Category:Airborne Gravity Survey | Open Energy Information
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Investigating High Field Gravity using Astrophysical Techniques
Bloom, Elliott D.; /SLAC
2008-02-01
The purpose of these lectures is to introduce particle physicists to astrophysical techniques. These techniques can help us understand certain phenomena important to particle physics that are currently impossible to address using standard particle physics experimental techniques. As the subject matter is vast, compromises are necessary in order to convey the central ideas to the reader. Many general references are included for those who want to learn more. The paragraphs below elaborate on the structure of these lectures. I hope this discussion will clarify my motivation and make the lectures easier to follow. The lectures begin with a brief review of more theoretical ideas. First, elements of general relativity are reviewed, concentrating on those aspects that are needed to understand compact stellar objects (white dwarf stars, neutron stars, and black holes). I then review the equations of state of these objects, concentrating on the simplest standard models from astrophysics. After these mathematical preliminaries, Sec. 2(c) discusses 'The End State of Stars'. Most of this section also uses the simplest standard models. However, as these lectures are for particle physicists, I also discuss some of the more recent approaches to the equation of state of very dense compact objects. These particle-physics-motivated equations of state can dramatically change how we view the formation of black holes. Section 3 focuses on the properties of the objects that we want to characterize and measure. X-ray binary systems and Active Galactic Nuclei (AGN) are stressed because the lectures center on understanding very dense stellar objects, black hole candidates (BHCs), and their accompanying high gravitational fields. The use of x-ray timing and gamma-ray experiments is also introduced in this section. Sections 4 and 5 review information from x-ray and gamma-ray experiments. These sections also discuss the current state of the art in x-ray and gamma-ray satellite experiments and plans for future experiments.
Centinello, Frank Joseph, III
2015-01-01
This dissertation presents improvements made on position estimation techniques applied to seismology, airborne gravimetry and planetary gravity recovery. In Chapters 2 and 3, a smoothed ionospheric model computed using GPS ...
Lebach, D. E.; Ratner, M. I.; Shapiro, I. I.; Bartel, N.; Bietenholz, M. F.; Lederman, J. I.; Ransom, R. R.; Campbell, R. M.; Gordon, D.
2012-07-01
When very long baseline interferometry (VLBI) observations are used to determine the position or motion of a radio source relative to reference sources nearby on the sky, the astrometric information is usually obtained via (1) phase-referenced maps or (2) parametric model fits to measured fringe phases or multiband delays. In this paper, we describe a 'merged' analysis technique which combines some of the most important advantages of these other two approaches. In particular, our merged technique combines the superior model-correction capabilities of parametric model fits with the ability of phase-referenced maps to yield astrometric measurements of sources that are too weak to be used in parametric model fits. We compare the results from this merged technique with the results from phase-referenced maps and from parametric model fits in the analysis of astrometric VLBI observations of the radio-bright star IM Pegasi (HR 8703) and the radio source B2252+172 nearby on the sky. In these studies we use central-core components of radio sources 3C 454.3 and B2250+194 as our positional references. We obtain astrometric results for IM Peg with our merged technique even when the source is too weak to be used in parametric model fits, and we find that our merged technique yields astrometric results superior to the phase-referenced mapping technique. We used our merged technique to estimate the proper motion and other astrometric parameters of IM Peg in support of the NASA/Stanford Gravity Probe B mission.
ABSTRACT A new airborne formaldehyde measurement technique was developed and deployed on board is based on scrubbing gaseous formaldehyde into an aqueous solution containing 2,4-dinitrophenylhydrazine. The formaldehyde concentration measured in the boundary layer air over the Phoenix basin ranged from ca. 1 to 4
Barnhart, Kevin Scott
2013-10-01
We proposed to customize emerging in situ geophysical monitoring technology to generate time-series data during sporadic rain events in a semi-arid region. Electrodes were to be connected to wireless %5Cnodes%22 which can be left in the eld for many months. Embedded software would then increase sampling frequency during periods of rainfall. We hypothesized that this contrast between no-volume ow in karst passageways dur- ing dry periods and partial- or saturated-volume ow during a rain event is detectable by these Wireless Sensor Network (WSN) geophysical nodes, we call this a Wireless Resistivity Network (WRN). The development of new methodologies to characterize semi-arid karst hydrology is intended to augment Sandia National Laboratorys mission to lead e orts in energy technologies, waste disposal and climate security by helping to identify safe and secure regions and those that are at risk. Development and initial eld testing identi ed technological barriers to using WRNs for identifying semi-arid karst, exposing R&D which can be targeted in the future. Gravity, seismic, and resis- tivity surveys elucidated how each technique might e ectively be used to characterize semi-arid karst. This research brings to light the importance and challenges with char- acterizing semi-arid karst through a multi-method geophysical study. As there have been very few studies with this emphasis, this study has expanded the body of practical experience needed to protect the nations water and energy security interests.
Gravity Waves from Rotating Neutron Stars and Evaluation of Fast Chirp Transform Techniques
Tod E. Strohmayer
2001-09-28
X-ray observations suggest that neutron stars in low mass X-ray binaries (LMXB) are rotating with frequencies from 300 - 600 Hz. These spin rates are significantly less than the break-up rates for essentially all realistic neutron star equations of state, suggesting that some process may limit the spin frequencies of accreting neutron stars to this range. If the accretion induced spin up torque is in equilibrium with gravitational radiation losses, these objects could be interesting sources of gravity waves. I present a brief summary of current measurements of neutron star spins in LMXBs based on the observations of high-Q oscillations during thermonuclear bursts (so called ``burst oscillations''). Further measurements of neutron star spins will be important in exploring the gravitational radiation hypothesis in more detail. To this end I also present a study of fast chirp transform (FCT) techniques as described by Jenet & Prince (2000) in the context of searching for the chirping signals observed during X-ray bursts.
A Novel Two-Step Laser Ranging Technique for a Precision Test of the Theory of Gravity
Penanen, K; Penanen, Konstantin; Chui, Talso
2004-01-01
All powered spacecraft experience residual systematic acceleration due to anisotropy of the thermal radiation pressure and fuel leakage. The residual acceleration limits the accuracy of any test of gravity that relies on the precise determination of the spacecraft trajectory. We describe a novel two-step laser ranging technique, which largely eliminates the effects of non-gravity acceleration sources and enables celestial mechanics checks with unprecedented precision. A passive proof mass is released from the mother spacecraft on a solar system exploration mission. Retro-reflectors attached to the proof mass allow its relative position to the spacecraft to be determined using optical ranging techniques. Meanwhile, the position of the spacecraft relative to the Earth is determined by ranging with a laser transponder. The vector sum of the two is the position, relative to the Earth, of the proof mass, the measurement of which is not affected by the residual accelerations of the mother spacecraft. We also descri...
A Novel Two-Step Laser Ranging Technique for a Precision Test of the Theory of Gravity
Konstantin Penanen; Talso Chui
2004-06-04
All powered spacecraft experience residual systematic acceleration due to anisotropy of the thermal radiation pressure and fuel leakage. The residual acceleration limits the accuracy of any test of gravity that relies on the precise determination of the spacecraft trajectory. We describe a novel two-step laser ranging technique, which largely eliminates the effects of non-gravity acceleration sources and enables celestial mechanics checks with unprecedented precision. A passive proof mass is released from the mother spacecraft on a solar system exploration mission. Retro-reflectors attached to the proof mass allow its relative position to the spacecraft to be determined using optical ranging techniques. Meanwhile, the position of the spacecraft relative to the Earth is determined by ranging with a laser transponder. The vector sum of the two is the position, relative to the Earth, of the proof mass, the measurement of which is not affected by the residual accelerations of the mother spacecraft. We also describe the mission concept of the Dark Matter Explorers (DMX), which will demonstrate this technology and will use it to test the hypothesis that dark matter congregates around the sun. This hypothesis implies a small apparent deviation from the inverse square law of gravity, which can be detected by a sensitive experiment. We expect to achieve an acceleration resolution of $\\sim 10^{-14} m/s^2$. DMX will also be sensitive to acceleration towards the galactic center, which has a value of $\\sim 10^{-10} m/s^2$. Since dark matter dominates the galactic acceleration, DMX can also test whether dark matter obeys the equivalence principle to a level of 100 ppm by ranging to several proof masses of different composition from the mother spacecraft.
Airborne Gravity Survey | Open Energy Information
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Geophex Airborne Unmanned Survey System
Won, I.L.; Keiswetter, D.
1995-12-31
Ground-based surveys place personnel at risk due to the proximity of buried unexploded ordnance (UXO) items or by exposure to radioactive materials and hazardous chemicals. The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide stand-off capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected. The Geophex Airborne Unmanned Survey System (GAUSS) is designed to detect and locate small-scale anomalies at hazardous sites using magnetic and electromagnetic survey techniques. The system consists of a remotely-piloted, radio-controlled, model helicopter (RCH) with flight computer, light-weight geophysical sensors, an electronic positioning system, a data telemetry system, and a computer base-station. The report describes GAUSS and its test results.
