with older data from Chevron Minerals 1979 drill hole. Notes The gravity survey covered an area of approximately 34 km2...
Regional Gravity Survey of the Northern Great Salt Lake Desert...
Northern Great Salt Lake Desert and Adjacent Areas in Utah, Nevada, and Idaho Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: Regional Gravity...
An alternative derivation of the Minimal massive 3D gravity
Ahmet Baykal
2014-12-23T23:59:59.000Z
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.
Application Of Gravity And Deep Dipole Geoelectrics In The Volcanic...
Of Mt Etna (Sicily) Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: Application Of Gravity And Deep Dipole Geoelectrics In The Volcanic Area Of...
Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Lay, Erin H.; Shao, Xuan -Min; Kendrick, Alexander K.; Carrano, Charles S.
2015-07-30T23:59:59.000Z
Acoustic waves with periods of 2–4 min and gravity waves with periods of 6–16 min have been detected at ionospheric heights (25–350 km) using GPS total electron content measurements. The area disturbed by these waves and the wave amplitudes have been associated with underlying thunderstorm activity. A statistical study comparing Next Generation Weather Radar thunderstorm measurements with ionospheric acoustic and gravity waves in the midlatitude U.S. Great Plains region was performed for the time period of May–July 2005. An increase of ionospheric acoustic wave disturbed area and amplitude is primarily associated with large thunderstorms (mesoscale convective systems). Ionospheric gravity wavemore »disturbed area and amplitude scale with thunderstorm activity, with even small storms (i.e., individual storm cells) producing an increase of gravity waves.« less
Sudarshan Ananth; Mahendra Mali
2015-04-11T23:59:59.000Z
We derive a closed form expression for the light-cone Lagrangian describing pure gravity on a four-dimensional de Sitter background. We provide a perturbative expansion, of this Lagrangian, to cubic order in the fields.
Mixed convection and heat management in the Mars gravity biosatellite
Marsh, Jesse B. (Jesse Benjamin)
2007-01-01T23:59:59.000Z
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 ...
Ground Gravity Survey At Dixie Valley Geothermal Area (Iovenitti...
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...
The Basics of Water Waves Theory for Analogue Gravity
Germain Rousseaux
2012-03-14T23:59:59.000Z
This chapter gives an introduction to the connection between the physics of water waves and analogue gravity. Only a basic knowledge of fluid mechanics is assumed as a prerequisite.
Central American geologic map project
Dengo, G.
1986-07-01T23:59:59.000Z
During the Northeast Quadrant Panel meeting of the Circum-Pacific Map Project held in Mexico City, February 1985, Central American panel members proposed and adopted plans for compiling a geologic map of Central America, probably at a scale of 1:500,000. A local group with participants from each country was organized and coordinated by Rolando Castillo, director, Central American School of Geology, University of Costa Rica, for the geologic aspects, and Fernando Rudin, director, Geographic Institute of Costa Rica, for the topographic base. In 1956, the US Geological Survey published a geologic map of the region at a scale of 1:1 million. Subsequent topographic and geologic mapping projects have provided a large amount of new data. The entire area is now covered by topographic maps at a scale of 1:50,000, and these maps have been used in several countries as a base for geologic mapping. Another regional map, the Metallogenic Map of Central America (scale = 1:2 million), was published in 1969 by the Central American Research Institute for Industry (ICAITI) with a generalized but updated geologic base map. Between 1969 and 1980, maps for each country were published by local institutions: Guatemala-Belize at 1:500,000, Honduras at 1:500,000, El Salvador at 1:100,000, Nicaragua at 1:1 million, Costa Rica at 1:200,000, and Panama at 1:1 million. This information, in addition to that of newly mapped areas, served as the base for the Central American part of the Geologic-Tectonic Map of the Caribbean Region (scale = 1:2.5 million), published by the US Geological Survey in 1980, and also fro the Northeast Quadrant Maps of the Circum-Pacific Region. The new project also involves bathymetric and geologic mapping of the Pacific and Caribbean margins of the Central American Isthmus. A substantial amount of new information of the Middle America Trench has been acquired through DSDP Legs 67 and 84.
American Valve: Proposed Penalty (2010-CW-1411)
Broader source: Energy.gov [DOE]
DOE alleged in a Notice of Proposed Civil Penalty that American Valve, Inc. failed to certify a variety of showerheads as compliant with the applicable water conservation standards.
Americans with Disabilities Act Signed (1990)
Broader source: Energy.gov [DOE]
The Americans with Disabilities Act of 1990 (ADA) prohibits discrimination and ensures equal opportunity for persons with disabilities in employment, State and local government services, public...
Sandia National Laboratories: American Institute of Aeronautics...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Institute of Aeronautics and Astronautics Two Sandia Leaders Elected American Association for the Advancement of Science Fellows On December 15, 2014, in Climate, Energy,...
The Smithsonian American Art Museum GATEWAY Demonstration
Broader source: Energy.gov [DOE]
View the video about using LEDs in a GATEWAY demonstration at the Smithsonian American Art Museum in Washington, DC, including an interview with lighting designer Scott Rosenfeld.
New American Home 2011, Orlando, Florida (Brochure)
Not Available
2010-12-01T23:59:59.000Z
This brochure details the New American Home 2011, which demonstrates the use of innovative building materials, cutting-edge design, and the latest construction techniques.
North American Renewables Registry (Multiple States)
Broader source: Energy.gov [DOE]
The North American Renewables Registry (NAR) provides a Web-based platform trusted to create, track, and manage renewable energy certificate (REC) origination for clean generation facilities and...
North American Electric Reliability Corporation (NERC): Reliability...
Office of Environmental Management (EM)
(NERC): Reliability Considerations from the Integration of Smart Grid North American Electric Reliability Corporation (NERC): Reliability Considerations from the Integration of...
American Energy and Manufacturing Competitiveness Summit
Broader source: Energy.gov [DOE]
The American Energy and Manufacturing Competitiveness Summit will bring together leaders and perspectives from industry, government, academia, national laboratories, labor, and policy organizations...
Building America Research for the American Home
Broader source: Energy.gov [DOE]
The U.S. Department of Energy's (DOE) Building America program is helping to engineer American homes for better energy performance, durability, quality, affordability, and comfort.
Entropy and Area of Black Holes in Loop Quantum Gravity
I. B. Khriplovich
2002-03-31T23:59:59.000Z
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.
Gravity Control Propulsion: Towards a General Relativistic Approach
O. Bertolami; F. G. Pedro
2006-10-16T23:59:59.000Z
Evaluation of gravity control concepts should be examined with respect to currently known physical theories. In this work we study the hypothetical conversion of gravitational potential energy into kinetic energy using the formalism of general relativity. We show that the energy involved in the process greatly exceeds the Newtonian estimate, given the nature of general relativity. We conclude that the impact of any gravity manipulation for propulsion greatly depends fundamentally on its exact definition.
A Hopf Algebra Structure in Self-dual Gravity
Hugo Garcia-Compean; Laura E. Morales; Jerzy F. Plebanski
1996-01-20T23:59:59.000Z
The two-dimensional non-linear sigma model approach to Self-dual Yang-Mills theory and to Self-dual gravity given by Q-Han Park is an example of the deep interplay between two and four dimensional physics. In particular, Husain's two-dimensional chiral model approach to Self-dual gravity is studied. We show that the infinite hierarchy of conservation laws associated to the Husain model carries implicitly a hidden infinite Hopf algebra structure.
Gravity-free hydraulic jumps and metal femtocups
Rama Govindarajan; Manikandan Mathur; Ratul DasGupta; N. R. Selvi; Neena Susan John; G. U. Kulkarni
2006-10-03T23:59:59.000Z
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.
J. W. Maluf
2003-04-01T23:59:59.000Z
We show that the coupling of a Dirac spinor field with the gravitational field in the teleparallel equivalent of general relativity is consistent. For an arbitrary SO(3,1) connection there are two possibilities for the coupling of the spinor field with the gravitational field. The problems of consistency raised by Y. N. Obukhov and J. G. Pereira in the paper {\\it Metric-affine approach to teleparallel gravity} [gr-qc/0212080] take place only in the framework of one particular coupling. By adopting an alternative coupling the consistency problem disappears.
Energy Efficiency Improvement and Cost Saving Oportunities for the Concrete Industry
Kermeli, Katerina
2013-01-01T23:59:59.000Z
ACI 306 for Cold Weather Concreting and the guidelines in the StandardACI American Concrete Institute ASD Adjustable-speed drive ASTM American Society for StandardsACI 306R-2. American Society for Testing and Materials (ASTM) C94. Standard
Chang, Tzu-Fen
2012-02-14T23:59:59.000Z
with the dominant culture to show similar desires of being autonomous as European-American adolescents. However, Chinese-American mothers adopted more authoritarian, conservative, and inflexible parenting styles than European-American mothers. With regard...
Roylance, David
Proceedings of the 2004 American Society for Engineering Education Annual Conference & Exposition between the two institutions. #12;Proceedings of the 2004 American Society for Engineering Education Annual Conference & Exposition, Copyright © 2004, American Society for Engineering Education
Gravity stabilized thermal miscible displacement process
Vogel, J.V.
1987-10-06T23:59:59.000Z
A method is described of recovering viscous hydrocarbons from a subterranean reservoir. The reservoir is penetrated by at least one injection well and one production well. The injection well is in fluid communication with the upper portion of the reservoir and the production well is in fluid communication with the lower portion of the reservoir. The injection well and the production well defines a fluid flow path therebetween. The method comprises the steps of: (a) injecting a steam-solvent vapor mixture into the upper portion of the reservoir through the injection well. The steam-solvent vapor mixture is undersaturated in solvent and saturated with steam; (b) reducing the viscosity of the hydrocarbons by heat released upon condensation of the steam-solvent vapor mixture and reducing the viscosity of the hydrocarbons further upon condensation of solvent vapors. The condensed solvent vapors goes into solution with the hydrocarbons; and (c) collecting a mixture of hydrocarbons and solvent accumulated at the bottom of the production well substantially entirely under the force of gravity.
Quantization of neutron in Earth's gravity
Pulak Ranjan Giri
2007-08-22T23:59:59.000Z
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.
The local potential approximation in quantum gravity
Dario Benedetti; Francesco Caravelli
2012-10-09T23:59:59.000Z
Within the context of the functional renormalization group flow of gravity, we suggest that a generic f(R) ansatz (i.e. not truncated to any specific form, polynomial or not) for the effective action plays a role analogous to the local potential approximation (LPA) in scalar field theory. In the same spirit of the LPA, we derive and study an ordinary differential equation for f(R) to be satisfied by a fixed point of the renormalization group flow. As a first step in trying to assess the existence of global solutions (i.e. true fixed point) for such equation, we investigate here the properties of its solutions by a comparison of various series expansions and numerical integrations. In particular, we study the analyticity conditions required because of the presence of fixed singularities in the equation, and we develop an expansion of the solutions for large R up to order N=29. Studying the convergence of the fixed points of the truncated solutions with respect to N, we find a characteristic pattern for the location of the fixed points in the complex plane, with one point stemming out for its stability. Finally, we establish that if a non-Gaussian fixed point exists within the full f(R) approximation, it corresponds to an R^2 theory.
Scalar-tensor gravity and conformal continuations
Kirill A. Bronnikov
2002-03-30T23:59:59.000Z
Global properties of vacuum static, spherically symmetric configurations are studied in a general class of scalar-tensor theories (STT) of gravity in various dimensions. The conformal mapping between the Jordan and Einstein frames is used as a tool. Necessary and sufficient conditions are found for the existence of solutions admitting a conformal continuation (CC). The latter means that a singularity in the Einstein-frame manifold maps to a regular surface S_(trans) in the Jordan frame, and the solution is then continued beyond this surface. S_(trans) can be an ordinary regular sphere or a horizon. In the second case, S_(trans) proves to connect two epochs of a Kantowski-Sachs type cosmology. It is shown that, in an arbitrary STT, with arbitrary potential functions $U(\\phi)$, the list of possible types of causal structures of vacuum space-times is the same as in general relativity with a cosmological constant. This is true even for conformally continued solutions. It is found that when S_(trans) is an ordinary sphere, one of the generic structures appearing as a result of CC is a traversable wormhole. Two explicit examples are presented: a known solution illustrating the emergence of singularities and wormholes, and a nonsingular 3-dimensional model with an infinite sequence of CCs.
Scale-invariant gravity: Spacetime recovered
Bryan Kelleher
2004-07-28T23:59:59.000Z
The configuration space of general relativity is superspace - the space of all Riemannian 3-metrics modulo diffeomorphisms. However, it has been argued that the configuration space for gravity should be conformal superspace - the space of all Riemannian 3-metrics modulo diffeomorphisms and conformal transformations. Recently a manifestly 3-dimensional theory was constructed with conformal superspace as the configuration space. Here a fully 4-dimensional action is constructed so as to be invariant under conformal transformations of the 4-metric using general relativity as a guide. This action is then decomposed to a (3+1)-dimensional form and from this to its Jacobi form. The surprising thing is that the new theory turns out to be precisely the original 3-dimensional theory. The physical data is identified and used to find the physical representation of the theory. In this representation the theory is extremely similar to general relativity. The clarity of the 4-dimensional picture should prove very useful for comparing the theory with those aspects of general relativity which are usually treated in the 4-dimensional framework.