Airborne wireless communication systems, airborne communication methods, and communication methods
Deaton, Juan D. (Menan, ID); Schmitt, Michael J. (Idaho Falls, ID); Jones, Warren F. (Idaho Falls, ID)
2011-12-13
An airborne wireless communication system includes circuitry configured to access information describing a configuration of a terrestrial wireless communication base station that has become disabled. The terrestrial base station is configured to implement wireless communication between wireless devices located within a geographical area and a network when the terrestrial base station is not disabled. The circuitry is further configured, based on the information, to configure the airborne station to have the configuration of the terrestrial base station. An airborne communication method includes answering a 911 call from a terrestrial cellular wireless phone using an airborne wireless communication system.
Airborne Pollution In urban environments
Broday, David
Airborne Pollution In urban environments What are the real health effects of urban pollution Air Pollution- relevant Human Exposure in Urban Environments" Funded under the "City of Tomorrow" programme of the European Union: Contract number EVK4-CT-2002-00090 URBAN POLLUTION Airborne pollutants
Modeling for Airborne Contamination
F.R. Faillace; Y. Yuan
2000-08-31
The objective of Modeling for Airborne Contamination (referred to from now on as ''this report'') is to provide a documented methodology, along with supporting information, for estimating the release, transport, and assessment of dose to workers from airborne radioactive contaminants within the Monitored Geologic Repository (MGR) subsurface during the pre-closure period. Specifically, this report provides engineers and scientists with methodologies for estimating how concentrations of contaminants might be distributed in the air and on the drift surfaces if released from waste packages inside the repository. This report also provides dose conversion factors for inhalation, air submersion, and ground exposure pathways used to derive doses to potentially exposed subsurface workers. The scope of this report is limited to radiological contaminants (particulate, volatile and gaseous) resulting from waste package leaks (if any) and surface contamination and their transport processes. Neutron activation of air, dust in the air and the rock walls of the drift during the preclosure time is not considered within the scope of this report. Any neutrons causing such activation are not themselves considered to be ''contaminants'' released from the waste package. This report: (1) Documents mathematical models and model parameters for evaluating airborne contaminant transport within the MGR subsurface; and (2) Provides tables of dose conversion factors for inhalation, air submersion, and ground exposure pathways for important radionuclides. The dose conversion factors for air submersion and ground exposure pathways are further limited to drift diameters of 7.62 m and 5.5 m, corresponding to the main and emplacement drifts, respectively. If the final repository design significantly deviates from these drift dimensions, the results in this report may require revision. The dose conversion factors are further derived by using concrete of sufficient thickness to simulate the drift walls. The gamma-ray scattering properties of concrete are sufficiently similar to those of the host rock and proposed insert material; use of concrete will have no significant impact on the conclusions. The information in this report is presented primarily for use in performing pre-closure radiological safety evaluations of radiological contaminants, but it may also be used to develop strategies for contaminant leak detection and monitoring in the MGR. Included in this report are the methods for determining the source terms and release fractions, and mathematical models and model parameters for contaminant transport and distribution within the repository. Various particle behavior mechanisms that affect the transport of contaminant are included. These particle behavior mechanisms include diffusion, settling, resuspension, agglomeration and other deposition mechanisms.
Airborne agent concentration analysis
Gelbard, Fred
2004-02-03
A method and system for inferring airborne contaminant concentrations in rooms without contaminant sensors, based on data collected by contaminant sensors in other rooms of a building, using known airflow interconnectivity data. The method solves a least squares problem that minimizes the difference between measured and predicted contaminant sensor concentrations with respect to an unknown contaminant release time. Solutions are constrained to providing non-negative initial contaminant concentrations in all rooms. The method can be used to identify a near-optimal distribution of sensors within the building, when then number of available sensors is less than the total number of rooms. This is achieved by having a system-sensor matrix that is non-singular, and by selecting that distribution which yields the lowest condition number of all the distributions considered. The method can predict one or more contaminant initial release points from the collected data.
2010-09-01
Broad Funding Opportunity Announcement Project: Makani Power is developing an Airborne Wind Turbine (AWT) that eliminates 90% of the mass of a conventional wind turbine and accesses a stronger, more consistent wind at altitudes of near 1,000 feet. At these altitudes, 85% of the country can offer viable wind resources compared to only 15% accessible with current technology. Additionally, the Makani Power wing can be economically deployed in deep offshore waters, opening up a resource which is 4 times greater than the entire U.S. electrical generation capacity. Makani Power has demonstrated the core technology, including autonomous launch, land, and power generation with an 8 meter wingspan, 20 kW prototype. At commercial scale, Makani Power aims to develop a 600 kW, 28 meter wingspan product capable of delivering energy at an unsubsidized cost competitive with coal, the current benchmark for low-cost power.
Gravity Techniques | Open Energy Information
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Massive gravity from bimetric gravity
Baccetti, Valentina; Visser, Matt
2012-01-01
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.
Liouville gravity from Einstein gravity
D. Grumiller; R. Jackiw
2007-12-28
We show that Liouville gravity arises as the limit of pure Einstein gravity in 2+epsilon dimensions as epsilon goes to zero, provided Newton's constant scales with epsilon. Our procedure - spherical reduction, dualization, limit, dualizing back - passes several consistency tests: geometric properties, interactions with matter and the Bekenstein-Hawking entropy are as expected from Einstein gravity.
Signal processing for airborne bistatic radar
Ong, Kian P
The major problem encountered by an airborne bistatic radar is the suppression of bistatic clutter. Unlike clutter echoes for a sidelooking airborne monostatic radar, bistatic clutter echoes are range dependent. Using ...
Ng, Kit-Tong
1994-01-01
Digital image processing technique and fuzzy logic approach are used to identify forest areas infested with Southern Pine Beetle, SPB, using normal color airborne imageries in this research. This research will be used as a front end of a larger...
Einstein Gravity from Conformal Gravity
Juan Maldacena
2011-06-09
We show that that four dimensional conformal gravity plus a simple Neumann boundary condition can be used to get the semiclassical (or tree level) wavefunction of the universe of four dimensional asymptotically de-Sitter or Euclidean anti-de Sitter spacetimes. This simple Neumann boundary condition selects the Einstein solution out of the more numerous solutions of conformal gravity. It thus removes the ghosts of conformal gravity from this computation. In the case of a five dimensional pure gravity theory with a positive cosmological constant we show that the late time superhorizon tree level probability measure, $|\\Psi [ g ]|^2$, for its four dimensional spatial slices is given by the action of Euclidean four dimensional conformal gravity.
Lujan, Richard E. (Santa Fe, NM)
2001-01-01
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.
Reduced models for quantum gravity
T. Thiemann
1999-10-04
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.
Airborne Data Processing and Analysis Software Package
Delene, David J.
Airborne Data Processing and Analysis Software Package David J. Delene1 1 Department of Atmospheric-9006 Correspondance Email: delene@aero.und.edu Software Article submitted to Earth Science Informatics on 28 December Measurement, Open Source Scientific Software, Airborne Measurements, Research Aircraft 1 #12;Abstract
MSIV leakage airborne iodine transport
Cline, J.E. (Cline Associates Inc., Rockville, MD (United States))
1993-01-01
Gaseous iodine deposits on surfaces exposed to vapors. Basic chemical and physical principles predict this behavior, and several laboratory and in-plant measurements demonstrate the characteristic. An empirical model was developed that describes the deposition, resuspension, and transformation of airborne radioiodine molecular species as a stream containing these forms moves along its pathway. The model uses a data base of measured values of deposition and resuspension rates in its application and describes the conversion of the more reactive inorganic iodine species I[sub 2] to the less reactive organic species CH[sub 3]I as the iodine deposits and resuspends along the path. It also considers radioactive decay and chemical surface bonding during residence on surfaces. For the 8-day [sup 131]I, decay during the airborne portion of the transport is negligible. Verification of the model included measurement tests of long gaseous-activity sampling lines of different diameters, operated at different flow rates and stream temperatures. The model was applied to the streams at a boiling water reactor nuclear power plant to describe the transport through leaking main steam isolation valves (MSIVs), following a loss-of-coolant accident.
Airborne measured analytic signal for UXO detection
Gamey, T.J.; Holladay, J.S. [Aerodat Inc., Mississauga, Ontario (Canada); Mahler, R. [Industrieanlagen Betriebsgesellschaft, Deutschland (Australia)
1997-10-01
The Altmark Tank Training Range north of Haldensleben, Germany has been in operation since WWI. Weapons training and testing has included cavalry, cannon, small arms, rail guns, and tank battalions. Current plans are to convert the area to a fully digital combat training facility. Instead of using blank or dummy ordnance, hits will be registered with lasers and computers. Before this can happen, the 25,000 ha must be cleared of old debris. In support of this cleanup operation, Aerodat Inc., in conjunction with IABG of Germany, demonstrated a new high resolution magnetic survey technique involving the measurement of 3-component magnetic gradient data. The survey was conducted in May 1996, and covered 500 ha in two blocks. The nominal line spacing was 10 m, and the average sensor altitude was 7 m. The geologic column consisted of sands over a sedimentary basin. Topographic relief was generally flat with approximately 3 m rolling dunes and occasional man-made features such as fox holes, bunkers, tank traps and reviewing stands. Trees were sparse and short (2-3 metres) due to frequent burn off and tank activity. As such, this site was nearly ideal for low altitude airborne surveying.