Testing Gravity with Cold-Atom Interferometers
G. W. Biedermann; X. Wu; L. Deslauriers; S. Roy; C. Mahadeswaraswamy; M. A. Kasevich
2014-12-10T23:59:59.000Z
We present a horizontal gravity gradiometer atom interferometer for precision gravitational tests. The horizontal configuration is superior for maximizing the inertial signal in the atom interferometer from a nearby proof mass. In our device, we have suppressed spurious noise associated with the horizonal configuration to achieve a differential acceleration sensitivity of 4.2$\\times10^{-9}g/\\sqrt{Hz}$ over a 70 cm baseline or 3.0$\\times10^{-9}g/\\sqrt{Hz}$ inferred per accelerometer. Using the performance of this instrument, we characterize the results of possible future gravitational tests. We complete a proof-of-concept measurement of the gravitational constant with a precision of 3$\\times10^{-4}$ that is competitive with the present limit of 1.2$\\times10^{-4}$ using other techniques. From this measurement, we provide a statistical constraint on a Yukawa-type fifth force at 8$\\times$10$^{-3}$ near the poorly known length scale of 10 cm. Limits approaching 10$^{-5}$ appear feasible. We discuss improvements that can enable uncertainties falling well below 10$^{-5}$ for both experiments.
Non-Singular Cosmology in Modified Gravity
J. W. Moffat
2007-10-24T23:59:59.000Z
A non-singular cosmology is derived in modified gravity (MOG) with a varying gravitational coupling strength $G(t)=G_N\\xi(t)$. Assuming that the curvature $k$, the cosmological constant $\\Lambda$ and $\\rho$ vanish at $t=0$, we obtain a non-singular universe with a negative pressure, $p_G < 0$. Quantum fluctuations at $t\\sim 0$ produce creation of pairs of particles from the vacuum explaining the origin of matter. The universe expands for $t\\to \\infty$ according to the standard radiation and matter dominated solutions. The arrow of time reverses at $t=0$ always pointing in the direction of increasing entropy ${\\cal S}$ and the entropy is at a minimum value at $t=0$, solving the conundrum of the Second Law of Thermodynamics. The Hubble radius $H^{-1}(t)$ is infinite at $t=0$ removing the curvature and particle horizons. The negative pressure $p_G$ generated by the scalar field $\\xi$ at $t\\sim 0$ can produce quantum spontaneous creation of particles explaining the origin of matter and radiation.
American Gas Association Memorandum Summarizing Ex Parte Communication...
Memorandum Summarizing Ex Parte Communication American Gas Association Memorandum Summarizing Ex Parte Communication On October 9, 2014, a workshop was hosted by the American Gas...
North American SynchroPhasor Initiative (NASPI) Technical Report...
Broader source: Energy.gov (indexed) [DOE]
visit the Transmission Reliability page. North American SynchroPhasor Initiative (NASPI) Technical Report - Phasor Tools Visualization More Documents & Publications North American...
North American SynchroPhasor Initiative (NASPI) Technical Report...
Broader source: Energy.gov (indexed) [DOE]
This technical report was developed in October, 2013 by members of the North American SynchroPhasor Initiative, a collaboration between the North American electric industry...
Taking the cure: Control and compliance in American medicine
Gosland, Melissa S
1993-01-01T23:59:59.000Z
and compliance in American medicine by Melissa Susan Goslandand compliance in American medicine ©1993 by Melissa Susancentury, however, that medicine began to consolidate its
Energy Department Authorizes American LNG Marketing LLC's Application...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Authorizes American LNG Marketing LLC's Application to Export Liquefied Natural Gas Energy Department Authorizes American LNG Marketing LLC's Application to Export Liquefied...
Energy Secretary Moniz Will Host North American Energy Ministers...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
highlight three key areas, including: 1) North American data collaboration, 2) Mexico's energy reform and its implications for the North American energy sector, and 3) creating a...
American Energy Data Challenge Hackathons - "Apps For Energy...
American Energy Data Challenge Hackathons - "Apps For Energy": Turning Energy Data into Working Apps in 24 Hours American Energy Data Challenge Hackathons - "Apps For Energy":...
Energy Department Selects Five Native American Communities to...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Five Native American Communities to Receive Technical Assistance for Tribal Renewable Energy Project Development Energy Department Selects Five Native American Communities to...
Diesel Engine Strategy & North American Market Challenges, Technology...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Strategy & North American Market Challenges, Technology and Growth Diesel Engine Strategy & North American Market Challenges, Technology and Growth Presentation given at the 2007...
North American Energy Ministers Take Further Action on Energy...
Office of Environmental Management (EM)
North American Energy Ministers Take Further Action on Energy Security and the Environment North American Energy Ministers Take Further Action on Energy Security and the...
DOE Announces Cooperative Agreement with USEC for American Centrifuge...
Cooperative Agreement with USEC for American Centrifuge Demonstration Project DOE Announces Cooperative Agreement with USEC for American Centrifuge Demonstration Project March 23,...
American Recovery and Reinvestment Act
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), 2002; Level:5 TablesExports(Journal Article)41cloth Documentation DataDepartment of EnergyOn-Farm Biofuelin HawaiiNatural Gasof Energy TribalNationalAmerican
Russell, Timothy Dale
2013-01-01T23:59:59.000Z
American Rebel in the Philippine, 1899-1901. ” The PacificSpanish-American War and Philippine Insurrection: Militaryofficers serving in the Philippines), acknowledged that the
Al-Juhani, Abdulhadi A.
Proceedings of the 2005 American Society for Engineering Education Annual Conference & Exposition on paper #12;Proceedings of the 2005 American Society for Engineering Education Annual Conference
ACCEPTABLE HUMANITIES (HU) COURSES * African American Studies
American Literature CAS AA 215 Arts of Africa and its Diaspora American & New England Studies CAS AM 200 and the Art of Film History of Art and Architecture All 100-, 200-, and 300-level CAS AH lecture courses offered in the History of Art & Architecture Department Modern Languages and Comparative Literature CAS LC
The North American Forest Sector Outlook Study
of the United Nations United Nations Economic Commission for Europe #12;#12;The North American Forest Sector Commission for Europe GENEVA TIMBER AND FOREST STUDY PAPER 29 #12;The North American Forest Sector Outlook for packaging and miscellaneous uses will continue to enjoy strong global demand. Keywords Bioenergy, biomass
American Cooler Technologies: Order (2013-CE-5305)
Broader source: Energy.gov [DOE]
DOE ordered American Cooler Technologies to pay a $8,000 civil penalty after finding American Cooler Technologies had failed to certify that certain models of walk-in coolers or freezers (WICF) components comply with the applicable energy conservation standards.
AmericanSociety of Civil Engineers
AmericanSociety of Civil Engineers Civil Engineering Body of Knowledge for the 21st Century Preparing the Civil Engineer for the Future Second Edition Prepared by the Body of Knowledge Committee Engineers--Registered in U.S. Patent and Trademark Office. American Society of Civil Engineers 1801
David Rettner, PE American Engineering Testing, Inc
Minnesota, University of
management ! Long range planning/budgeting ! Asset management ! Huge research potential! #12;Tools within. American Engineering Testing, Inc April 27, 2010 #12;Project Overview !! Funded and Managed by State Aid !! Project Advisors: MCEA 10-ton Committee !! Consultant: ·! Braun Intertec ·! American Engineering Testing
Matter Bounce Loop Quantum Cosmology from $F(R)$ Gravity
S. D. Odintsov; V. K. Oikonomou
2014-12-04T23:59:59.000Z
Using the reconstruction method, we investigate which $F(R)$ theories, with or without the presence of matter fluids, can produce the matter bounce scenario of holonomy corrected Loop Quantum Cosmology. We focus our study in two limits of the cosmic time, the large cosmic time limit and the small cosmic time limit. For the former, we found that, in the presence of non-interacting and non-relativistic matter, the $F(R)$ gravity that reproduces the late time limit of the matter bounce solution is actually the Einstein-Hilbert gravity plus a power law term. In the early time limit, since it corresponds to large spacetime curvatures, assuming that the Jordan frame is described by a general metric that when it is conformally transformed to the Einstein frame, produces an accelerating Friedmann-Robertson-Walker metric, we found explicitly the scalar field dependence on time. After demonstrating that the solution in the Einstein frame is indeed accelerating, we calculate the spectral index derived from the Einstein frame scalar-tensor counterpart theory of the $F(R)$ theory and compare it with the Planck experiment data. In order to implement the resulting picture, we embed the $F(R)$ gravity explicitly in a Loop Quantum Cosmology framework by introducing holonomy corrections to the $F(R)$ gravity. In this way, the resulting inflation picture corresponding to the $F(R)$ gravity can be corrected in order it coincides to some extent with the current experimental data.
Unscreening modified gravity in the matter power spectrum
Lombriser, Lucas; Mead, Alexander
2015-01-01T23:59:59.000Z
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...
Horava-Lifshitz Gravity From Dynamical Newton-Cartan Geometry
Jelle Hartong; Niels A. Obers
2015-04-28T23:59:59.000Z
Recently it has been established that torsional Newton-Cartan (TNC) geometry is the appropriate geometrical framework to which non-relativistic field theories couple. We show that when these geometries are made dynamical they give rise to Horava-Lifshitz (HL) gravity. Projectable HL gravity corresponds to dynamical Newton-Cartan (NC) geometry without torsion and non-projectable HL gravity corresponds to dynamical NC geometry with twistless torsion (hypersurface orthogonal foliation). We build a precise dictionary relating all fields (including the scalar khronon), their transformations and other properties in both HL gravity and dynamical TNC geometry. We use TNC invariance to construct the effective action for dynamical twistless torsional Newton-Cartan geometries in 2+1 dimensions for dynamical exponent 1Thompson as coming from the Bargmann extension of the local Galilean algebra that acts on the tangent space to TNC geometries. We argue that TNC geometry, which is manifestly diffeomorphism covariant, is a natural geometrical framework underlying HL gravity and discuss some of its implications.
Unscreening modified gravity in the matter power spectrum
Lucas Lombriser; Fergus Simpson; Alexander Mead
2015-01-20T23:59:59.000Z
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.
First tsunami gravity wave detection in ionospheric radio occultation data
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Coïsson, Pierdavide; Lognonné, Philippe; Walwer, Damian; Rolland, Lucie M.
2015-05-09T23:59:59.000Z
After the 11 March 2011 earthquake and tsunami off the coast of Tohoku, the ionospheric signature of the displacements induced in the overlying atmosphere has been observed by ground stations in various regions of the Pacific Ocean. We analyze here the data of radio occultation satellites, detecting the tsunami-driven gravity wave for the first time using a fully space-based ionospheric observation system. One satellite of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) recorded an occultation in the region above the tsunami 2.5 h after the earthquake. The ionosphere was sounded from top to bottom, thus providing themore »vertical structure of the gravity wave excited by the tsunami propagation, observed as oscillations of the ionospheric Total Electron Content (TEC). The observed vertical wavelength was about 50 km, with maximum amplitude exceeding 1 total electron content unit when the occultation reached 200 km height. We compared the observations with synthetic data obtained by summation of the tsunami-coupled gravity normal modes of the Earth/Ocean/atmosphere system, which models the associated motion of the ionosphere plasma. These results provide experimental constraints on the attenuation of the gravity wave with altitude due to atmosphere viscosity, improving the understanding of the propagation of tsunami-driven gravity waves in the upper atmosphere. They demonstrate that the amplitude of the tsunami can be estimated to within 20% by the recorded ionospheric data.« less
Grujicic, Mica
American Journal of Science and TechnologyAmerican Journal of Science and TechnologyAmerican Journal of Science and TechnologyAmerican Journal of Science and Technology 2014; 1(4): 168-181 Published online August 30, 2014 (http://www.aascit.org/journal/ajst) Keywords Injection Over-Molding, Polymer
Join us for the Third North American Congress
Barthelat, Francois
Oncology (ASPO) American Statistical Association-Epidemiology (ASA-EPI) Council of State and Territorial Society (AES) American Heart Association -Epidemiology Section(AHA-EPI) American Society for Preventive) International Society for Pharmacoepidemiology (ISPE) Mol Epi Group/American Association of Cancer Research (MEG
A Gradual Reawakening: Broadacre City and a New American Agrarianism
Wise, Ella
2013-01-01T23:59:59.000Z
Green Development, and Renewable Energy. 2nd ed. AmericanCritical Agrarianism. ” Renewable Agriculture and Food
Backreaction effects due to matter coupled higher derivative gravity
Lata Kh Joshi; P. Ramadevi
2014-11-28T23:59:59.000Z
AdS-hydrodynamics has proven to be a useful tool for obtaining transport coefficients observed in the collective flow of strongly coupled fluids like quark gluon plasma (QGP). Particularly, the ratio of shear viscosity to entropy density ${\\eta/ s}$ obtained from elliptic flow measurements can be matched with the computation done in the dual gravity theory. The experimentally observed temperature dependence of ${\\eta/ s}$ requires the study of scalar matter coupled AdS gravity including higher derivative curvature corrections. We obtain the backreaction to the metric for such a matter coupled AdS gravity in $D$-dimensional spacetime due to the higher derivative curvature corrections. Then, we present the backreaction corrections to shear-viscosity $\\eta$ and entropy density $s$.
Exotic Statistics for Ordinary Particles in Quantum Gravity
John Swain
2008-05-15T23:59:59.000Z
Objects exhibiting statistics other than the familiar Bose and Fermi ones are natural in theories with topologically nontrivial objects including geons, strings, and black holes. It is argued here from several viewpoints that the statistics of ordinary particles with which we are already familiar are likely to be modified due to quantum gravity effects. In particular, such modifications are argued to be present in loop quantum gravity and in any theory which represents spacetime in a fundamentally piecewise-linear fashion. The appearance of unusual statistics may be a generic feature (such as the deformed position-momentum uncertainty relations and the appearance of a fundamental length scale) which are to be expected in any theory of quantum gravity, and which could be testable.
Analogy between turbulence and quantum gravity: beyond Kolmogorov's 1941 theory
S. Succi
2011-11-14T23:59:59.000Z
Simple arguments based on the general properties of quantum fluctuations have been recently shown to imply that quantum fluctuations of spacetime obey the same scaling laws of the velocity fluctuations in a homogeneous incompressible turbulent flow, as described by Kolmogorov 1941 (K41) scaling theory. Less noted, however, is the fact that this analogy rules out the possibility of a fractal quantum spacetime, in contradiction with growing evidence in quantum gravity research. In this Note, we show that the notion of a fractal quantum spacetime can be restored by extending the analogy between turbulence and quantum gravity beyond the realm of K41 theory. In particular, it is shown that compatibility of a fractal quantum-space time with the recent Horava-Lifshitz scenario for quantum gravity, implies singular quantum wavefunctions. Finally, we propose an operational procedure, based on Extended Self-Similarity techniques, to inspect the (multi)-scaling properties of quantum gravitational fluctuations.
Nonlocal resonances in weak turbulence of gravity-capillary waves
Quentin Aubourg; Nicolas Mordant
2015-03-13T23:59:59.000Z
We report a laboratory investigation of weak turbulence of water surface waves in the gravity-capillary crossover. By using time-space resolved profilometry and a bicoherence analysis, we observe that the nonlinear processes involve 3-wave resonant interactions. By studying the solutions of the resonance conditions we show that the nonlinear interaction is dominantly 1D and involves collinear wave vectors. Furthermore taking into account the spectral widening due to weak nonlinearity explains that nonlocal interactions are possible between a gravity wave and high frequency capillary ones. We observe also that nonlinear 3-wave coupling is possible among gravity waves and we raise the question of the relevance of this mechanism for oceanic waves.
Compensational Gravity Fundamentals and an Application: The Cycling Universe
Vladimir S. Mashkevich
2010-04-16T23:59:59.000Z
Compensational gravity, which is regarded as a fundamental theory, is an advanced version of semiclassical gravity. It is a construction which extends the Einstein equation. Along with the energy-momentum tensor, the extended Einstein equation includes the compensation tensor, or compenson. The latter compensates for the energy-momentum tensor insufficiency, which consists in the discontinuity in time (due to quantum state reduction) and in space (due to sharp cutoff), as well as in an anomaly (nonrealistic state equation and nonzero divergence). The compenson is a primary object, for which equations are formulated. Specifically, purely dark objects may or may not exist. The dynamics of compensational gravity gives rise naturally to the cosmological constant, or dark energy and to dark matter: The compenson versus particle dark matter. On the basis of the dynamics, a cycling model of the closed universe is constructed.
Constraints on the quantum gravity scale from kappa - Minkowski spacetime
A. Borowiec; Kumar S. Gupta; S. Meljanac; A. Pachol
2010-11-18T23:59:59.000Z
We compare two versions of deformed dispersion relations (energy vs momenta and momenta vs energy) and the corresponding time delay up to the second order accuracy in the quantum gravity scale (deformation parameter). A general framework describing modified dispersion relations and time delay with respect to different noncommutative kappa -Minkowski spacetime realizations is firstly proposed here and it covers all the cases introduced in the literature. It is shown that some of the realizations provide certain bounds on quadratic corrections, i.e. on quantum gravity scale, but it is not excluded in our framework that quantum gravity scale is the Planck scale. We also show how the coefficients in the dispersion relations can be obtained through a multiparameter fit of the gamma ray burst (GRB) data.
Extended Theories of Gravity with Generalized Energy Conditions
José P. Mimoso; Francisco S. N. Lobo; Salvatore Capozziello
2014-12-20T23:59:59.000Z
We address the problem of the energy conditions in modified gravity taking into account the additional degrees of freedom related to scalar fields and curvature invariants. The latter are usually interpreted as generalized {\\it geometrical fluids} that differ in meaning with respect to the matter fluids generally considered as sources of the field equations. In extended gravity theories the curvature terms are encapsulated in a tensor $H^{ab}$ and a coupling $g(\\Psi^i)$ that can be recast as effective Einstein field equations, with corrections to the energy-momentum tensor of matter. The formal validity of standard energy inequalities does not assure basic requirements such as the attractive nature of gravity, so we argue that the energy conditions have to be considered in a wider sense.
Direct Detection of Gravity Waves from Neutron Stars
Redouane Al Fakir; William G. Unruh
2008-05-24T23:59:59.000Z
In light of the discovery of the first-ever double pulsar system, PSR J0737-3039, we re-examine an earlier proposal to directly detect gravity waves from neutron stars, which was predicated on a hypothetical system almost identical to the later discovered double pulsar. We re-derive the effect in more detail, and confirm the initial estimate--sometimes doubted in the literature--that it includes a 1/b dependence, where b is the impact parameter of a pulsar with respect to its foreground, gravity-wave emitting, neutron star companion. A coherent modulation in pulsar time-of-arrival measurements of 10 nano-sec/sec is possible. A one-year intermittent experiment on an instrument comparable to the SKA could thus detect the exceedingly faint gravity waves from individual neutron stars.
Asymptotic safety of gravity and the Higgs boson mass
Mikhail Shaposhnikov; Christof Wetterich
2010-01-12T23:59:59.000Z
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.
Superbounce and Loop Quantum Cosmology Ekpyrosis from Modified Gravity
V. K. Oikonomou
2015-04-07T23:59:59.000Z
As is known, in modified cosmological theories of gravity many of the cosmologies which could not be generated by standard Einstein gravity, can be consistently described by $F(R)$ theories. Using known reconstruction techniques, we investigate which $F(R)$ theories can lead to a Hubble parameter describing two types of cosmological bounces, the superbounce model, related to supergravity and non-supersymmetric models of contracting ekpyrosis and also the Loop Quantum Cosmology modified ekpyrotic model. Since our method is an approximate method, we investigate the problem at large and small curvatures. As we evince, both models yield power law reconstructed $F(R)$ gravities, with the most interesting new feature being that both lead to accelerating cosmologies, in the large curvature approximation. The mathematical properties of the some Friedmann-Robertson-Walker spacetimes $M$, that describe superbounce-like cosmologies are also pointed out, with regards to the group of curvature collineations $CC(M)$.
Static self-gravitating many-body systems in Einstein gravity
Lars Andersson; Berndt G. Schmidt
2009-05-08T23:59:59.000Z
We consider the problem of constructing static, elastic, many-body systems in Einstein gravity. The solutions constructed are deformations of static many-body configurations in Newtonian gravity. No symmetry assumptions are made.
The impact of gravity segregation on multiphase non-Darcy flow in hydraulically fractured gas wells
Dickins, Mark Ian
2008-10-10T23:59:59.000Z
and saturations in the fracture agrees well with reservoir simulation. Gravity segregation occurs in moderate-to-high conductivity fractures. Gravity segregation impacts effective fracture conductivity when gas and liquid are being produced at all water-gas ratios...
A Modified Gravity and its Consequences for the Solar System, Astrophysics and Cosmology
J. W. Moffat
2006-12-17T23:59:59.000Z
A relativistic modified gravity (MOG) theory leads to a self-consistent, stable gravity theory that can describe the solar system, galaxy and clusters of galaxies data and cosmology.
Mexican American city officials in Texas
Arriaga, Adrian Aron
1973-01-01T23:59:59.000Z
Science MEXICAN AMERICAN CITY OFFICIALS IN TEXAS A Thesis by ADRIAN ARON ARRIAGA Approved as to style and content by: Chairman of Committee Mem r Member August 1973 ABSTRACT Nex1can Amer1can City Offic1als 1n Texas. (August 1973) Adrian Aron.... 35 As Nex1can American veterans returned home, new ambitions started to form. The G. I. Bill provided needed educa- tion for Mexican Amer1cans who took the opportunity. 36 New self- confidence led Mexican Americans to establish a number of impor...
Negative mode problem in false vacuum decay with gravity
George Lavrelashvili
2000-04-08T23:59:59.000Z
There is a single negative mode in the spectrum of small perturbations about the tunneling solutions describing a metastable vacuum decay in flat spacetime. This mode is needed for consistent description of decay processes. When gravity is included the situation is more complicated. An approach based on elimination of scalar field perturbations shows no negative mode, whereas the recent approach based on elimination of gravitational perturbations indicates presence of a negative mode. In this contribution we analyse and compare the present approaches to the negative mode problem in false vacuum decay with gravity.
Consistent Evolution with Different Time-Slicings in Quantum Gravity
R. Cosgrove
1996-02-20T23:59:59.000Z
Rovelli's `` quantum mechanics without time'' motivates an intrinsically time-slicing independent picture of reduced phase space quantum gravity, which may be described as ``quantization after evolution''. Sufficient criteria for carrying out quantization after evolution are developed in terms of a general concept of the classical limit of quantum mechanics. If these criteria are satisfied then it is possible to have consistent unitary evolution of operators, with respect to an infinite parameter family of time-slicings (and probably all time-slicings), with the correct classical limit. The criteria are particularly amenable to study in (2+1)-dimensional gravity, where the reduced phase space is finite dimensional.
Dynamics of the Cosmological Apparent Horizon: Surface Gravity & Temperature
Alexis Helou
2015-02-14T23:59:59.000Z
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.
Irrotational-fluid cosmologies in fourth-order gravity
Amare Abebe; Maye Elmardi
2015-04-25T23:59:59.000Z
In this paper, we explore classes of irrotational-fluid cosmological models in the context of f(R)-gravity in an attempt to put some theoretical and mathematical restrictions on the form of the f(R) gravitational Lagrangian. In particular, we investigate the consistency of linearised dust models for shear-free cases as well as in the limiting cases when either the gravito-magnetic or gravito-elecric components of the Weyl tensor vanish. We also discuss the existence and consistency of classes of non-expanding irrotational spacetimes in f(R)-gravity.
Evidence for cenozoic rifting in Thailand from gravity modeling
Ohnstad, Tiffany A.
1990-01-01T23:59:59.000Z
at the teriiunation of a large NiVW-SSE trending strike-slip fault related to the extrusion of a. portion of Indochina away froni India, as it collided with Eurasia. . Rifting did not continue alotlg the trencl of the strike-slip fault zone; instead... gravity anomalies from the gndderl geoid heights, a two-diuieusional forur of Lap)&ace's equation in cartesian coordinates was?sed: d~g, , 'i3s =- g?(r3, , 'i)z(?~, 'oz) ? 8/c)y(clh/ dy)) wher'e 2 7 is the gravit'y anoulalv to bc dp'terminpcl, Ji? ls...
On the critical temperatures of superconductors: a quantum gravity approach
Andrea Gregori
2010-07-06T23:59:59.000Z
We consider superconductivity in the light of the quantum gravity theoretical framework introduced in [1]. In this framework, the degree of quantum delocalization depends on the geometry of the energy distribution along space. This results in a dependence of the critical temperature characterizing the transition to the superconducting phase on the complexity of the structure of a superconductor. We consider concrete examples, ranging from low to high temperature superconductors, and discuss how the critical temperature can be predicted once the quantum gravity effects are taken into account.
Time machines and traversable wormholes in modified theories of gravity
Francisco S. N. Lobo
2012-12-05T23:59:59.000Z
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.
Gravity Survey of the Carson Sink - Data and Maps
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Faulds, James E.
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.
Static Charged Black Hole Solutions in Horava-Lifshitz Gravity
Jin-Zhang Tang
2010-01-12T23:59:59.000Z
In the present work, we search static charged black hole solutions to Ho\\v{r}ava-Lifshitz gravity with or without projectability condition. We consider the most general form of action which electromagnetic field couples with Ho\\v{r}ava-Lifshitz gravity. With the projectability condition, we find dS-Reissner-Nordstrom black hole solution in Painlev\\'e-Gullstrand type coordinates in the IR region and a de-Sitter space-time solution in the UV region. Without the projectability condition, in the IR region, we find an especial static charged black hole solution.
SL(2,C) gravity on noncommutative space with Poisson structure
Miao Yangang; Zhang Shaojun [Department of Physics, Nankai University, Tianjin 300071 (China)
2010-10-15T23:59:59.000Z
The Einstein's gravity theory can be formulated as an SL(2,C) gauge theory in terms of spinor notations. In this paper, we consider a noncommutative space with the Poisson structure and construct an SL(2,C) formulation of gravity on such a space. Using the covariant coordinate technique, we build a gauge invariant action in which, according to the Seiberg-Witten map, the physical degrees of freedom are expressed in terms of their commutative counterparts up to the first order in noncommutative parameters.
Minimum length, extra dimensions, modified gravity and black hole remnants
Maziashvili, Michael, E-mail: maziashvili@gmail.com [Particle Physics and Cosmology Group, Ilia State University, 3/5 Cholokashvili Ave., Tbilisi 0162, Georgia (United States)
2013-03-01T23:59:59.000Z
We construct a Hilbert space representation of minimum-length deformed uncertainty relation in presence of extra dimensions. Following this construction, we study corrections to the gravitational potential (back reaction on gravity) with the use of correspondingly modified propagator in presence of two (spatial) extra dimensions. Interestingly enough, for r?0 the gravitational force approaches zero and the horizon for modified Schwarzschild-Tangherlini space-time disappears when the mass approaches quantum-gravity energy scale. This result points out to the existence of zero-temperature black hole remnants in ADD brane-world model.