Is nonrelativistic gravity possible?
Kocharyan, A. A.
2009-07-15
We study nonrelativistic gravity using the Hamiltonian formalism. For the dynamics of general relativity (relativistic gravity) the formalism is well known and called the Arnowitt-Deser-Misner (ADM) formalism. We show that if the lapse function is constrained correctly, then nonrelativistic gravity is described by a consistent Hamiltonian system. Surprisingly, nonrelativistic gravity can have solutions identical to relativistic gravity ones. In particular, (anti-)de Sitter black holes of Einstein gravity and IR limit of Horava gravity are locally identical.
B. L. Hu
1999-02-22
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.
Chemistry of airborne particles from metallurgical processing
Jenkins, Neil Travis, 1973-
2003-01-01
Airborne particles fall into one of three size ranges. The nucleation range consists of nanoparticles created from vapor atom collisions. The decisive parameter for particle size and composition is the supercooling of the ...
Principles for Sampling Airborne Radioactivity from Stacks
Glissmeyer, John A.
2010-10-18
This book chapter describes the special processes involved in sampling the airborne effluents from nuclear faciities. The title of the book is Radioactive Air Sampling Methods. The abstract for this chapter was cleared as PNNL-SA-45941.
Thomas Rauch
2006-07-11
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.
Hanson, Andrew J.
2011-01-01
more restrictive context of Einstein's theory of gravity.6782 TORSION AND QUANTUM GRAVITY Andrevr J, Him son Lawrencetorsion in conventional gravity cou~d in fact be dynamicaL A
Hang, Alice Thanh
2009-01-01
The front speed of intrusive gravity currents. J. FluidP.F. Linden. Intrusive gravity currents. J. Fluid Mechanics,of mesoscale variability of gravity waves. Part II: Frontal,
Airborne electromagnetic surveys as a reconnaissance technique for
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Active airborne contamination control using electrophoresis
Veatch, B.D.
1994-06-01
In spite of our best efforts, radioactive airborne contamination continues to be a formidable problem at many of the Department of Energy (DOE) weapons complex sites. For workers that must enter areas with high levels of airborne contamination, personnel protective equipment (PPE) can become highly restrictive, greatly diminishing productivity. Rather than require even more restrictive PPE for personnel in some situations, the Rocky Flats Plant (RFP) is actively researching and developing methods to aggressively combat airborne contamination hazards using electrophoretic technology. With appropriate equipment, airborne particulates can be effectively removed and collected for disposal in one simple process. The equipment needed to implement electrophoresis is relatively inexpensive, highly reliable, and very compact. Once airborne contamination levels are reduced, less PPE is required and a significant cost savings may be realized through decreased waste and maximized productivity. Preliminary ``cold,`` or non-radioactive, testing results at the RFP have shown the technology to be effective on a reasonable scale, with several potential benefits and an abundance of applications.
Micro-Electron Spin Resonance for Airborne Soot Measurement
Broader source: Energy.gov [DOE]
A real-time method for airborne soot concentration measurement using a miniaturized electron spin resonance sensor is presented.
Sandia Multispectral Airborne Lidar for UAV Deployment
Daniels, J.W.; Hargis,Jr. P.J.; Henson, T.D.; Jordan, J.D.; Lang, A.R.; Schmitt, R.L.
1998-10-23
Sandia National Laboratories has initiated the development of an airborne system for W laser remote sensing measurements. System applications include the detection of effluents associated with the proliferation of weapons of mass destruction and the detection of biological weapon aerosols. This paper discusses the status of the conceptual design development and plans for both the airborne payload (pointing and tracking, laser transmitter, and telescope receiver) and the Altus unmanned aerospace vehicle platform. Hardware design constraints necessary to maintain system weight, power, and volume limitations of the flight platform are identified.
Category: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 QA:QA J-E-1 SECTION J APPENDIX ECoopButte County,Camilla, Georgia:Geothermal Regulatory Roadmap Sections JumpKSGravity
Chiral Gravity, Log Gravity and Extremal CFT
Alexander Maloney; Wei Song; Andrew Strominger
2009-03-26
We show that the linearization of all exact solutions of classical chiral gravity around the AdS3 vacuum have positive energy. Non-chiral and negative-energy solutions of the linearized equations are infrared divergent at second order, and so are removed from the spectrum. In other words, chirality is confined and the equations of motion have linearization instabilities. We prove that the only stationary, axially symmetric solutions of chiral gravity are BTZ black holes, which have positive energy. It is further shown that classical log gravity-- the theory with logarithmically relaxed boundary conditions --has finite asymptotic symmetry generators but is not chiral and hence may be dual at the quantum level to a logarithmic CFT. Moreover we show that log gravity contains chiral gravity within it as a decoupled charge superselection sector. We normally evaluate the Euclidean sum over geometries of chiral gravity and show that it gives precisely the holomorphic extremal CFT partition function. The modular invariance and integrality of the expansion coefficients of this partition function are consistent with the existence of an exact quantum theory of chiral gravity. We argue that the problem of quantizing chiral gravity is the holographic dual of the problem of constructing an extremal CFT, while quantizing log gravity is dual to the problem of constructing a logarithmic extremal CFT.
Aris, John P.
Sterile Technique Sterile (aseptic) technique is essential to avoiding contamination in yeast experiments have increased risk for contamination because the same samples / tubes are opened repeatedly over containers are open. Keep air movement to a minimum to limit airborne contamination. 6. Do not pour sterile
Towards noncommutative gravity
D. V. Vassilevich
2009-02-17
In this short article accessible for non-experts I discuss possible ways of constructing a non-commutative gravity paying special attention to possibilities of realizing the full diffeomorphism symmetry and to relations with 2D gravities.
Rong-Jia Yang
2014-09-11
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.
Karim Noui
2010-03-31
We tackle the question of motion in Quantum Gravity: what does motion mean at the Planck scale? Although we are still far from a complete answer we consider here a toy model in which the problem can be formulated and resolved precisely. The setting of the toy model is three dimensional Euclidean gravity. Before studying the model in detail, we argue that Loop Quantum Gravity may provide a very useful approach when discussing the question of motion in Quantum Gravity.
Terrestrial Gravity Fluctuations
Jan Harms
2015-07-21
The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article.
Stephen Hawking Quantum Gravity
Visser, Matt
Stephen Hawking and Quantum Gravity Matt Visser Physics Department Washington University Saint Louis USA Science Saturdays 4 Nov 2000 #12; Stephen Hawking and Quantum Gravity Abstract: Through research, Stephen Hawking has captured a place in the popular imagina- tion. Quantum gravity in its various
Quantum Physics Einstein's Gravity
Visser, Matt
Quantum Physics confronts Einstein's Gravity Matt Visser Physics Department Washington University Saint Louis USA Science Saturdays 13 October 2001 #12; Quantum Physics confronts Einstein's Gravity and with Einstein's theory of gravity (the general relativity) is still the single biggest theoretical problem
Analyzing Options for Airborne Emergency Wireless Communications
Michael Schmitt; Juan Deaton; Curt Papke; Shane Cherry
2008-03-01
In the event of large-scale natural or manmade catastrophic events, access to reliable and enduring commercial communication systems is critical. Hurricane Katrina provided a recent example of the need to ensure communications during a national emergency. To ensure that communication demands are met during these critical times, Idaho National Laboratory (INL) under the guidance of United States Strategic Command has studied infrastructure issues, concerns, and vulnerabilities associated with an airborne wireless communications capability. Such a capability could provide emergency wireless communications until public/commercial nodes can be systematically restored. This report focuses on the airborne cellular restoration concept; analyzing basic infrastructure requirements; identifying related infrastructure issues, concerns, and vulnerabilities and offers recommended solutions.