Power-counting renormalizability of generalized Horava gravity
Visser, Matt
2009-01-01T23:59:59.000Z
In an earlier article [arXiv:0902.0590 [hep-th], Phys. Rev D80 (2009) 025011], I discussed the potential benefits of allowing Lorentz symmetry breaking in quantum field theories. In particular I discussed the perturbative power-counting finiteness of the normal-ordered :P(phi)^{z>=d}_{d+1}: scalar quantum field theories, and sketched the implications for Horava's model of quantum gravity. In the current rather brief addendum, I will tidy up some dangling issues and fill out some of the technical details of the argument indicating the power-counting renormalizability of a z>=d variant of Horava gravity in (d+1) dimensions.
Signatures of fractal clustering of aerosols advected under gravity
Rafael Dias Vilela; Tamás Tél; Alessandro P. S. de Moura; Celso Grebogi
2007-06-15T23:59:59.000Z
Aerosols under chaotic advection often approach a strange attractor. They move chaotically on this fractal set but, in the presence of gravity, they have a net vertical motion downwards. In practical situations, observational data may be available only at a given level, for example at the ground level. We uncover two fractal signatures of chaotic advection of aerosols under the action of gravity. Each one enables the computation of the fractal dimension $D_{0}$ of the strange attractor governing the advection dynamics from data obtained solely at a given level. We illustrate our theoretical findings with a numerical experiment and discuss their possible relevance to meteorology.
Dirac Fields in Loop Quantum Gravity and Big Bang Nucleosynthesis
Martin Bojowald; Rupam Das; Robert J. Scherrer
2008-03-19T23:59:59.000Z
Big Bang nucleosynthesis requires a fine balance between equations of state for photons and relativistic fermions. Several corrections to equation of state parameters arise from classical and quantum physics, which are derived here from a canonical perspective. In particular, loop quantum gravity allows one to compute quantum gravity corrections for Maxwell and Dirac fields. Although the classical actions are very different, quantum corrections to the equation of state are remarkably similar. To lowest order, these corrections take the form of an overall expansion-dependent multiplicative factor in the total density. We use these results, along with the predictions of Big Bang nucleosynthesis, to place bounds on these corrections.
3D gravity with dust: classical and quantum theory
Viqar Husain; Jonathan Ziprick
2015-06-02T23:59:59.000Z
We study the Einstein gravity and dust system in three spacetime dimensions as an example of a non-perturbative quantum gravity model with local degrees of freedom. We derive the Hamiltonian theory in the dust time gauge and show that it has a rich class of exact solutions. These include the Ba\\~nados-Teitelboim-Zanelli black hole, static solutions with naked singularities and travelling wave solutions with dynamical horizons. We give a complete quantization of the wave sector of the theory, including a definition of a self-adjoint spacetime metric operator. This operator is used to demonstrate the quantization of deficit angle and the fluctuation of dynamical horizons.
Ashtekar Formulation of 2+1 Gravity on a Torus
N. Manojlovic; A. Mikovic
1992-04-09T23:59:59.000Z
Pure (2+1)-dimensional Einstein gravity is analysed in the Ashtekar formulation, when the spatial manifold is a torus. We have found a set of globally defined observables, forming a closed algebra. This allowed us to solve the quantum constraints, and to show that the reduced phase space of the Ashtekar formulation is greater then the corresponding space of the Witten formulation. Furthermore, we have found a globally defined time variable which satisfies all the requiriments of an extrinsic time variable in quantum gravity.
Power-counting renormalizability of generalized Horava gravity
Matt Visser
2009-12-24T23:59:59.000Z
In an earlier article [arXiv:0902.0590 [hep-th], Phys. Rev D80 (2009) 025011], I discussed the potential benefits of allowing Lorentz symmetry breaking in quantum field theories. In particular I discussed the perturbative power-counting finiteness of the normal-ordered :P(phi)^{z>=d}_{d+1}: scalar quantum field theories, and sketched the implications for Horava's model of quantum gravity. In the current rather brief addendum, I will tidy up some dangling issues and fill out some of the technical details of the argument indicating the power-counting renormalizability of a z>=d variant of Horava gravity in (d+1) dimensions.
Viscoelastic Suppression of Gravity-Driven Counterflow Instability
Beiersdorfer, P; Layne, D; Magee, E W
2010-01-01T23:59:59.000Z
Attempts to achieve ``top kill'' of actively flowing oil wells by insertion of dense drilling ``muds'', i.e., slurries of dense minerals, from above will fail if the Kelvin-Helmholtz instability in the gravity-driven counterflow produces turbulence that breaks up the denser fluid into small droplets. Here we estimate the droplet size to be sub-mm for fast flows and suggest the addition of a shear-thickening polymer to suppress turbulence. Laboratory experiments show a progression from droplet formation to complete turbulence suppression at the relevant high velocities, illustrating rich new physics accessible by using a shear-thickening liquid in gravity driven counter-streaming flows.
Causality Constraint on Noncritical Einstein-Weyl Gravity
Fu-Wen Shu; Yungui Gong
2014-10-31T23:59:59.000Z
We explore, in the context of AdS/CFT correspondence, the causality constraints on the Noncritical Einstein-Weyl (NEW) gravity model in five dimensions. The scalar and shear channels are considered as small metric perturbations around an AdS black brane background. Our results show that causality analysis on the propagation of these two channels imposes a new bound on the coupling of the Weyl-squared terms in the NEW gravity. This new bound imposes more stringent restrictions than those of the tachyon-free condition, improving predictive power of the theory.
Classical and Quantum Aspects of 1+1 Gravity
T. Kloesch; P. Schaller; T. Strobl
1996-08-02T23:59:59.000Z
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.
Complete Classification of 1+1 Gravity Solutions
T. Kloesch; T. Strobl
1997-11-25T23:59:59.000Z
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.
Kolmogorov Algorithmic Complexity and its Probability Interpretation in Quantum Gravity
V. D. Dzhunushaliev
1997-04-16T23:59:59.000Z
The quantum gravity has great difficulties with application of the probability notion. In given article this problem is analyzed according to algorithmic viewpoint. According to A.N. Kolmogorov, the probability notion can be connected with algorithmic complexity of given object. The paper proposes an interpretation of quantum gravity, according to which an appearance of something corresponds to its Kolmogorov's algorithmic complexity. By this viewpoint the following questions are considered: the quantum transition with supplementary coordinates splitting off, the algorithmic complexity of the Schwarzschild black hole is estimated, the redefinition of the Feynman path integral, the quantum birth of the Euclidean Universe with the following changing of the metric signature.
Time Delay Predictions in a Modified Gravity Theory
J. W. Moffat
2006-06-01T23:59:59.000Z
The time delay effect for planets and spacecraft is obtained from a fully relativistic modified gravity theory including a fifth force skew symmetric field by fitting to the Pioneer 10/11 anomalous acceleration data. A possible detection of the predicted time delay corrections to general relativity for the outer planets and future spacecraft missions is considered. The time delay correction to GR predicted by the modified gravity is consistent with the observational limit of the Doppler tracking measurement reported by the Cassini spacecraft on its way to Saturn, and the correction increases to a value that could be measured for a spacecraft approaching Neptune and Pluto.
Thermodynamics on the apparent horizon in generalized gravity theories
Shao-Feng Wu; Bin Wang; Guo-Hong Yang
2008-01-17T23:59:59.000Z
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.
BTZ black hole from (3+1) gravity
M. Cataldo; S. del Campo; A. Garcia
2000-04-07T23:59:59.000Z
We propose an approach for constructing spatial slices of (3+1) spacetimes with cosmological constant but without a matter content, which yields (2+1) vacuum with $\\Lambda$ solutions. The reduction mechanism from (3+1) to (2+1) gravity is supported on a criterion in which the Weyl tensor components are required to vanish together with a dimensional reduction via an appropriate foliation. By using an adequate reduction mechanism from the Pleba\\'nski-Carter[A] solution in (3+1) gravity, the (2+1) BTZ solution can be obtained.
Monte Carlo simulations of 4d simplicial quantum gravity
B. Bruegmann; E. Marinari
1995-04-08T23:59:59.000Z
Dynamical triangulations of four-dimensional Euclidean quantum gravity give rise to an interesting, numerically accessible model of quantum gravity. We give a simple introduction to the model and discuss two particularly important issues. One is that contrary to recent claims there is strong analytical and numerical evidence for the existence of an exponential bound that makes the partition function well-defined. The other is that there may be an ambiguity in the choice of the measure of the discrete model which could even lead to the existence of different universality classes.
Ham, Arwen Eugene
2013-02-22T23:59:59.000Z
in partial fulfil/ment of the requirements of the UNIVERSITY UNDERGRADUATE RESEARCH FELLOWS April 2004 Major: Psychology CHASING THE ILLUSIVE AMERICAN DREAM: AN HISTORICAL ANALYSIS OF MEXICAN-AMERICAN EDUCATION, EMPLOYMENT, AND CULTURE A Senior Honors... Approved as to style and content by: s~= Sara Alpe (Fellows Advisor) April 2004 Major: Psychology ABSTRACT Chasing the Illusive American Dream: An Historical Analysis of Mexican-Atnerican Education, Employment, and Culture. (April 2004) Arwen...
Differences in Mexican-American and Anglo-American Women's Response to a Modified Clothing TAT.
Bathke, Carol Sander
1968-01-01T23:59:59.000Z
in the United States (1 1). It was theorized that be- cause the Anglo-American level of education generally was higher than that of the Mexican-Americans, the former would tend to take education for granted and thus would be less c~~gnizant of education...B-1076 September 1968 Differences in Mexican-American And Anglo-American Women's Responses To a Modified Clothing TAT TEXAS A&M UNIVERSITY TEXAS AGRICULTURAL EXPERIMENT STATION H. 0. Kunkel, Acting Director, College Station, Texas CONTENTS...
Efficient Models for the Evaluation and Estimation of the Gravity Field
Born, George
models. Problem Cubed-Sphere Gravity Model Designed for Fast Evaluation Orbit Propagation/FORMOSAT-3 4 #12;The spherical harmonic gravity model dominates force model execution time 0 10 20 30 40 50 60 Two-Body + Overhead Precession Nutation Gravity (36x36) Lunar-Solar Drag SRP Jacobian (36x36
Localized gravity/topography admittance and correlation spectra on Mars: Implications for
Simons, Mark
Localized gravity/topography admittance and correlation spectra on Mars: Implications for regional] From gravity and topography data collected by the Mars Global Surveyor spacecraft we calculate gravity/topography of an elastic/plastic shell. In regions of high topography on Mars (e.g., the Tharsis rise and associated shield
Gravity-Driven flow of evaporating thin liquid films over substrates with topography
Jimack, Peter
Gravity-Driven flow of evaporating thin liquid films over substrates with topography Gaskell, P. Abstract This paper considers gravity-driven flow of thin liquid films over substrates with topography of gravity-driven flow of thin liquid films over well defined topography, as indicated in Figure 1, in which
Sandwell, David T.
1 Gravity/Topography Transfer Function and Isostatic Geoid Anomalies (Copyright 2002, David T to develop a linear relationship between gravity and topography. This relationship can be used in a variety of ways. (1) If both the topography and gravity are measured over an area that is several times greater
An optimizing reduced order FDS for the tropical Pacific Ocean reduced gravity model
Aluffi, Paolo
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
Impact of boundary conditions on entrainment and transport in gravity currents
Duan, Jinqiao
Impact of boundary conditions on entrainment and transport in gravity currents Vena Pearl Bon on the entrainment and transport of gravity currents. The finding is that gravity currents under these two different difference occurs at medium temperature ranges. Entrainment and transport at high temperatures also show
Evolution of the contact network during tilting cycles of a granular pile under gravity
Staron, Lydie
Evolution of the contact network during tilting cycles of a granular pile under gravity S. Deboeuf of a granular pile undergoing quasi-static tilting cycles in the gravity field. The volumic deformation of granular piles during continuous load in the gravity field (Staron, Vilotte, & Radjai 2002). Far before
Wavelet denoising of gravity gradiometry data Julio Cesar S. O. Lyrio*
Wavelet denoising of gravity gradiometry data Julio Cesar S. O. Lyrio* Gravity and Magnetic an automatic 1D wavelet filtering technique, specially designed to process gravity gradiometry data. The method uses compactly supported orthonormal wavelets that selectively filter out localized high
Canonical quantization of a minisuperspace model for gravity using self-dual variables
T. Thiemann
1999-10-04T23:59:59.000Z
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.
Paris-Sud XI, Université de
Gravity wave turbulence revealed by horizontal vibrations of the container B. Issenmann and E: December 20, 2012) We experimentally study the role of the forcing on gravity-capillary wave turbulence that the frequency power-law exponent of the gravity wave spectrum depends on the forcing parameters. By horizontally
Lu, Yang
2005-01-01T23:59:59.000Z
1991). American public library service to the immigrantEquality: American Public Library Services with Minoritiesfor the American public library enterprise. Libraries,
New Central American Cinema (2001-2010)
Duró n, Hispano
2014-05-31T23:59:59.000Z
This dissertation explores New Central American Cinema, a film movement that emerged in Central America during the 2000s. It examines feature-length fictional films produced and released in Central America between 2001-2010. ...
Transforming the American Economy Through Innovation
Broader source: Energy.gov [DOE]
Secretary Chu joins Vice President Joe Biden as he details the role the Recovery Act has played in funding innovation that will help build a foundation for a more robust and competitive American...
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY
Lee, Kyu-Hwan J.
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY Volume 142, Number 7, July 2014, Pages 22912301.99.16.10. License or copyright restrictions may apply to redistribution; see http://www.ams
American Process—Alpena Biorefinery Lessons
Broader source: Energy.gov [DOE]
Breakout Session 1D—Building Market Confidence and Understanding I: Integrated Biorefinery (Lessons Learned and Best Practices) American Process—Alpena Biorefinery Lessons Theodora Retsina, Chief Executive Officer, America Process Inc.
EIS-0468: American Centrifuge Plant, Piketon, Ohio
Broader source: Energy.gov [DOE]
This EIS evaluates the environmental impacts of construction, operation, and decommissioning of the American Centrifuge Plant (ACP), located on DOE reservation in Piketon, Ohio. (DOE adopted this EIS issued by the Nuclear Regulatory Commission on 02/16/2011.)
American Evaluation Association Guiding Principles for Evaluators
None
2009-01-18T23:59:59.000Z
Five principles developed by American Evaluation Associ intended to guide professional practice of evaluators & to inform evaluation clients and the general public about principles they can expect to be upheld by professional evaluators.
American Wind Energy Association Offshore WINDPOWER Conference...
Office of Environmental Management (EM)
Offshore WINDPOWER Conference & Exhibition American Wind Energy Association Offshore WINDPOWER Conference & Exhibition October 7, 2014 9:00AM EDT to October 8, 2014 5:00PM EDT AWEA...
The Ecohydrology of South American Rivers
McClain, Michael
The Ecohydrology of South American Rivers and Wetlands edited by Michael E. McClain Department research integrating the physical processes of hydrology with the biological processes of ecology. Together
ORISE: College of American Pathologists renews accreditation...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
College of American Pathologists renews accreditation of ORISE beryllium laboratory Lab is one of only four in U.S. certified to test for sensitization to beryllium FOR IMMEDIATE...
American Power: Proposed Penalty (2010-CE-0911)
Broader source: Energy.gov [DOE]
DOE alleged in a Notice of Proposed Civil Penalty that American Power Solutions, Inc. failed to certify a general service fluorescent lamp as compliant with the applicable energy conservation standards.
Sentimental Poetry of the American Civil War
Trapp, Marjorie Jane
2010-01-01T23:59:59.000Z
Company, 1866. Devon, W. A. War Lyrics. New York: SinclairHickey, ed. Ballads of the War. New York: J. Robins, 1862.Eggleston, G. C, ed. American War Ballads and Lyrics. New
TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY
Edgar, Gerald
)0000-0 FRACTIONAL ITERATION OF SERIES AND TRANSSERIES G. A. EDGAR Abstract. We investigate; Secondary 41A60, 39B12, 30B10. c XXXX American Mathematical Society 1 #12;2 G. A. EDGAR Review
Structural determinants of Mexican American intermarriage
Anderson, Robert Niel
1992-01-01T23:59:59.000Z
STRUCTURAL DETERMINANTS OF MEXICAN AMERICAN INTERMARRIAGE A Thesis ROBERT NIEL ANDERSON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August... 1992 Major Subject: Sociology STRUCTURAL DETERMINANTS OF MEXICAN AMERICAN INTERMARRIAGE A Thesis ROBERT NIEL ANDERSON Approved as to style and content by: Rogelio Saenz (Chair of Committee) Mark A. Fossett (Member) Don E. Albrecht (Member...
American Energy and Manufacturing Competitiveness Summit
Broader source: Energy.gov [DOE]
The 2015 American Energy and Manufacturing Competitiveness Summit will be hosted September 15–16; this gathering of preeminent leaders from industry, academia, labor, the national laboratories, government, and media aims to increase American competitiveness in clean energy and manufacturing. Bioenergy Technologies Office Technology Manager Jay Fitzgerald will be representing the Office, and the Lawrence Berkeley National Lab will be exhibiting a special hands-on demonstration of the latest bioenergy equipment, models, and other research, development, and demonstration tools.
Quantum-Gravity Fluctuations and the Black-Hole Temperature
Hod, Shahar
2015-01-01T23:59:59.000Z
Bekenstein has put forward the idea that, in a quantum theory of gravity, a black hole should have a discrete energy spectrum with concomitant discrete line emission. The quantized black-hole radiation spectrum is expected to be very different from Hawking's semi-classical prediction of a thermal black-hole radiation spectrum. One naturally wonders: Is it possible to reconcile the {\\it discrete} quantum spectrum suggested by Bekenstein with the {\\it continuous} semi-classical spectrum suggested by Hawking ? In order to address this fundamental question, in this essay we shall consider the zero-point quantum-gravity fluctuations of the black-hole spacetime. In a quantum theory of gravity, these spacetime fluctuations are closely related to the characteristic gravitational resonances of the corresponding black-hole spacetime. Assuming that the energy of the black-hole radiation stems from these zero-point quantum-gravity fluctuations of the black-hole spacetime, we derive the effective temperature of the quanti...
Extra force in Kaluza-Klein gravity theory
W. B. Belayev
2007-06-18T23:59:59.000Z
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.
On the q-quantum gravity loop algebra
Seth Major
2008-02-19T23:59:59.000Z
A class of deformations of the q-quantum gravity loop algebra is shown to be incompatible with the combinatorics of Temperley-Lieb recoupling theory with deformation parameter at a root of unity. This incompatibility appears to extend to more general deformation parameters.
Particlelike distributions of the Higgs field nonminimally coupled to gravity
Andre Fuzfa; Massimiliano Rinaldi; Sandrine Schlogel
2013-09-10T23:59:59.000Z
When the Higgs field is nonminimally coupled to gravity, there exists a family of spherically symmetric particlelike solutions to the field equations. These monopoles are the only globally regular and asymptotically flat distributions with finite energy of the Higgs field around compact objects. Moreover, spontaneous scalarization is strongly amplified for specific values of their mass and compactness.
Emergent/Quantum Gravity: Macro/Micro Structures of Spacetime
B. L. Hu
2009-03-04T23:59:59.000Z
Emergent gravity views spacetime as an entity emergent from a more complete theory of interacting fundamental constituents valid at much finer resolution or higher energies, usually assumed to be above the Planck energy. In this view general relativity is an effective theory valid only at long wavelengths and low energies. For any presumed known theory for the microscopic structure of spacetime, we describe common tasks of emergent gravity (`top-down'), namely, identifying the conditions and processes or mechanisms whereby the familiar macroscopic spacetime emerges with high probability and reasonable robustness. Going in the opposite direction (`bottom-up') is the task of quantum gravity, i.e., finding a theory for the microscopic structure of spacetime, which, in this new view, cannot come from quantizing the metric or connection forms because they are the collective variables which are meaningful only for the macroscopic theory, i.e., general relativity. We suggest pathways to move `up' (in energy) from the given macroscopic conditions of classical gravity and quantum field theory to the domain closer to the micro-macro interface where spacetime emerged and places to look for clues or tell-tale signs at low energy where one could infer indirectly some salient features of the micro-structure of spacetime.
GRAVITY DRIVEN SHALLOW WATER MODELS FOR ARBITRARY TOPOGRAPHY
Blömker, Dirk
GRAVITY DRIVEN SHALLOW WATER MODELS FOR ARBITRARY TOPOGRAPHY FRANC¸OIS BOUCHUT AND MICHAEL over a general topography. A first model is valid for small slope variation, i.e. small curvature, and a second model is valid for arbitrary topography. In both cases no particular assumption is made
Einstein static Universe in hybrid metric-Palatini gravity
Christian G. Boehmer; Francisco S. N. Lobo; Nicola Tamanini
2015-02-18T23:59:59.000Z
Hybrid metric-Palatini gravity is a recent and novel approach to modified theories of gravity, which consists of adding to the metric Einstein-Hilbert Lagrangian an f(R) term constructed a la Palatini. It was shown that the theory passes local tests even if the scalar field is very light, and thus implies the existence of a long-range scalar field, which is able to modify the dynamics in galactic and cosmological scales, but leaves the Solar System unaffected. In this work, motivated by the possibility that the Universe may have started out in an asymptotically Einstein static state in the inflationary universe context, we analyse the stability of the Einstein static Universe by considering linear homogeneous perturbations in the respective dynamically equivalent scalar-tensor representation of hybrid metric-Palatini gravity. Considering linear homogeneous perturbations, the stability regions of the Einstein static universe are parametrized by the first and second derivatives of the scalar potential, and it is explicitly shown that a large class of stable solutions exists in the respective parameter space, in the context of hybrid metric-Palatini gravity.
Einstein static Universe in non-minimal kinetic coupled gravity
K. Atazadeh; F. Darabi
2015-04-18T23:59:59.000Z
We study the stability of Einstein static Universe, with FLRW metric, by considering linear homogeneous perturbations in the kinetic coupled gravity. By taking linear homogeneous perturbations, we find that the stability of Einstein static Universe, in the kinetic coupled gravity with quadratic scalar field potential, for closed ($K=1$) isotropic and homogeneous FLRW Universe depends on the coupling parameters $\\kappa$ and $\\varepsilon$. Specifically, for $\\kappa=L_P^2$ and $\\varepsilon=1$ we find that the stability condition imposes the inequality $a_0>\\sqrt{3}L_P$ on the initial size $a_0$ of the closed Einstein static Universe before the inflation. Such inequality asserts that the initial size of the Einstein static Universe must be greater than the Planck length $L_P$, in consistency with the quantum gravity and quantum cosmology requirements. In this way, we have determined the non-minimal coupling parameter $\\kappa$ in the context of Einstein static Universe. Such a very small parameter is favored in the inflationary models constructed in the kinetic coupled gravity. We have also studied the stability against the vector and tensor perturbations and discussed on the acceptable values of the equation of state parameter.
Deformed Reissner-Nordstrom solutions in noncommutative gravity
Mukherjee, Pradip [Department of Physics, Presidency College, 86/1 College Street, Kolkata-700073, West Bengal (India); Saha, Anirban [Department of Physics, Sovarani Memorial College, Jagatballavpur, Howrah-711 408, West Bengal (India)
2008-03-15T23:59:59.000Z
The leading order corrections to Reissner-Nordstrom solutions of the Einstein's equations on noncommutative spacetime have been worked out based on a noncommutative gauge theory of gravity. From the corrected metric the horizons have been derived and the curvature scalar is also computed. The introduction of noncommutativity leads to the removal of the coordinate singularities.
3D Quantum Gravity and Effective Noncommutative Quantum Field Theory
Freidel, Laurent; Livine, Etera R. [Perimeter Institute, 31 Caroline Street, North Waterloo, Ontario N2L 2Y5, Canada, and Laboratoire de Physique, ENS Lyon, CNRS UMR 5672, 46 Allee d'Italie, 69364 Lyon Cedex 07 (France)
2006-06-09T23:59:59.000Z
We show that the effective dynamics of matter fields coupled to 3D quantum gravity is described after integration over the gravitational degrees of freedom by a braided noncommutative quantum field theory symmetric under a {kappa} deformation of the Poincare group.
Free energy of topologically massive gravity and flat space holography
Daniel Grumiller; Wout Merbis
2015-09-28T23:59:59.000Z
We calculate the free energy from the on-shell action for topologically massive gravity with negative and vanishing cosmological constant, thereby providing a first principles derivation of the free energy of BTZ black holes and flat space cosmologies. We summarize related recent checks of flat space holography.
Free energy of topologically massive gravity and flat space holography
Grumiller, Daniel
2015-01-01T23:59:59.000Z
We calculate the free energy from the on-shell action for topologically massive gravity with negative and vanishing cosmological constant, thereby providing a first principles derivation of the free energy of BTZ black holes and flat space cosmologies. We summarize related recent checks of flat space holography.
Constraints on massive gravity theory from big bang nucleosynthesis
G. Lambiase
2012-08-27T23:59:59.000Z
The massive gravity cosmology is studied in the scenario of big bang nucleosynthesis. By making use of current bounds on the deviation from the fractional mass, we derive the constraints on the free parameters of the theory. The cosmological consequences of the model are also discussed in the framework of the PAMELA experiment.
Testing gravity with halo density profiles observed through gravitational lensing
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
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.
The Unified Theory - Electricity, Magnetism, Gravity and Mechanics
Pretterebner Julius
1999-08-12T23:59:59.000Z
This article shows the relations between the electricity, magnetism, gravity and mechanics by presenting an existing hidden structure in the Maxwell equations. This hidden structure allows to discover the classical physic from a new point of view leading to the unified theory (UT).
Testing gravity on kiloparsec scales with strong gravitational lenses
Tristan L. Smith
2010-04-12T23:59:59.000Z
Modifications to GR generically predict time and scale-dependent effects which may be probed by observations of strong lensing by galaxies. Measurements of the stellar velocity dispersion determine the dynamical mass whereas measurements of the Einstein radius determine the lensing mass. In GR these two masses are equal; in alternative gravity theories they may not be. Using measurements of the stellar velocity dispersion and strong lensing around galaxies from the Sloan Lens ACS (SLACS) survey we place constraints on lensing in modified gravity theories and extend previous studies by applying this data to explore its dependence on various properties of the lens such as the lens redshift or mass and thereby constrain scalar-tensor, f(R) gravity theories, and generic parameterizations of deviations from GR. Besides applying the observations to these specific gravity theories, the data places a constraint on a generic dependence of modifications to GR on the lens mass and redshift. At the 68% confidence level we find that the ratio between the lensing and dynamical masses can only vary by less then 50% over a mass range for the lens galaxies of 1E12 < M/Msun < 1E14 and less than 40% over the redshift range 0.06 < z < 0.36.