MAPPING FELDSPARS WITH AIRBORNE HYPERSPECTRAL SEBASS IMAGERY
OSU DEAN RILEY AERO / SPECTIR MARK VAN DER MEIJDE ITC-UT FREEK VAN DER MEER ITC-UT #12;MINERAL MODES://www.lpi.usra.edu/science/kirkland/Mesa/text.html Data courtesy Dr. Dean Riley, Aero.org APPLICATION TO AIRBORNE HYPERSPECTRAL IMAGE DATA AEROSPACE HECKER ITC-UT JOHN DILLES OSU DEAN RILEY AERO / SPECTIR MARK VAN DER MEIJDE ITC-UT FREEK VAN DER MEER ITC
Airborne Tactical Free-Electron Laser
Roy Whitney; George Neil
2007-02-01
The goal of 100 kilowatts (kW) of directed energy from an airborne tactical platform has proved challenging due to the size and weight of most of the options that have been considered. However, recent advances in Free-Electron Lasers appear to offer a solution along with significant tactical advantages: a nearly unlimited magazine, time structures for periods from milliseconds to hours, radar like functionality, and the choice of the wavelength of light that best meets mission requirements. For an Airborne Tactical Free-Electron Laser (ATFEL) on a platforms such as a Lockheed C-130J-30 and airships, the two most challenging requirements, weight and size, can be met by generating the light at a higher harmonic, aggressively managing magnet weights, managing cryogenic heat loads using recent SRF R&D results, and using FEL super compact design concepts that greatly reduce the number of components. The initial R&D roadmap for achieving an ATFEL is provided in this paper. Performing this R&D is expected to further reduce the weight, size and power requirements for the FELs the Navy is currently developing for shipboard applications, as well as providing performance enhancements for the strategic airborne MW class FELs. The 100 kW ATFEL with its tactical advantages may prove sufficiently attractive for early advancement in the queue of deployed FELs.
Quantization of Emergent Gravity
Hyun Seok Yang
2014-12-24
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.
Airborne Multisensor Pod System (AMPS) data management overview
Wiberg, J.D.; Blough, D.K.; Daugherty, W.R.; Hucks, J.A.; Gerhardstein, L.H.; Meitzler, W.D.; Melton, R.B.; Shoemaker, S.V.
1994-09-01
An overview of the Data Management Plan for the Airborne Multisensor Pod System (AMPS) pro-grain is provided in this document. The Pacific Northwest Laboratory (PNL) has been assigned the responsibility of data management for the program, which includes defining procedures for data management and data quality assessment. Data management is defined as the process of planning, acquiring, organizing, qualifying and disseminating data. The AMPS program was established by the U.S. Department of Energy (DOE), Office of Arms Control and Non-Proliferation (DOE/AN) and is integrated into the overall DOE AN-10.1 technology development program. Sensors used for collecting the data were developed under the on-site inspection, effluence analysis, and standoff sensor program, the AMPS program interacts with other technology programs of DOE/NN-20. This research will be conducted by both government and private industry. AMPS is a research and development program, and it is not intended for operational deployment, although the sensors and techniques developed could be used in follow-on operational systems. For a complete description of the AMPS program, see {open_quotes}Airborne Multisensor Pod System (AMPS) Program Plan{close_quotes}. The primary purpose of the AMPS is to collect high-quality multisensor data to be used in data fusion research to reduce interpretation problems associated with data overload and to derive better information than can be derived from any single sensor. To collect the data for the program, three wing-mounted pods containing instruments with sensors for collecting data will be flight certified on a U.S. Navy RP-3A aircraft. Secondary objectives of the AMPS program are sensor development and technology demonstration. Pod system integrators and instrument developers will be interested in the performance of their deployed sensors and their supporting data acquisition equipment.
The Airborne Metagenome in an Indoor Urban Environment
Tringe, Susannah
2009-01-01
independent approaches to microbes harvested from the air ofthat the indoor air microbes are not random transients fromhealth policies. Airborne microbes are often attached to
ccpi-airborne_r2 | netl.doe.gov
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
COMMERCIAL SCALE DEMONSTRATION PROGRAM MUSTANG CLEAN ENERGY, LLC, a subsidiary of PEABODY ENERGY ST. LOUIS, MISSOURI PROJECT FACT SHEET Airborne Process(tm) Commercial Scale...
A multivariate spatial interpolation of airborne -ray data using the geological constraints
Roma "La Sapienza", Universitŕ di
A multivariate spatial interpolation of airborne -ray data using the geological constraints Enrico: Multivariate analysis Airborne -ray spectrometry Collocated cokriging interpolator Elba Island Natural (Italy) obtained with a multivariate spatial interpolation of airborne -ray data using the constraints
A Distinction Technique Between Volcanic And Tectonic Depression...
Distinction Technique Between Volcanic And Tectonic Depression Structures Based On The Restoration Modeling Of Gravity Anomaly- A Case Study Of The Hohi Volcanic Zone, Central...
F. Henry-Couannier; A. Tilquin; C. Tao; A. Ealet
2007-10-24
The previous version of this article was a first attempt to confront the Dark Gravity theory to cosmological data. However, more recent developments lead to the conclusion that the cosmological principle is probably not valid in Dark Gravity so that this kind of analysis is at best very premature. A more recent and living review of the Dark Gravity theory can be found in gr-qc/0610079
Airborne Electromagnetic Survey | 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 QA:QA J-E-1 SECTION J APPENDIX ECoop IncIowaWisconsin: Energy ResourcesAir Quality Jump to: navigation,Airborne
Felix M. Lev
2010-05-16
We consider a possibility that gravity is not an interaction but a manifestation of a symmetry based on a Galois field.
Automatic Extraction of Cartographic Information from Airborne Interferometric SAR Data
Mayer, Helmut A.
Automatic Extraction of Cartographic Information from Airborne Interferometric SAR Data Reinhold cartographic feature extraction by the airborne AeS--1 instrument is presented. We extract regions corresponding to cartographic features for the classes built--up area, forest, water and open area. Water
Emergent gravity requires kinematic nonlocality
Marolf, D
2015-01-01
Saueressig, Quantum Einstein Gravity, New J.Phys. 14 (2012)T. Matsuki, and H. Terazawa, Gravity and Electromagnetism asat a lattice formulation of gravity, . http://cds.cern.ch/
Quantum gravity on the lattice
Hamber, Herbert W.
2009-01-01
the Conference Quantum Gravity: Challenges and Perspectives.divergences in quantum gravity. In: Hawking, S.W. , Israel,f ) V n?1 ( f ) = Quantum gravity on the lattice Similarly,
for Gravity, Electrical, and Magnetics, Colorado School of Mines, Golden, Colorado SUMMARY Recently3D joint inversion of gradient and total-field magnetic data Kristofer Davis and Yaoguo Li, Center and demonstrate it with a synthetic and field example. INTRODUCTION Airborne magnetic gradiometry data
Asthmatic responses to airborne acid aerosols
Ostro, B.D.; Lipsett, M.J.; Wiener, M.B.; Selner, J.C. )
1991-06-01
Controlled exposure studies suggest that asthmatics may be more sensitive to the respiratory effects of acidic aerosols than individuals without asthma. This study investigates whether acidic aerosols and other air pollutants are associated with respiratory symptoms in free-living asthmatics. Daily concentrations of hydrogen ion (H+), nitric acid, fine particulates, sulfates and nitrates were obtained during an intensive air monitoring effort in Denver, Colorado, in the winter of 1987-88. A panel of 207 asthmatics recorded respiratory symptoms, frequency of medication use, and related information in daily diaries. We used a multiple regression time-series model to analyze which air pollutants, if any, were associated with health outcomes reported by study participants. Airborne H+ was found to be significantly associated with several indicators of asthma status, including moderate or severe cough and shortness of breath. Cough was also associated with fine particulates, and shortness of breath with sulfates. Incorporating the participants' time spent outside and exercise intensity into the daily measure of exposure strengthened the association between these pollutants and asthmatic symptoms. Nitric acid and nitrates were not significantly associated with any respiratory symptom analyzed. In this population of asthmatics, several outdoor air pollutants, particularly airborne acidity, were associated with daily respiratory symptoms.
Yu, Qian
with the aid of ancillary topographic data. Image objects as minimum classification units were generatedAbstract In this paper, we evaluate the capability of the high spatial resolution airborne Digital Airborne Imaging System (DAIS) imagery for detailed vegetation classification at the alliance level
Topics in Nonsupersymmetric Scattering Amplitudes in Gauge and Gravity Theories
Nohle, Joshua David
2015-01-01
Gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Ultraviolet Properties of Gravity . . . . . . .Kinematics Duality and Gravity as a Double Copy of Yang-
Use of airborne laser scanning to characterise land degradation processes the Dead Sea as
Marco, Shmuel "Shmulik"
. Keywords: Airborne laser scanning, Geomorphology, Dead Sea, Land degradation, Channel incision, Sinkholes
Probability around the Quantum Gravity. Part 1: Planar Pure Gravity
Probability around the Quantum Gravity. Part 1: Planar Pure Gravity V.A.Malyshev \\Lambda September 17, 1998 Abstract In this paper we study stochastic dynamics which leaves quantum gravity equilibrium science and biology. At the same time the paper can serve an intro duction to quantum gravity
CALIOPE and TAISIR airborne experiment platform
Chocol, C.J.
1994-07-01
Between 1950 and 1970, scientific ballooning achieved many new objectives and made a substantial contribution to understanding near-earth and space environments. In 1986, the Lawrence Livermore National Laboratory (LLNL) began development of ballooning technology capable of addressing issues associated with precision tracking of ballistic missiles. In 1993, the Radar Ocean Imaging Project identified the need for a low altitude (1 km) airborne platform for its Radar system. These two technologies and experience base have been merged with the acquisition of government surplus Aerostats by Lawrence Livermore National Laboratory. The CALIOPE and TAISIR Programs can benefit directly from this technology by using the Aerostat as an experiment platform for measurements of the spill facility at NTS.