Gauge/Gravity Theory with Running Dilaton and Running Axion
Girma Hailu
2007-12-27T23:59:59.000Z
We present a new gauge/gravity duality construction of the Klebanov-Strassler throat which takes corrections to the anomalous mass dimension proposed in [1] into account on the gauge theory side and both the dilaton and the axion run on the gravity side. The corresponding supergravity solutions are found using equations for type IIB flows with N=1 supersymmetry obtained in [2]. We find that magnetic couplings of the axion to D7-branes filling 4-d spacetime and wrapping 4-cycles at locations of duality transitions and invisible Dirac 8-branes whose worldvolume emanates from the worldvolume of the D7-branes are the sources for the runnings of the dilaton and the axion. Our construction provides the first explicit example of a gauge/gravity duality mapping with a running dilaton or a running axion which is an important component towards finding gravity duals to gauge theories with physically more interesting renormalization group flows such as pure confining gauge theories in four dimensions. The D7-branes also serve as gravitational source for Seiberg duality transitions. The supergravity background has distinct features which could be useful for constructing cosmological models and studying possibilities for probing stringy signatures from the early universe.
Granular physics in low-gravity environments using DEM
G. Tancredi; A. Maciel; L. Heredia; P. Richeri; S. Nesmachnow
2011-11-26T23:59:59.000Z
Granular materials of different sizes are present on the surface of several atmosphere-less Solar System bodies. The phenomena related to granular materials have been studied in the framework of the discipline called Granular Physics; that has been studied experimentally in the laboratory and, in the last decades, by performing numerical simulations. The Discrete Element Method simulates the mechanical behavior of a media formed by a set of particles which interact through their contact points. The difficulty in reproducing vacuum and low-gravity environments makes numerical simulations the most promising technique in the study of granular media under these conditions. In this work, relevant processes in minor bodies of the Solar System are studied using the Discrete Element Method. Results of simulations of size segregation in low-gravity environments in the cases of the asteroids Eros and Itokawa are presented. The segregation of particles with different densities was analysed, in particular, the case of comet P/Hartley 2. The surface shaking in these different gravity environments could produce the ejection of particles from the surface at very low relative velocities. The shaking causing the above processes is due to: impacts, explosions like the release of energy by the liberation of internal stresses or the re accommodation of material. Simulations of the passage of impact-induced seismic waves through a granular medium were also performed. We present several applications of the Discrete Element Methods for the study of the physical evolution of agglomerates of rocks under low-gravity environments.
Kac-Moody algebras in gravity and M-theories
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
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.
Entirely passive heat pipe apparatus capable of operating against gravity
Koenig, Daniel R. (Santa Fe, NM)
1982-01-01T23:59:59.000Z
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.
Cartan gravity, matter fields, and the gauge principle
Westman, Hans F., E-mail: hwestman74@gmail.com [Imperial College Theoretical Physics, Huxley Building, London, SW7 2AZ (United Kingdom); Zlosnik, Tom G., E-mail: t.zlosnik@imperial.ac.uk [Instituto de Física Fundamental, CSIC, Serrano 113-B, 28006 Madrid (Spain)
2013-07-15T23:59:59.000Z
Gravity is commonly thought of as one of the four force fields in nature. However, in standard formulations its mathematical structure is rather different from the Yang–Mills fields of particle physics that govern the electromagnetic, weak, and strong interactions. This paper explores this dissonance with particular focus on how gravity couples to matter from the perspective of the Cartan-geometric formulation of gravity. There the gravitational field is represented by a pair of variables: (1) a ‘contact vector’ V{sup A} which is geometrically visualized as the contact point between the spacetime manifold and a model spacetime being ‘rolled’ on top of it, and (2) a gauge connection A{sub ?}{sup AB}, here taken to be valued in the Lie algebra of SO(2,3) or SO(1,4), which mathematically determines how much the model spacetime is rotated when rolled. By insisting on two principles, the gauge principle and polynomial simplicity, we shall show how one can reformulate matter field actions in a way that is harmonious with Cartan’s geometric construction. This yields a formulation of all matter fields in terms of first order partial differential equations. We show in detail how the standard second order formulation can be recovered. In particular, the Hodge dual, which characterizes the structure of bosonic field equations, pops up automatically. Furthermore, the energy–momentum and spin-density three-forms are naturally combined into a single object here denoted the spin-energy–momentum three-form. Finally, we highlight a peculiarity in the mathematical structure of our first-order formulation of Yang–Mills fields. This suggests a way to unify a U(1) gauge field with gravity into a SO(1,5)-valued gauge field using a natural generalization of Cartan geometry in which the larger symmetry group is spontaneously broken down to SO(1,3)×U(1). The coupling of this unified theory to matter fields and possible extensions to non-Abelian gauge fields are left as open questions. -- Highlights: •Develops Cartan gravity to include matter fields. •Coupling to gravity is done using the standard gauge prescription. •Matter actions are manifestly polynomial in all field variables. •Standard equations recovered on-shell for scalar, spinor and Yang–Mills fields. •Unification of a U(1) field with gravity based on the orthogonal group SO(1,5)
Gravity monitoring of CO2 movement during sequestration: Model studies
Gasperikova, E.; Hoversten, G.M.
2008-07-15T23:59:59.000Z
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.
Goedel-type universes in Palatini f(R) gravity
Santos, J.; Oliveira, T. B. R. F. [Universidade Federal do Rio Grande do Norte, Departamento de Fisica, 59072-970 Natal-RN (Brazil); Reboucas, M. J. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro-RJ (Brazil)
2010-06-15T23:59:59.000Z
We examine the question as to whether the Palatini f(R) gravity theories permit space-times in which the causality is violated. We show that every perfect-fluid Goedel-type solution of Palatini f(R) gravity with density {rho} and pressure p that satisfy the weak energy condition {rho}+p{>=}0 is necessarily isometric to the Goedel geometry, demonstrating therefore that these theories present causal anomalies in the form of closed timelike curves. This result extends a theorem on Goedel-type models to the framework of Palatini f(R) gravity theory. We concretely examine the Goedel-type perfect-fluid solutions in specific f(R)=R-{alpha}/R{sup n} Palatini gravity theory, where the free parameters {alpha} and n have been recently constrained by observational data. We show that for positive matter density and for {alpha} and n within the interval permitted by the observations, this theory does not admit the Goedel geometry as a perfect-fluid solution of its field equations. In this sense, this theory remedies the causal pathology in the form of closed timelike curves which is allowed in general relativity. We derive an expression for a critical radius r{sub c} (beyond which the causality is violated) for an arbitrary Palatini f(R) theory. The expression makes apparent that the violation of causality depends on the form of f(R) and on the matter content components. We also examine the violation of causality of Goedel-type by considering a single scalar field as the matter content. For this source we show that Palatini f(R) gravity gives rise to a unique Goedel-type solution with no violation of causality.
Native American Support Programs Task Force Changing Winds: Service to Native American Students
Maxwell, Bruce D.
and Communities in Montana Final Report of the MSU Native American Support Programs Task Force Submitted To Shelly Hogan #12;Native American Support Programs Task Force Contents EXECUTIVE SUMMARY TO STUDENT SUCCESS 12 FIGURE 6 WAYS TO ACHIEVE PROGRAM IMPROVEMENT 12 FIGURE 7 EMERGING THEMES: WHAT
Garfinkle, David
2015-01-01T23:59:59.000Z
GGR News: We Hear That ... Advanced LIGO in mid-2015 GGR dominates April APS meeting Conference Reports: GaryFest
Multi-gravity separator: an alternate gravity concentrator to process coal fines
Majumder, A.K.; Bhoi, K.S.; Barnwal, J.P. [Regional Research Laboratories, Bhopal (India)
2007-08-15T23:59:59.000Z
The multi-gravity separator (MGS) is a novel piece of equipment for the separation of fine and ultra-fine minerals. However, the published literature does not demonstrate its use in the separation of coal fines. Therefore, an attempt was made to study the effects of different process variables on the performance of an MGS for the beneficiation of coal fines. The results obtained from this study revealed that among the parameters studied, drum rotation and feed solids concentration play dominating roles in controlling the yield and ash content of the clean coal. Mathematical modeling equations that correlate the variables studied and the yield and ash contents of the clean coal were developed to predict the performance of an MGS under different operating and design conditions. The entire exercise revealed that the MGS could produce a clean coal with an ash content of 14.67% and a yield of 71.23% from a feed coal having an ash content of 24.61 %.
Women weaving the dream of the revolution in the American continent
Angeleri, Sandra
2006-01-01T23:59:59.000Z
Americanism. South American integration is the BolivarianChávez’s South American project of integration. A fewintegration. President Chávez, paralleling Garcia Canclini’s ideas extends the South American
Kokontis, Kate Menninger
2011-01-01T23:59:59.000Z
of Immigration, Italian-ness, and the Port-of-Entry: on thecitizenship, American-ness, and belonging) and blackness (and therefore American-ness, has come to mean. 5 Thus it is
New Directions in Technical Services For Latin American collections: Building unique collections
Harvell, Tony
2010-01-01T23:59:59.000Z
Technical Services For Latin American collections: Buildingunique collections Tony Harvell Latin American Studiestransformation • Diminished collections budgets • Increased
Single nucleotide polymorphism discovery in elite north american potato germplasm
Douches, David S.
Single nucleotide polymorphism discovery in elite north american potato germplasm Hamilton et al;RESEARCH ARTICLE Open Access Single nucleotide polymorphism discovery in elite north american potato breeding approaches in potato rely almost entirely on phenotypic evaluations; molecular markers
Native American Fish and Wildlife Society Pacific Region Conference...
Office of Environmental Management (EM)
Native American Fish and Wildlife Society Pacific Region Conference Native American Fish and Wildlife Society Pacific Region Conference October 13, 2015 8:00AM MDT to October 15,...
Job Opening at American Android Corp. Position: Software Engineer
Plotkin, Joshua B.
Job Opening at American Android Corp. Position: Software Engineer Location: Princeton, New Jersey Job Description: American Android Corp. (www.americanandroid.com) develops humanoid robots modeling, and robot behavior development. Job Requirements: BS in computer science, robotics or related
Agricultural Development in theAmerican Pacific (ADAP)
Agricultural Development in theAmerican Pacific (ADAP) Project ImpactReport 1988-2004 #12;VISION Agricultural Development in the American Pacific (ADAP) project enables sustainable environments, diverse agriculture and communities through collaborative programs that are culturally appropriate, socially
21H.101 American History to 1865, Fall 2005
Maier, Pauline
This course focuses on a basic history of American social, economic, and political development from the colonial period through the Civil War. The colonial heritages of Spanish and British America; the American Revolution ...
AIAA-98-0049 American Institute of Aeronautics and Astronautics
AIAA-98-0049 1 American Institute of Aeronautics and Astronautics ESTIMATION OF UNCERTAIN MATERIAL-0049 2 American Institute of Aeronautics and Astronautics Simple tests can be used to measure effective
Home Front as Warfront: African American World War I Drama
Egging, Anna Katherine
2010-08-31T23:59:59.000Z
This dissertation recovers little-known African American World War I plays that blur the boundary between the home front and warfront. I argue that with this focus, the plays wage their own war for African American citizenship ...
ENERGY STAR Residential Water Heaters to Save Americans Up to...
ENERGY STAR Residential Water Heaters to Save Americans Up to 823 Million in the Next Five Years ENERGY STAR Residential Water Heaters to Save Americans Up to 823 Million in the...
Pure Geometric Field Theory: Description of Gravity and Material Distribution
M. I. Wanas; Nabil L. Youssef; W. El Hanafy
2015-03-31T23:59:59.000Z
A field theory is constructed in the context of parameterized absolute parallelism\\linebreak geometry. The theory is shown to be a pure gravity one. It is capable of describing the gravitational field and a material distribution in terms of the geometric structure of the geometry used (the parallelization vector fields). Three tools are used to attribute physical properties to the geometric objects admitted by the theory. Poisson and Laplace equations are obtained in the linearized version of the theory. The spherically symmetric solution of the theory, in free space, is found to coincide with the Schwarzschild exterior solution of the general theory of relativity. The theory respects the weak equivalence principle in free space only. Gravity and material distribution are not minimally coupled.
Fourth order gravity: equations, history, and applications to cosmology
H. -J. Schmidt
2006-03-25T23:59:59.000Z
The field equations following from a Lagrangian L(R) will be deduced and solved for special cases. If L is a non-linear function of the curvature scalar, then these equations are of fourth order in the metric. In the introduction we present the history of these equations beginning with the paper of H. Weyl from 1918, who first discussed them as alternative to Einstein's theory. In the third part, we give details about the cosmic no hair theorem, i.e., the details how within fourth order gravity with L= R + R^2 the inflationary phase of cosmic evolution turns out to be a transient attractor. Finally, the Bicknell theorem, i.e. the conformal relation from fourth order gravity to scalar-tensor theory, will be shortly presented.
Introduction to Modified Gravity and Gravitational Alternative for Dark Energy
Nojiri, S
2006-01-01T23:59:59.000Z
We review various modified gravities considered as gravitational alternative for dark energy. Specifically, we consider the versions of $f(R)$, $f(G)$ or $f(R,G)$ gravity, model with non-linear gravitational coupling or string-inspired model with Gauss-Bonnet-dilaton coupling in the late universe where they lead to cosmic speed-up. It is shown that some of such theories may pass the Solar System tests. On the same time, it is demonstrated that they have quite rich cosmological structure: they may naturally describe the effective (cosmological constant, quintessence or phantom) late-time era with a possible transition from decceleration to acceleration thanks to gravitational terms which increase with scalar curvature decrease. The possibility to explain the coincidence problem as the manifestation of the universe expansion in such models is mentioned. The late (phantom or quintessence) universe filled with dark fluid with inhomogeneous equation of state (where inhomogeneous terms are originated from the modif...
Climate variability according to triple saros gravity cycles
William R. Livingston
2013-06-03T23:59:59.000Z
I describe a climate model which corresponds directly to eclipse cycles. The theory is based upon a similarity between the 54 year triple saros eclipse period and the periodicity of drought. I argue that eclipse shadows are an indication of gravity cycles, and that variable lunar gravitation is the most significant aspect of the eclipse process. I reinforce the idea that lunar gravitational forcing has a profound effect on the water vapor in Earth's atmosphere, and can affect the density and location of clouds. I explore the possibility that decadal variability of ocean surface levels may be explained by triple saros gravity cycles. I point out that lunar gravitation was excluded from the most significant climate report of 2007, and that climate data contradictions have been overlooked by researchers. I focus on the value of data that has not been aggregated into global averages. I touch upon the history of global warming, and I offer predictions based upon 54 year climate periodicity.
Trapping and aerogelation of nanoparticles in negative gravity hydrocarbon flames
Chakrabarty, Rajan K., E-mail: rajan.chakrabarty@gmail.com [Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130 (United States); Laboratory for Aerosol Science, Spectroscopy, and Optics, Desert Research Institute, Nevada System of Higher Education, Reno, Nevada 89512 (United States); Novosselov, Igor V. [Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States); Enertechnix Inc., Maple Valley, Washington 98068 (United States); Beres, Nicholas D.; Moosmüller, Hans [Laboratory for Aerosol Science, Spectroscopy, and Optics, Desert Research Institute, Nevada System of Higher Education, Reno, Nevada 89512 (United States); Sorensen, Christopher M. [Condensed Matter Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); Stipe, Christopher B. [TSI Incorporated, 500 Cardigan Rd, Shoreview, Minnesota 55126 (United States)
2014-06-16T23:59:59.000Z
We report the experimental realization of continuous carbon aerogel production using a flame aerosol reactor by operating it in negative gravity (?g; up-side-down configuration). Buoyancy opposes the fuel and air flow forces in ?g, which eliminates convectional outflow of nanoparticles from the flame and traps them in a distinctive non-tipping, flicker-free, cylindrical flame body, where they grow to millimeter-size aerogel particles and gravitationally fall out. Computational fluid dynamics simulations show that a closed-loop recirculation zone is set up in ?g flames, which reduces the time to gel for nanoparticles by ?10{sup 6}?s, compared to positive gravity (upward rising) flames. Our results open up new possibilities of one-step gas-phase synthesis of a wide variety of aerogels on an industrial scale.
Induced Matter Brane Gravity and Einstein Static Universe
Y. Heydarzade; F. Darabi
2015-04-21T23:59:59.000Z
We investigate stability of the Einstein static universe against the scalar, vector and tensor perturbations in the context of induced matter brane gravity. It is shown that in the framework of this model, the Einstein static universe has a positive spatial curvature. In contrast to the classical general relativity, it is found that a stable Einstein static universe against the scalar perturbations does exist provided that the variation of time dependent geometrical equation of state parameter is proportional to the minus of the variation of the scale factor, $\\delta \\omega_{g}(t)=-C\\delta a(t)$. We obtain neutral stability against the vector perturbations, and the stability against the tensor perturbations is guaranteed due to the positivity of the spatial curvature of the Einstein static universe in induced matter brane gravity.
Evaluation of an Impulse Gravity Generator Based Beamed Propulsion Concept
Giovanni Modanese; Chris Y. Taylor
2002-09-05T23:59:59.000Z
This paper analyzes the suitability of a beamed propulsion concept having properties consistent with the impulse gravity generator described by Podkletnov et al. [physics/0108005]. The use of this propulsion concept for orbital maneuver, Earth-to-orbit, interplanetary, and interstellar applications based on presently available experimental results and theory is considered, and areas for future research needed to better characterize this phenomenon are discussed. A beam of radiation or particles with the properties described for the impulse gravity generator would appear to be an excellent candidate for use in beamed spacecraft propulsion. Besides the usual benefits of beamed propulsion, it would not need sails or other special spacecraft components to function, could safely provide high accelerations to delicate components, and might operate at higher efficiencies than other beamed propulsion concepts.
Holographic renormalization and anisotropic black branes in higher curvature gravity
Viktor Jahnke; Anderson Seigo Misobuchi; Diego Trancanelli
2014-12-30T23:59:59.000Z
We consider five-dimensional AdS-axion-dilaton gravity with a Gauss-Bonnet term and find a solution of the equations of motion which corresponds to a black brane exhibiting a spatial anisotropy, with the source of the anisotropy being an axion field linear in one of the horizon coordinates. Our solution is static, regular everywhere on and outside the horizon, and asymptotically AdS. It is analytic and valid in a small anisotropy expansion, but fully non-perturbative in the Gauss-Bonnet coupling. We discuss various features of this solution and use it as a gravity dual to a strongly coupled anisotropic plasma with two independent central charges, $a\
Modelling gravity on a hyper-cubic lattice
Tate, Kyle
2012-01-01T23:59:59.000Z
We present an elegant and simple dynamical model of symmetric, non-degenerate (n x n) matrices of fixed signature defined on a n-dimensional hyper-cubic lattice with nearest-neighbor interactions. We show how this model is related to General Relativity, and discuss multiple ways in which it can be useful for studying gravity, both classical and quantum. In particular, we show that the dynamics of the model when all matrices are close to the identity corresponds exactly to a finite-difference discretization of weak-field gravity in harmonic gauge. We also show that the action which defines the full dynamics of the model corresponds to the Einstein-Hilbert action to leading order in the lattice spacing, and use this observation to define a lattice analogue of the Ricci scalar and Einstein tensor. Finally, we perform a mean-field analysis of the statistical mechanics of this model.
Signature change events: A challenge for quantum gravity?
White, Angela; Visser, Matt
2008-01-01T23:59:59.000Z
Within the framework of either Euclidian (functional-integral) quantum gravity or canonical general relativity the signature of the manifold is a priori unconstrained. Furthermore, recent developments in the emergent spacetime programme have led to a physically feasible implementation of signature change events. This suggests that it is time to revisit the sometimes controversial topic of signature change in general relativity. Specifically, we shall focus on the behaviour of a quantum field subjected to a manifold containing regions of different signature. We emphasise that, regardless of the underlying classical theory, there are severe problems associated with any quantum field theory residing on a signature-changing background. (Such as the production of what is naively an infinite number of particles, with an infinite energy density.) From the viewpoint of quantum gravity phenomenology, we discuss possible consequences of an effective Lorentz symmetry breaking scale. To more fully understand the physics ...
Cloud of strings for radiating black holes in Lovelock gravity
Sushant G. Ghosh; Sunil D. Maharaj
2014-09-28T23:59:59.000Z
We present exact spherically symmetric null dust solutions in the third order Lovelock gravity with a string cloud background in arbitrary $N$ dimensions,. This represents radiating black holes and generalizes the well known Vaidya solution to Lovelock gravity with a string cloud in the background. We also discuss the energy conditions and horizon structures, and explicitly bring out the effect of the string clouds on the horizon structure of black hole solutions for the higher dimensional general relativity and Einstein-Gauss-Bonnet theories. It turns out that the presence of the coupling constant of the Gauss-Bonnet terms and/or background string clouds completely changes the structure of the horizon and this may lead to a naked singularity. We recover known spherically symmetric radiating models as well as static black holes in the appropriate limits.
f(R) Gravity, relic coherent gravitons and optical chaos
Lawrence B. Crowell; Christian Corda
2014-02-19T23:59:59.000Z
We discuss the production of massive relic coherent gravitons in a particular class of f(R) gravity which arises from string theory and their possible imprint in Cosmic Microwave Background. In fact, in the very early universe these relic gravitons could have acted as slow gravity waves. They may have then acted to focus the geodesics of radiation and matter. Therefore, their imprint on the later evolution of the universe could appear as filaments and domain wall in the Universe today. In that case, the effect on Cosmic Microwave Background should be analogous to the effect of water waves, which, in focusing light, create optical caustics which are commonly seen on the bottom of swimming pools. We analyze this important issue by showing how relic massive GWs perturb the trajectories of Cosmic Microwave Background photons (gravitational lensing by relic GWs). The consequence of the type of physics discussed is outlined by illustrating an amplification of what might be called optical chaos.
Energy and stability analysis of mimetic-f(R) gravity
Haghani, Zahra; Shiravand, Maryam
2015-01-01T23:59:59.000Z
The energy conditions of mimetic-$f(R)$ gravity theory, together with the Dolgov-Kawasaki instability will be analysed. It will be shown that the condition for the stability of the theory against Dolgov-Kawasaki is equivalent to the standard $f(R)$ gravity theory. We will also show that the exact de Sitter solution for the theory can only be obtained by an exponential form for the function $f(R)$. The Brans-Dicke equivalence of the theory is also discussed in more details. We will obtain the parameter space of the theory in an exponential and power law forms of $f(R)$, for violating the strong energy condition while satisfying the weak, null and dominant energy conditions.
CP-safe Gravity Mediation and Muon g-2
Sho Iwamoto; Tsutomu T. Yanagida; Norimi Yokozaki
2015-02-03T23:59:59.000Z
We propose a CP-safe gravity mediation model, where the phases of the Higgs B parameter, scalar trilinear couplings and gaugino mass parameters are all aligned. Since all dangerous CP violating phases are suppressed, we are now safe to consider low-energy SUSY scenarios. As an application, we consider a gravity mediation model explaining the observed muon $g-2$ anomaly. The CP-safe property originates in two simple assumptions: SUSY breaking in the K\\"ahler potential and a shift symmetry of a SUSY breaking field $Z$. As a result of the shift symmetry, the imaginary part of $Z$ behaves as a QCD axion, leading to an intriguing possibility: the strong CP problem in QCD and the SUSY CP problem are solved simultaneously.
Clouds of strings in third-order Lovelock gravity
Sushant G. Ghosh; Uma Papnoi; Sunil D. Maharaj
2014-08-20T23:59:59.000Z
Lovelock theory is a natural extension of the Einstein theory of general relativity to higher dimensions in which the first and second orders correspond, respectively, to general relativity and Einstein-Gauss-Bonnet gravity. We present exact black hole solutions of $D\\geq 4$-dimensional spacetime for first-, second-, and third-order Lovelock gravities in a string cloud background. Further, we compute the mass, temperature, and entropy of black hole solutions for the higher-dimensional general relativity and Einstein-Gauss-Bonnet theories and also perform thermodynamic stability of black holes. It turns out that the presence of the Gauss-Bonnet term and/or background string cloud completely changes the black hole thermodynamics. Interestingly, the entropy of a black hole is unaffected due to a background string cloud. We rediscover several known spherically symmetric black hole solutions in the appropriate limits.
Is Holographic Entropy and Gravity the result of Quantum Mechanics?
Joakim Munkhammar
2010-03-09T23:59:59.000Z
In this paper we suggest a connection between quantum mechanics and Verlinde's recently proposed entropic force theory for the laws of Newton. We propose an entropy based on the quantum mechanical probability density distribution. With the assumption that the holographic principle holds we propose that our suggested quantum entropy generalizes the Bekenstein entropy used by Verlinde in his approach. Based on this assumption we suggest that Verlinde's entropic theory of gravity has a quantum mechanical origin. We establish a reformulation of the Newtonian potential for gravity based on this quantum mechanical entropy. We also discuss the notion of observation and the correspondence to classical physics. Finally we give a discussion, a number of open problems and some concluding remarks.
Giant black hole ringings induced by massive gravity
Yves Decanini; Antoine Folacci; Mohamed Ould El Hadj
2014-01-01T23:59:59.000Z
A distorted black hole radiates gravitational waves in order to settle down in one of the geometries permitted by the no-hair theorem. During that relaxation phase, a characteristic damped ringing is generated. It can be theoretically constructed from the black hole quasinormal frequencies (which govern its oscillating behavior and its decay) and from the associated excitation factors (which determine intrinsically its amplitude) by carefully taking into account the source of the distortion. Here, by considering the Schwarzschild black hole in the framework of massive gravity, we show that the excitation factors have an unexpected strong resonant behavior leading to giant ringings which are, moreover, slowly decaying. Such extraordinary black hole ringings could be observed by the next generations of gravitational wave detectors and allow us to test the various massive gravity theories or their absence could be used to impose strong constraints on the graviton mass.
Weak Gravity Strongly Constrains Large-Field Axion Inflation
Ben Heidenreich; Matthew Reece; Tom Rudelius
2015-06-10T23:59:59.000Z
Models of large-field inflation based on axion-like fields with shift symmetries can be simple and natural, and make a promising prediction of detectable primordial gravitational waves. The Weak Gravity Conjecture is known to constrain the simplest case in which a single axion descends from a gauge field in an extra dimension. By supplementing the Weak Gravity Conjecture with considerations of how the mass spectrum of the theory varies across the axion moduli space, we obtain more powerful constraints that apply to a variety of multi-axion theories including N-flation and alignment models. In every case that we consider, plausible assumptions lead to field ranges that cannot be parametrically larger than the Planck scale. Our results are strongly suggestive of a general inconsistency in models of large-field inflation based on axions, and possibly of a more general principle forbidding super-Planckian field ranges.
Constraints on Axion Inflation from the Weak Gravity Conjecture
Rudelius, Tom
2015-01-01T23:59:59.000Z
We derive constraints facing models of axion inflation based on decay constant alignment from a string-theoretic and quantum gravitational perspective. In particular, we investigate the prospects for alignment and `anti-alignment' of $C_4$ axion decay constants in type IIB string theory, deriving a strict no-go result in the latter case. We discuss the relationship of axion decay constants to the weak gravity conjecture and demonstrate agreement between our string-theoretic constraints and those coming from the `generalized' weak gravity conjecture. Finally, we consider a particular model of decay constant alignment in which the potential of $C_4$ axions in type IIB compactifications on a Calabi-Yau three-fold is dominated by contributions from $D7$-branes, pointing out that this model evades some of the challenges derived earlier in our paper but is highly constrained by other geometric considerations.