Zygmunt Lalak; Stefan Pokorski; Krzysztof Turzynski
2008-08-18
We investigate O'Raifeartaigh-type models for F-term supersymmetry breaking in gauge mediation scenarios in the presence of gravity. It is pointed out that the vacuum structure of those models is such that in metastable vacua gravity mediation contribution to scalar masses is always suppressed to the level below 1 percent, almost sufficient for avoiding FCNC problem. Close to that limit, gravitino mass can be in the range 10-100 GeV, opening several interesting possibilities for gauge mediation models, including Giudice-Masiero mechanism for mu and Bmu generation. Gravity sector can include stabilized moduli.
Shan Gao
2011-07-16
It is argued that the existence of a minimum size of spacetime may imply the fundamental existence of gravity as a geometric property of spacetime described by general relativity.
Francis J. M. Farley
2015-08-14
In the muon storage rings the muons are subject to a very large radial acceleration. The equivalence principle implies a large gravity force. It has no effect on the muon lifetime.
Exercise in artificial gravity
Edmonds, Jessica Leigh
2005-01-01
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 ...
Human Occupancy as a Source of Indoor Airborne Bacteria
Hospodsky, Denina
Exposure to specific airborne bacteria indoors is linked to infectious and noninfectious adverse health outcomes. However, the sources and origins of bacteria suspended in indoor air are not well understood. This study ...
Epidemiology of Airborne Virulent Rhodococcus equi at Horse Breeding Farms
Kuskie, Kyle Ryan
2012-02-14
Rhodococcus equi causes severe pneumonia, resulting in disease and sometimes death of foals. Infection is thought to occur by inhalation of dust contaminated with virulent R equi. A recent study of 3 horse breeding farms in Ireland found airborne...
Sun photometer and airborne in situ and ship-based lidar measurements B. Schmid,1 D. A. Hegg,2 J. Wang (closure) between solar beam attenuation by aerosols and water vapor measured by airborne Sun photometry agreement with airborne Sun photometry in the marine boundary layer but is considerably lower in layers
Gravity-driven intrusions in stratified fluids
Maurer, Benjamin Dudley
2011-01-01
5.5.1 Five interleaving interfacial gravity currents 5.5.2Ten interleaving interfacial gravity currents . 5.6partial- depth intrusive gravity currents,” Atmosphere -
ARM Airborne Continuous carbon dioxide measurements
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Biraud, Sebastien
2013-03-26
The heart of the AOS CO2 Airborne Rack Mounted Analyzer System is the AOS Manifold. The AOS Manifold is a nickel coated aluminum analyzer and gas processor designed around two identical nickel-plated gas cells, one for reference gas and one for sample gas. The sample and reference cells are uniquely designed to provide optimal flushing efficiency. These cells are situated between a black-body radiation source and a photo-diode detection system. The AOS manifold also houses flow meters, pressure sensors and control valves. The exhaust from the analyzer flows into a buffer volume which allows for precise pressure control of the analyzer. The final piece of the analyzer is the demodulator board which is used to convert the DC signal generated by the analyzer into an AC response. The resulting output from the demodulator board is an averaged count of CO2 over a specified hertz cycle reported in volts and a corresponding temperature reading. The system computer is responsible for the input of commands and therefore works to control the unit functions such as flow rate, pressure, and valve control.The remainder of the system consists of compressors, reference gases, air drier, electrical cables, and the necessary connecting plumbing to provide a dry sample air stream and reference air streams to the AOS manifold.
ARM Airborne Continuous carbon dioxide measurements
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Biraud, Sebastien
The heart of the AOS CO2 Airborne Rack Mounted Analyzer System is the AOS Manifold. The AOS Manifold is a nickel coated aluminum analyzer and gas processor designed around two identical nickel-plated gas cells, one for reference gas and one for sample gas. The sample and reference cells are uniquely designed to provide optimal flushing efficiency. These cells are situated between a black-body radiation source and a photo-diode detection system. The AOS manifold also houses flow meters, pressure sensors and control valves. The exhaust from the analyzer flows into a buffer volume which allows for precise pressure control of the analyzer. The final piece of the analyzer is the demodulator board which is used to convert the DC signal generated by the analyzer into an AC response. The resulting output from the demodulator board is an averaged count of CO2 over a specified hertz cycle reported in volts and a corresponding temperature reading. The system computer is responsible for the input of commands and therefore works to control the unit functions such as flow rate, pressure, and valve control.The remainder of the system consists of compressors, reference gases, air drier, electrical cables, and the necessary connecting plumbing to provide a dry sample air stream and reference air streams to the AOS manifold.
On the no-gravity limit of gravity
J. Kowalski-Glikman; M. Szczachor
2012-12-21
We argue that Relative Locality may arise in the no gravity $G\\rightarrow0$ limit of gravity. In this limit gravity becomes a topological field theory of the BF type that, after coupling to particles, may effectively deform its dynamics. We briefly discuss another no gravity limit with a self dual ground state as well as the topological ultra strong $G\\rightarrow\\infty$ one.
Polchinski, Joseph [Kavli Institute for Theoretical Physics
2010-09-01
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.
AIRBORNE, OPTICAL REMOTE SENSING OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION
Jerry Myers
2003-05-13
Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. This six-month technical report summarizes the progress for each of the proposed tasks, discusses project concerns, and outlines near-term goals. Ophir has completed a data survey of two major natural gas pipeline companies on the design requirements for an airborne, optical remote sensor. The results of this survey are disclosed in this report. A substantial amount of time was spent on modeling the expected optical signal at the receiver at different absorption wavelengths, and determining the impact of noise sources such as solar background, signal shot noise, and electronic noise on methane and ethane gas detection. Based upon the signal to noise modeling and industry input, Ophir finalized the design requirements for the airborne sensor, and released the critical sensor light source design requirements to qualified vendors. Responses from the vendors indicated that the light source was not commercially available, and will require a research and development effort to produce. Three vendors have responded positively with proposed design solutions. Ophir has decided to conduct short path optical laboratory experiments to verify the existence of methane and absorption at the specified wavelength, prior to proceeding with the light source selection. Techniques to eliminate common mode noise were also evaluated during the laboratory tests. Finally, Ophir has included a summary of the potential concerns for project success and has established future goals.
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
Loop quantum gravity and observations
A. Barrau; J. Grain
2015-10-28
Quantum gravity has long been thought to be completely decoupled from experiments or observations. Although it is true that smoking guns are still missing, there are now serious hopes that quantum gravity phenomena might be tested. We review here some possible ways to observe loop quantum gravity effects either in the framework of cosmology or in astroparticle physics.
Even-dimensional topological gravity from Chern-Simons gravity
Nelson Merino; Alfredo Perez; Patricio Salgado
2009-10-08
It is shown that the topological action for gravity in 2n-dimensions can be obtained from the 2n+1-dimensional Chern-Simons gravity genuinely invariant under the Poincare group. The 2n-dimensional topological gravity is described by the dynamics of the boundary of a 2n+1-dimensional Chern-Simons gravity theory with suitable boundary conditions. The field $\\phi^{a}$, which is necessary to construct this type of topological gravity in even dimensions, is identified with the coset field associated with the non-linear realizations of the Poincare group ISO(d-1,1).
From Classical To Quantum Gravity: Introduction to Loop Quantum Gravity
Kristina Giesel; Hanno Sahlmann
2013-01-02
We present an introduction to the canonical quantization of gravity performed in loop quantum gravity, based on lectures held at the 3rd quantum geometry and quantum gravity school in Zakopane in 2011. A special feature of this introduction is the inclusion of new proposals for coupling matter to gravity that can be used to deparametrize the theory, thus making its dynamics more tractable. The classical and quantum aspects of these new proposals are explained alongside the standard quantization of vacuum general relativity in loop quantum gravity.
Massive gravity as a limit of bimetric gravity
Martin-Moruno, Prado; Visser, Matt
2013-01-01
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.
Quantum Gravity and Turbulence
Vishnu Jejjala; Djordje Minic; Y. Jack Ng; Chia-Hsiung Tze
2010-05-18
We apply recent advances in quantum gravity to the problem of turbulence. Adopting the AdS/CFT approach we propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. In the gravitational context, turbulence is intimately related to the properties of spacetime, or quantum, foam.