Weak Gravity Strongly Constrains Large-Field Axion Inflation
Heidenreich, Ben; Rudelius, Tom
2015-01-01T23:59:59.000Z
Models of large-field inflation based on axion-like fields with shift symmetries can be simple and natural, and make a promising prediction of detectable primordial gravitational waves. The Weak Gravity Conjecture is known to constrain the simplest case in which a single axion descends from a gauge field in an extra dimension. By supplementing the Weak Gravity Conjecture with considerations of how the mass spectrum of the theory varies across the axion moduli space, we obtain more powerful constraints that apply to a variety of multi-axion theories including N-flation and alignment models. In every case that we consider, plausible assumptions lead to field ranges that cannot be parametrically larger than the Planck scale. Our results are strongly suggestive of a general inconsistency in models of large-field inflation based on axions, and possibly of a more general principle forbidding super-Planckian field ranges.
Constraining f(T) gravity in the Solar System
Iorio, Lorenzo; Ruggiero, Matteo Luca
2015-01-01T23:59:59.000Z
In the framework of $f(T)$ theories of gravity, we solve the field equations for $f(T)=T+\\alpha T^{n}$, in the weak-field approximation and for spherical symmetry spacetime. Since $f(T)=T$ corresponds to Teleparallel Gravity, which is equivalent to General Relativity, the non linearity of the Lagrangian are expected to produce perturbations of the general relativistic solutions, parameterized by $\\alpha$. Hence, we use the $f(T)$ solutions to model the gravitational field of the Sun, and exploit data from accurate tracking of spacecrafts orbiting Mercury and Saturn to infer preliminary insights on what could be obtained about the model parameter $\\alpha$ and the cosmological constant $\\Lambda$. It turns out that improvements of about one-three orders with respect to the present-day constraints in the literature of magnitude seem possible.
The Weak-Coupling Limit of Simplicial Quantum Gravity
G. Thorleifsson; P. Bialas; B. Petersson
1998-12-23T23:59:59.000Z
In the weak-coupling limit, kappa_0 going to infinity, the partition function of simplicial quantum gravity is dominated by an ensemble of triangulations with the ratio N_0/N_D close to the upper kinematic limit. For a combinatorial triangulation of the D--sphere this limit is 1/D. Defining an ensemble of maximal triangulations, i.e. triangulations that have the maximal possible number of vertices for a given volume, we investigate the properties of this ensemble in three dimensions using both Monte Carlo simulations and a strong-coupling expansion of the partition function, both for pure simplicial gravity and a with a suitable modified measure. For the latter we observe a continuous phase transition to a crinkled phase and we investigate the fractal properties of this phase.
Quantizing Horava-Lifshitz gravity via causal dynamical triangulations
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Anderson, Christian; Carlip, Steven J.; Cooperman, Joshua H.; Ho?ava, Petr; Kommu, Rajesh K.; Zulkowski, Patrick R.
2012-02-01T23:59:59.000Z
We extend the discrete Regge action of causal dynamical triangulations to include discrete versions of the curvature squared terms appearing in the continuum action of (2+1)-dimensional projectable Horava-Lifshitz gravity. Focusing on an ensemble of spacetimes whose spacelike hypersurfaces are two-spheres, we employ Markov chain Monte Carlo simulations to study the path integral defined by this extended discrete action. We demonstrate the existence of known and novel macroscopic phases of spacetime geometry, and we present preliminary evidence for the consistency of these phases with solutions to the equations of motion of classical Horava-Lifshitz gravity. Apparently, the phase diagram contains a phase transition between a time-dependent de Sitter-like phase and a time-independent phase. We speculate that this phase transition may be understood in terms of deconfinement of the global gravitational Hamiltonian integrated over a spatial two-sphere.
Solar-System Constraints on f(R) Chameleon Gravity
Je-An Gu; Wei-Ting Lin
2011-08-08T23:59:59.000Z
We investigate the solar-system constraint on the f(R) theory of modified gravity with chameleon mechanism, where f(R) represents the deviation from general relativity in the gravity action. We obtain a stringent bound to a general, non-constant deviation function f(R): -10^{-15} 3*10^5*H0^2, by requiring the thin-shell condition in the solar system, particularly in the atmosphere of the Earth. These bounds can be conveniently utilized to test the f(R) models with given functional forms of f(R) and to obtain the constraints on the parameters therein. For demonstration we apply these bounds to several widely considered f(R) models. (H0: Hubble constant)
North American SynchroPhasor Initiative (NASPI) Technical Report...
Office of Environmental Management (EM)
Technology and Renewables Integration North American SynchroPhasor Initiative (NASPI) Technical Report - Synchrophasor Technology and Renewables Integration This technical...
Imagined Islands: American Empire and Identity in the Postcolonial Pacific
Solar, Valerie Chihiro
2010-01-01T23:59:59.000Z
American Cinema. Ed. Manthia Diawara. New York: Routledge,as an interrogating tool. Manthia Diawara claims that “every
EIS-0468: American Centrifuge Plant in Piketon, OH | Department...
Broader source: Energy.gov (indexed) [DOE]
May 20, 2011 EIS-0468: Final Environmental Impact Statement Proposed American Centrifuge Plant in Piketon, Ohio Pike County, Ohio...
Independent Loop Invariants for 2+1 Gravity
R. Loll
1994-08-03T23:59:59.000Z
We identify an explicit set of complete and independent Wilson loop invariants for 2+1 gravity on a three-manifold $M=\\R\\times\\Sigma^g$, with $\\Sigma^g$ a compact oriented Riemann surface of arbitrary genus $g$. In the derivation we make use of a global cross section of the $PSU(1,1)$-principal bundle over Teichm\\"uller space given in terms of Fenchel-Nielsen coordinates.
Particlelike solutions in modified gravity: the Higgs monopole
Sandrine Schlogel; Massimiliano Rinaldi; Francois Staelens; Andre Fuzfa
2014-08-21T23:59:59.000Z
Higgs inflation has received a remarkable attention in the last few years due to its simplicity and predictive power. The key point of this model is the nonminimal coupling to gravity in unitary gauge. As such, this theory is in fact a scalar-tensor modification of gravity that needs to be studied also below the energy scales of inflation. Motivated by this goal, we study in great analytical and numerical detail the static and spherically symmetric solutions of the equations of motion in the presence of standard baryonic matter, called "Higgs monopoles" and presented in 1305.2640. These particlelike solutions may arise naturally in tensor-scalar gravity with mexican hat potential and are the only globally regular asymptotically flat solutions with finite classical energy. In the case when the parameters of the potential are taken to be the ones of the standard model, we find that the deviations from general relativity are extremely small, especially for bodies of astrophysical size and density. This allows to derive a simplified description of the monopole, for which the metric inside the spherical matter distribution can be approximated by the standard metric of general relativity. We study how the properties of these monopoles depend on the strength of the nonminimal coupling to gravity and on the baryonic mass and compactness. An important and original result is the existence of a mechanism of resonant amplification of the Higgs field inside the monopole that comes into play for large nonminimal coupling. We show that this mechanism might degenerate into divergences of the Higgs field that reveal the existence of forbidden combinations of radius and baryonic energy density.
Electric field in 3D gravity with torsion
M. Blagojevi?; B. Cvetkovi?
2008-09-01T23:59:59.000Z
It is shown that in static and spherically symmetric configurations of the system of Maxwell field coupled to 3D gravity with torsion, at least one of the Maxwell field components has to vanish. Restricting our attention to the electric sector of the theory, we find an interesting exact solution, corresponding to the azimuthal electric field. Its geometric structure is to a large extent influenced by the values of two different central charges, associated to the asymptotic AdS structure of spacetime.
Fluid/Gravity Correspondence, Second Order Transport and Gravitational Anomaly
Eugenio Megias; Francisco Pena-Benitez
2013-07-29T23:59:59.000Z
We study the transport properties of a relativistic fluid affected by chiral and gauge-gravitational anomalies. The computation is performed in the framework of the fluid/gravity correspondence for a 5 dim holographic model with Chern-Simons terms in the action. We find new anomalous and non anomalous transport coefficients, as well as new contributions to the existing ones coming from the mixed gauge-gravitational anomaly. Consequences for the shear waves dispersion relation are analyzed.
Dust Static Spherically Symmetric Solution in $f(R)$ Gravity
Muhammad Sharif; Hafiza Rizwana Kausar
2011-02-21T23:59:59.000Z
In this paper, we take dust matter and investigate static spherically symmetric solution of the field equations in metric f(R) gravity. The solution is found with constant Ricci scalar curvature and its energy distribution is evaluated by using Landau-Lifshitz energy-momentum complex. We also discuss the stability condition and constant scalar curvature condition for some specific popular choices of f(R) models in addition to their energy distribution.
Gravity interpretation of the northern Overthrust Belt, Idaho and Wyoming
Silver, Wendy Ilene
1979-01-01T23:59:59.000Z
profiles A-A', B-8', and C-C' within the northern Overthrust Belt and the Green River Basin 45 48 17 Comparison of original structure section (top) and final interpretive structure model (bottom) for profile A-A' across the northern Overthrust Belt... 52 18 Observed and computed gravity values and fina'1 interpretive structure model for profile A-A' across the northern Overthrust Belt 54 19 Comparison of original structure section (top) and final interpretive structure model (bottom...
Tolman mass, generalized surface gravity, and entropy bounds
Abreu, Gabriel
2010-01-01T23:59:59.000Z
In any static spacetime the quasi-local Tolman mass contained within a volume can be reduced to a Gauss-like surface integral involving the flux of a suitably defined generalized surface gravity. By introducing some basic thermodynamics and invoking the Unruh effect one can then develop elementary bounds on the quasi-local entropy that are very similar in spirit to the holographic bound, and closely related to entanglement entropy.
Constraints on massive gravity theory from big bang nucleosynthesis
Lambiase, G., E-mail: lambiase@sa.infn.it [Dipartimento di Fisica 'E. R.Caianiello', Università di Salerno, 84081 Baronissi (Italy)
2012-10-01T23:59:59.000Z
The massive gravity cosmology is studied in the scenario of big bang nucleosynthesis. By making use of current bounds on the deviation from the fractional mass, we derive the constraints on the free parameters of the theory. The cosmological consequences of the model are also analyzed in the framework of the PAMELA experiment, i.e. an excess of positron events, that the conventional cosmology and particle physics cannot explain.
Multipole moments in scalar-tensor theory of gravity
George Pappas; Thomas P. Sotiriou
2015-01-30T23:59:59.000Z
Stationary, asymptotically flat spacetimes in general relativity can be characterized by their multipole moments. The moments have proved to be very useful tools for extracting information about the spacetime from various observables and, more recently, for establishing universalities in the structure of neutron stars. As a first step toward extending these methods beyond general relativity, we develop the formalism that allows one to define and calculate the multipole moments in scalar-tensor theories of gravity.
Dangerous implications of a minimum length in quantum gravity
Cosimo Bambi; Katherine Freese
2008-07-17T23:59:59.000Z
The existence of a minimum length and a generalization of the Heisenberg uncertainty principle seem to be two fundamental ingredients required in any consistent theory of quantum gravity. In this letter we show that they would predict dangerous processes which are phenomenologically unacceptable. For example, long--lived virtual super--Planck mass black holes may lead to rapid proton decay. Possible solutions of this puzzle are briefly discussed.
A Vacuum Solution with Torsion in Higher-Derivative Gravity
Kouzou Nishida
2012-09-02T23:59:59.000Z
In this paper, we provide a vacuum solution with torsion in quadratic Riemann-curvature gravity. Physically, the solution means that vacuum can have a nonzero vacuum field with large torsion. We show that the Einstein-Hilbert action can be derived if we expand the quadratic curvature of the Lagrangian in a torsion-free Riemannian space-time around a nonzero vacuum field. We also show that the cosmological constant caused by a nonzero vacuum field is equal to zero.
Galaxy Clustering in 3D and Modified Gravity Theories
Dipak Munshi; Geraint Pratten; Patrick Valageas; Peter Coles; Philippe Brax
2015-08-03T23:59:59.000Z
We study Modified Gravity (MG) theories by modelling the redshifted matter power spectrum in a spherical Fourier-Bessel (sFB) basis. We use a fully non-linear description of the real-space matter power-spectrum and include the lowest-order redshift-space correction (Kaiser effect), taking into account some additional non-linear contributions. Ignoring relativistic corrections, which are not expected to play an important role for a shallow survey, we analyse two different modified gravity scenarios, namely the generalised Dilaton scalar-tensor theories and the $f({R})$ models in the large curvature regime. We compute the 3D power spectrum ${\\cal C}^s_{\\ell}(k_1,k_2)$ for various such MG theories with and without redshift space distortions, assuming precise knowledge of background cosmological parameters. Using an all-sky spectroscopic survey with Gaussian selection function $\\varphi(r)\\propto \\exp(-{r^2 / r^2_0})$, $r_0 = 150 \\, h^{-1} \\, {\\textrm{Mpc}}$, and number density of galaxies $\\bar {\\textrm{N}} =10^{-4}\\;{\\textrm{Mpc}}^{-3}$, we use a $\\chi^2$ analysis, and find that the lower-order $(\\ell \\leq 25)$ multipoles of ${\\cal C}^s_\\ell(k,k')$ (with radial modes restricted to $k 25$ modes can further reduce the error bars and thus in principle make cosmological gravity constraints competitive with solar system tests. However this will require an accurate modelling of non-linear redshift space distortions. Using a tomographic $\\beta(a)$-$m(a)$ parameterization we also derive constraints on specific parameters describing the Dilaton models of modified gravity.