Christian Wiesendanger
2009-07-25
Isometrodynamics (ID), the gauge theory of the group of volume-preserving diffeomorphisms of an "inner" D-dimensional flat space, is tentatively interpreted as a fundamental theory of gravity. Dimensional analysis shows that the Planck length l_P - and through it \\hbar and \\Gamma - enters the gauge field action linking ID and gravity in a natural way. Noting that the ID gauge field couples solely through derivatives acting on "inner" space variables all ID fields are Taylor-expanded in "inner" space. Integrating out the "inner" space variables yields an effective field theory for the coefficient fields with l_P^2 emerging as the expansion parameter. For \\hbar goint to zero only the leading order field does not vanish. This classical field couples to the matter Noether currents and charges related to the translation invariance in "inner" space. A model coupling this leading order field to a matter point source is established and solved. Interpreting the matter Noether charge in terms of gravitational mass Newton's inverse square law is finally derived for a static gauge field source and a slowly moving test particle. Gravity emerges as potentially related to field variations over "inner" space and might microscopically be described by the ID gauge field or equivalently by an infinite string of coefficient fields only the leading term of which is related to the macroscopical effects of gravity.
Goldstein, Allen
Airborne observations of methane emissions from rice cultivation in the Sacramento Valley 2012; accepted 7 October 2012; published 8 December 2012. [1] Airborne measurements of methane (CH4 is not accounted for in the CARB inventory. Citation: Peischl, J., et al. (2012), Airborne observations of methane
Steps towards Quality Improvement of Airborne Laser Scanner Data
Vosselman, George
, and forestry management. However, to guarantee this level of data quality the measurements must be as closeSteps towards Quality Improvement of Airborne Laser Scanner Data A Behan1 , H-G Maas2 and G for the acquisition of 2.5D data, mainly for use in topographic and mapping operations. In recent years, however
Automatic Construction of Building Footprints from Airborne LIDAR Data
Chen, Shu-Ching
1 Automatic Construction of Building Footprints from Airborne LIDAR Data Keqi Zhang, Jianhua Yan. INTRODUCTION BUILDING footprints are one of the fundamental GIS data components that can be used to estimate, and estimation of building base elevation for flood insurance [2]. In addition, footprint data in combination
Airborne lidar detection and characterization of internal waves in a
Shaw, Joseph A.
on the strength of the wind. This tends to create a layer of less dense water on top of the more dense water below of water with lower density at the surface. This layer is typically mixed with the water below. The airborne lidar detected a thin plankton layer at the bottom of the upper layer of the water
Quality Assurance Program Plan for radionuclide airborne emissions monitoring
Vance, L.M.
1993-07-01
This Quality Assurance Program Plan (QAPP) describes the quality assurance requirements and responsibilities for radioactive airborne emissions measurements activities from regulated stacks are controlled at the Hanford Site. Detailed monitoring requirements apply to stacks exceeding 1% of the standard of 10 mrem annual effective dose equivalent to the maximally exposed individual from operations of the Hanford Site.
EPLA: Energy-balancing Packets Scheduling for Airborne Relaying Networks
New South Wales, University of
of unmanned aerial vehicles (UAVs). We propose an energy-efficient relaying scheme which is able to overcomeEPLA: Energy-balancing Packets Scheduling for Airborne Relaying Networks Kai Li1 Wei Ni2 Xin Wang3 then schedules UAVs' forwarding with guaranteed success rates and balanced energy consumption. Such scheduling
Evaluation of Mali, West Africa Airborne Measurements to Access the
Delene, David J.
Evaluation of Mali, West Africa Airborne Measurements to Access the Potential of Enhancing if cloud seeding in Mali could be beneficial.c Â·Identify optimal seeding method for enhancing precipitation in the Mali region based on conceptual models. #12;Measurement Importance Â· The potential to enhancing
Three Years of Airborne Measurements in Mali, West Africa
Delene, David J.
Three Years of Airborne Measurements in Mali, West Africa David Delene Department of Atmospheric of adapting operational programs from other locations to the Mali region. Â· Advance local scientific knowledge Measurement Objectives Â· Determine the variability of aerosol and cloud properties in Mali and how
Evaluation of Mali, West Africa Airborne Measurements to Access the
Delene, David J.
Evaluation of Mali, West Africa Airborne Measurements to Access the Potential of Enhancing Determine if cloud seeding in Mali could be beneficial.b Help determine what is the optimal seeding method for enhancing precipitation in the Mali region. #12;Measurement Importance The potential to enhancing
R. Bluhm
2013-07-22
Gravitational theories with Lorentz violation must account for a number of possible features in order to be consistent theoretically and phenomenologically. A brief summary of these features is given here. They include evasion of a no-go theorem, connections between spontaneous Lorentz breaking and diffeomorphism breaking, the appearance of massless Nambu-Goldstone modes and massive Higgs modes, and the possibility of a Higgs mechanism in gravity.
Gravity, Dimension, Equilibrium, & Thermodynamics
Jerome Perez
2006-03-30
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.
Massive Gravity from Higher Derivative Gravity with Boundary Conditions
Minjoon Park; Lorenzo Sorbo
2012-10-29
With an appropriate choice of parameters, a higher derivative theory of gravity can describe a normal massive sector and a ghost massless sector. We show that, when defined on an asymptotically de Sitter spacetime with Dirichlet boundary conditions, such a higher derivative gravity can provide a framework for a unitary theory of massive gravity in four spacetime dimensions. The resulting theory is free not only of higher derivative ghosts but also of the Boulware-Deser mode.
Marcus S. Cohen
2002-08-02
Quantum gravity has been so elusive because we have tried to approach it by two paths which can never meet: quantum mechanics and general relativity. These contradict each other not only in superdense regimes, but also in the vacuum. We explore a straight road to quantum gravity here--the one mandated by Clifford-algebra covariance. This bridges the gap from microscales--where the massive Dirac propagator is a sum over null zig-zags--to macroscales--where we see the energy-momentum current, *T and the resulting Einstein curvature, *G. For massive particles, *T flows in the "cosmic time" direction, y^0--centrifugally in an expanding universe. Neighboring centrifugal currents of *T present opposite spacetime vorticities *G to the boundaries of each others' worldtubes, so they advect--i.e. attract, as we show here by integrating a Spin^c-4 Lagrangian by parts in the spinfluid regime. This boundary integral not only explains why stress-energy *T is the source for gravitational curvature *G, but also gives a value for the gravitational constant, kappa(x^0) that depends on the current scale factor of our expanding Friedmann 3-brane. On the microscopic scale, quantum gravity appears naturally as the statistical mechanics of null zig-zags of massive particles in "imaginary time," y^0.
Improved Steam Assisted Gravity Drainage (SAGD) Performance with Solvent as Steam Additive
Li, Weiqiang
2011-02-22
Steam Assisted Gravity Drainage (SAGD) is used widely as a thermal recovery technique in Canada to produce a very viscous bitumen formation. The main research objectives of this simulation and experimental study are to investigate oil recovery...
Kulisek, Jonathan A.; Schweppe, John E.; Stave, Sean C.; Bernacki, Bruce E.; Jordan, David V.; Stewart, Trevor N.; Seifert, Carolyn E.; Kernan, Warnick J.
2015-06-01
Helicopter-mounted gamma-ray detectors can provide law enforcement officials the means to quickly and accurately detect, identify, and locate radiological threats over a wide geographical area. The ability to accurately distinguish radiological threat-generated gamma-ray signatures from background gamma radiation in real time is essential in order to realize this potential. This problem is non-trivial, especially in urban environments for which the background may change very rapidly during flight. This exacerbates the challenge of estimating background due to the poor counting statistics inherent in real-time airborne gamma-ray spectroscopy measurements. To address this, we have developed a new technique for real-time estimation of background gamma radiation from aerial measurements. This method is built upon on the noise-adjusted singular value decomposition (NASVD) technique that was previously developed for estimating the potassium (K), uranium (U), and thorium (T) concentrations in soil post-flight. The method can be calibrated using K, U, and T spectra determined from radiation transport simulations along with basis functions, which may be determined empirically by applying maximum likelihood estimation (MLE) to previously measured airborne gamma-ray spectra. The method was applied to both measured and simulated airborne gamma-ray spectra, with and without man-made radiological source injections. Compared to schemes based on simple averaging, this technique was less sensitive to background contamination from the injected man-made sources and may be particularly useful when the gamma-ray background frequently changes during the course of the flight.
Geometric scalar theory of gravity
Novello, M.; Bittencourt, E.; Goulart, E.; Salim, J.M.; Toniato, J.D.; Moschella, U. E-mail: eduhsb@cbpf.br E-mail: egoulart@cbpf.br E-mail: toniato@cbpf.br
2013-06-01
We present a geometric scalar theory of gravity. Our proposal will be described using the ''background field method'' introduced by Gupta, Feynman, Deser and others as a field theory formulation of general relativity. We analyze previous criticisms against scalar gravity and show how the present proposal avoids these difficulties. This concerns not only the theoretical complaints but also those related to observations. In particular, we show that the widespread belief of the conjecture that the source of scalar gravity must be the trace of the energy-momentum tensor — which is one of the main difficulties to couple gravity with electromagnetic phenomenon in previous models — does not apply to our geometric scalar theory. From the very beginning this is not a special relativistic scalar gravity. The adjective ''geometric'' pinpoints its similarity with general relativity: this is a metric theory of gravity. Some consequences of this new scalar theory are explored.
Entropic Gravity in Rindler Space
Edi Halyo
2011-04-13
We show that Rindler horizons are entropic screens and gravity is an entropic force in Rindler space by deriving the Verlinde entropy formula from the focusing of light due to a mass close to the horizon. Consequently, gravity is also entropic in the near horizon regions of Schwarzschild and de Sitter space-times. In different limits, the entropic nature of gravity in Rindler space leads to the Bekenstein entropy bound and the uncertainty principle.
Shan Gao
2011-07-16
The remarkable connections between gravity and thermodynamics seem to imply that gravity is not fundamental but emergent, and in particular, as Verlinde suggested, gravity is probably an entropic force. In this paper, we will argue that the idea of gravity as an entropic force is debatable. It is shown that there is no convincing analogy between gravity and entropic force in Verlinde's example. Neither holographic screen nor test particle satisfies all requirements for the existence of entropic force in a thermodynamics system. Furthermore, we show that the entropy increase of the screen is not caused by its statistical tendency to increase entropy as required by the existence of entropic force, but in fact caused by gravity. Therefore, Verlinde's argument for the entropic origin of gravity is problematic. In addition, we argue that the existence of a minimum size of spacetime, together with the Heisenberg uncertainty principle in quantum theory, may imply the fundamental existence of gravity as a geometric property of spacetime. This may provide a further support for the conclusion that gravity is not an entropic force.
Peter West
2014-11-04
We consider the equation of motion in the gravity sector that arises from the non-linear realisation of the semi-direct product of E11 and its first fundamental representation, denoted by l1, in four dimensions. This equation is first order in derivatives and at low levels relates the usual field of gravity to a dual gravity field. When the generalised space-time is restricted to be the usual four dimensional space-time we show that this equation does correctly describe Einstein's theory at the linearised level. We also comment on previous discussions of dual gravity.
An Underlying Theory for Gravity
Yuan K. Ha
2012-08-14
A new direction to understand gravity has recently been explored by considering classical gravity to be a derived interaction from an underlying theory. This underlying theory would involve new degrees of freedom at a deeper level and it would be structurally different from classical gravitation. It may conceivably be a quantum theory or a non-quantum theory. The relation between this underlying theory and Einstein's gravity is similar to the connection between statistical mechanics and thermodynamics. We discuss the apparent lack of evidence of any quantum nature of gravity in this context.
Lifshitz Gravity for Lifshitz Holography
Tom Griffin; Petr Horava; Charles M. Melby-Thompson
2012-11-20
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.
The role of information in gravity
M. Spaans
2009-07-24
It is argued that particle-specific information on energy-momentum adjusts the strength of gravity. This form of gravity has no free parameters, preserves Einstein gravity locally and predicts 6 times stronger accelerations on galaxy scales.
Gravity-Driven Intrusions in Stratified Fluids
Maurer, Benjamin D.
2011-01-01
5.5.1 Five interleaving interfacial gravity currents 5.5.2Ten interleaving interfacial gravity currents . 5.6in Iceland showing multiple gravity-driven intrusions c ´
K. H. Mariwalla
2002-05-28
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.
Durmus A. Demir
2011-12-11
It is shown that, under a conformal transformation with reference to the Higgs field, the Higgs boson can be completely decoupled from electroweak interactions with no apparent change in known properties of leptons, quarks and vector bosons. Higgs boson becomes part of a scalar-tensor gravity which can be relevant for Dark Energy. It interacts with matter sector via higher-dimensional terms (e.g. neutrino Majorana mass), and via the fields (of new physics) whose masses are not generated by the Higgs mechanism. Dark Matter and two-Higgs-doublet model are the simplest examples.
Lubricated viscous gravity currents
Kowal, Katarzyna N.; Worster, M. Grae
2015-02-10
) at their base. The presence of subglacial meltwater can be attributed to geothermal heating, frictional heating from glacier sliding, and ice melting under pressure from the weight of the ice † Email address for correspondence: K.Kowal@damtp.cam.ac.uk 2 K. N... -fed and a constant head was maintained in the reservoir. To minimize the amount Lubricated viscous gravity currents 15 mirror syringe pump reservoir glass sheet perspex sheet screen Golden Syrup Salt Solution 1 m Figure 6: Schematic of our experimental...
Real-time airborne particle analyzer
Reilly, Peter T.A.
2012-10-16
An aerosol particle analyzer includes a laser ablation chamber, a gas-filled conduit, and a mass spectrometer. The laser ablation chamber can be operated at a low pressure, which can be from 0.1 mTorr to 30 mTorr. The ablated ions are transferred into a gas-filled conduit. The gas-filled conduit reduces the electrical charge and the speed of ablated ions as they collide and mix with buffer gases in the gas-filled conduit. Preferably, the gas filled-conduit includes an electromagnetic multipole structure that collimates the nascent ions into a beam, which is guided into the mass spectrometer. Because the gas-filled conduit allows storage of vast quantities of the ions from the ablated particles, the ions from a single ablated particle can be analyzed multiple times and by a variety of techniques to supply statistically meaningful analysis of composition and isotope ratios.
An inverse modelling technique for glass forming by gravity sagging
Stokes, Yvonne
Department of Civil and Environmental Engineering, Technion, Israel Institute of Technology, 32000 Haifa, Israel. b or as a mould surface for casting plastic ophthalmic lenses; the curvature of this surface must meet the design,5], in thermoforming of plastics [1,2,14,20] and in forging [7,13,21], to name a few which appear in the literature
Superbounce and Loop Quantum Cosmology Ekpyrosis from Modified Gravity
V. K. Oikonomou
2015-04-07
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 $CC(M)$.
Zhou, Lijun
2010-10-12
This study explored different chemical characterization methods of agricultural and urban airborne particulate matter. Three different field campaigns are discussed. For the agricultural aerosols, measurement of the chemical ...
Spin-gravity coupling and gravity-induced quantum phases
Giorgio Papini
2007-09-06
External gravitational fields induce phase factors in the wave functions of particles. The phases are exact to first order in the background gravitational field, are manifestly covariant and gauge invariant and provide a useful tool for the study of spin-gravity coupling and of the optics of particles in gravitational or inertial fields. We discuss the role that spin-gravity coupling plays in particular problems.
Gravity's Rainbow: a bridge towards Horava-Lifshitz gravity
Remo Garattini; Emmanuel N. Saridakis
2014-11-25
We investigate the connection between Gravity's Rainbow and Horava-Lifshitz gravity, since both theories incorporate a modification in the UltraViolet regime which improves their quantum behavior at the cost of the Lorentz invariance loss. In particular, extracting the Wheeler-De Witt equations of the two theories in the case of Friedmann-Lemaitre-Robertson-Walker and spherically symmetric geometries, we establish a correspondence that bridges them.
Cosmological perturbations in unimodular gravity
Gao, Caixia; Brandenberger, Robert H.; Cai, Yifu; Chen, Pisin E-mail: rhb@hep.physics.mcgill.ca E-mail: chen@slac.stanford.edu
2014-09-01
We study cosmological perturbation theory within the framework of unimodular gravity. We show that the Lagrangian constraint on the determinant of the metric required by unimodular gravity leads to an extra constraint on the gauge freedom of the metric perturbations. Although the main equation of motion for the gravitational potential remains the same, the shift variable, which is gauge artifact in General Relativity, cannot be set to zero in unimodular gravity. This non-vanishing shift variable affects the propagation of photons throughout the cosmological evolution and therefore modifies the Sachs-Wolfe relation between the relativistic gravitational potential and the microwave temperature anisotropies. However, for adiabatic fluctuations the difference between the result in General Relativity and unimodular gravity is suppressed on large angular scales. Thus, no strong constraints on the theory can be derived.
Gravity Currents in Aquatic Canopies
Tanino, Yukie
A lock exchange experiment is used to investigate the propagation of gravity currents through a random array of rigid, emergent cylinders which represents a canopy of aquatic plants. As canopy drag increases, the propagating ...
Gravity as an Entropic Phenomenon
Abhiram Chivukula
2010-11-19
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
2010-01-01
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
2014-09-12
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.
Smith, Christina Lynn
2005-08-29
The mixing layer (ML) heights inferred from radiosondes, wind profilers, airborne lidar, airborne microwave temperature profiler (MTP), and in-situ aircraft data were compared during the Texas 2000 Air Quality Study in the Houston area...
EVALUATION OF AIRBORNE AND SATELLITE ELECTRO-OPTICAL SENSORS PERFORMANCES BY USE OF HIGH, F-91761 Palaiseau, France, email : karine.caillault@onera.fr KEYWORDS: sensor performance require optronic sensors, onboard satellite or airborne platform. Performances limitation of these sensors
Dualities and Emergent Gravity: Gauge/Gravity Duality
Sebastian de Haro
2015-09-09
In this paper I develop a framework for relating dualities and emergence: two notions that are close to each other but also exclude one another. I adopt the conception of duality as 'isomorphism', cashing it out in terms of three conditions. These three conditions prompt two conceptually different ways in which a duality can be modified to make room for emergence; and I argue that this exhausts the possibilities for combining dualities and emergence (via coarse-graining). I apply this framework to gauge/gravity dualities, considering in detail three examples: AdS/CFT, Verlinde's scheme, and black holes. My main point about gauge/gravity dualities is that the theories involved, qua theories of gravity, must be background-independent. I distinguish two senses of background-independence: (i) minimalistic and (ii) extended. The former is sufficiently strong to allow for a consistent theory of quantum gravity; and AdS/CFT is background-independent on this account; while Verlinde's scheme best fits the extended sense. I argue that this extended sense should be applied with some caution: on pain of throwing the baby (general relativity) out with the bath-water (extended background-independence). Nevertheless, it is an interesting and potentially fruitful heuristic principle for quantum gravity theory construction. The interpretation of dualities is articulated in terms of: (i) epistemic and metaphysical commitments; (ii) parts vs. wholes. I then analyse the emergence of gravity in gauge/gravity dualities in terms of the two available conceptualisations of emergence; and I show how emergence in AdS/CFT and in Verlinde's scenario differ from each other. Finally, I give a novel derivation of the Bekenstein-Hawking black hole entropy formula based on Verlinde's scheme; the derivation sheds light on several aspects of Verlinde's scheme and how it compares to Bekenstein's original calculation.
Prospecting by sampling and analysis of airborne particulates and gases
Sehmel, G.A.
1984-05-01
A method is claimed for prospecting by sampling airborne particulates or gases at a ground position and recording wind direction values at the time of sampling. The samples are subsequently analyzed to determine the concentrations of a desired material or the ratios of the desired material to other identifiable materials in the collected samples. By comparing the measured concentrations or ratios to expected background data in the vicinity sampled, one can select recorded wind directions indicative of the upwind position of the land-based source of the desired material.
ARM - Evaluation Product - Airborne Visible/Infrared Imaging Spectrometer
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Comments? WeDatastreamstps DocumentationAtlanticENA Contacts ENA Related Links(AVIRIS) ProductsAirborne
E. Gaztanaga; R. Juszkiewicz
2001-08-21
We present a new constraint on the biased galaxy formation picture. Gravitational instability theory predicts that the two-point mass density correlation function, \\xi(r), has an inflection point at the separation r=r_0, corresponding to the boundary between the linear and nonlinear regime of clustering, \\xi = 1. We show how this feature can be used to constrain the square of the biasing parameter, b^2 = \\xi_g / \\xi on scales r = r_0, where \\xi_g is the galaxy-galaxy correlation function, allowed to differ from \\xi. We apply our method to real data: the \\xi_g(r), estimated from the APM galaxy survey. Our results suggest that the APM galaxies trace the mass at separations r > 5 Mpc/h, where h is the Hubble constant in units of 100 km/s Mpc. The present results agree with earlier studies, based on comparing higher order correlations in the APM with weakly non-linear perturbation theory. Both approaches constrain the "b" factor to be within 20% of unity. If the existence of the feature we identified in the APM \\xi_g(r) -- the inflection point near \\xi_g = 1 -- is confirmed by more accurate surveys, we may have discovered gravity's smoking gun: the long awaited ``shoulder'' in \\xi, predicted by Gott and Rees 25 years ago.
D. Fargion
2005-11-23
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.
Evaluation of Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and Moderate Resolution the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and the Moderate Resolution Imaging Spectrometer (MODIS). Key goals were to assess the nature of these relationships as they varied between sensors
Khuri-Yakub, Butrus T. "Pierre"
Non-contact thermoacoustic detection of embedded targets using airborne-capacitive micromachined to IP: 171.64.84.210 On: Thu, 26 Feb 2015 05:19:31 #12;Non-contact thermoacoustic detection of embedded provides permittivity contrast, and ultra- sensitive airborne-ultrasound detection measures thermoacoustic
Mason, Andrew
Abstract--Airborne pollution and explosive gases threaten human health and occupational safety and a thumb-drive sized prototype system. I. INTRODUCTION xposure to air pollution consistently ranks among to occupational safety as energy demands rise. Airborne pollutants and explosive gases vary in both time and space
Airborne Volcanic Ash--A Global Threat to Aviation U.S. Department of the Interior
Airborne Volcanic Ash--A Global Threat to Aviation U.S. Department of the Interior U.S. Geological on the aviation industry. Airborne volcanic ash can be a serious hazard to aviation even hundreds of miles from an eruption. Encounters with high-concentration ash clouds can diminish visibility, damage flight control
Airborne MAX-DOAS measurements over California: Testing the NASA OMI tropospheric NO2 product
Airborne MAX-DOAS measurements over California: Testing the NASA OMI tropospheric NO2 product Hilke] Airborne Multi-AXis Differential Optical Absorption Spectroscopy (AMAX-DOAS) measurements of NO2 are compared to the NASA Ozone Monitoring Instrument (OMI) tropospheric vertical columns (data product v2
Near-coastal surface water velocity field estimation using airborne remote sensing11
Near-coastal surface water velocity field estimation using airborne remote sensing11 Tim J Malthus1. With airborne remote sensing, however, it is possible to determine synoptic changes in velocity fields because properties of successive remotely sensed images may be used to estimate velocity vectors associated
2007-01-01
Biomass and Bioenergy 31 (2007) 646655 Estimating biomass of individual pine trees using airborne biomass and bio-energy feedstocks. The overall goal of this study was to develop a method for assessing aboveground biomass and component biomass for individual trees using airborne lidar data in forest settings
Analyses of in-situ airborne volcanic ash from the February 2000 eruption of Hekla Volcano, Iceland
Ma, Chi
Analyses of in-situ airborne volcanic ash from the February 2000 eruption of Hekla Volcano, Iceland-8 NASA research aircraft inadvertently flew into an airborne volcanic ash plume from the 26 February spectrophotometer analyses. These analyses confirm that the DC-8 encountered airborne volcanic ash from Hekla
Conformal Lifshitz Gravity from Holography
Tom Griffin; Petr Horava; Charles M. Melby-Thompson
2012-04-03
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.
Howard, Jeff W.
2005-05-10
with others such as a small group discussion or the question-answer technique to al- low the 4-H?ers to express their opinion. 2. Illustrated talk This method is an offshoot of the lecture technique, in which the teacher supports the talk with such things... as drawings, posters, copies of articles and other materials. The drawings or posters need not be professional art pieces, they need only be interesting and clear. For ex- ample, in entomology, rather than just talking about the various shapes...
New Models of f(R) Theories of Gravity
J. Kluson
2009-11-04
We introduce new models of f(R) theories of gravity that are generalization of Horava-Lifshitz gravity.
The Gravity Field of the Earth and Coriolis Effects.... The gravity field
Riser, Stephen C.
The Gravity Field of the Earth and Coriolis Effects.... The gravity field Stationary particles #12;Gravity.... Newton's Universal Law of Gravitation: The force between any two particles having.673 ×10-11 newton-meter2/kilogram2) #12;Gravity.... In vector form, or, 21 č force on 2 due to 1 12 č
Modified Entropic Gravity and Cosmology
Miguel Zumalacarregui
2012-02-06
It has been recently proposed that gravity might be an entropic force. Although a well defined fundamental description for such a mechanism is still lacking, it is still possible to address the viability of phenomenological models of entropic-inspired modified gravities. I will summarize some recent work directed to using cosmology as a tool to constraint scenarios in which the modifications are aimed to explain the physics behind dark energy and inflation. A phenomenological modification is able to explain cosmic acceleration at the background level and fit observations, but simple inflation models with higher curvature corrections are in conflict with late time matter domination.
Starobinsky Model in Rainbow Gravity
Chatrabhuti, Auttakit; Channuie, Phongpichit
2015-01-01
In this work, we study Starobinsky model of inflation in the context of gravity's rainbow theory. We propose that gravity rainbow functions can be written in the power-law form of the Hubble parameter. We present a detailed derivation of the spectral index of curvature perturbation and the tensor-to-scalar ratio and compare the predictions of our models with Planck 2015 data. We discover, by taking $N_{k}=70$ e-folds and requiring our predictions to agree with the Planck data at the one sigma confidence level, the rainbow parameter would satisfy $\\lambda\\lesssim 1.0$.
de Sitter gravity/Euclidean conformal gravity correspondence
Chatterjee, Atreya
2015-01-01
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.
Gravity Transform for Input Conditioning in
Paiva, António R. C.
Gravity Transform for Input Conditioning in Brain Machine Interfaces António R. C. Paiva, José C. Motivation 2. Methods i. Gravity Transform ii. Modeling and output sensitivity analysis 3. Data Analysis #12;3 Outline 1. Motivation 2. Methods i. Gravity Transform ii. Modeling and output sensitivity analysis 3. Data
Emergent 4D Gravity from Matrix Models
Harold Steinacker
2007-12-19
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.
Initial assessment of an airborne Ku-band polarimetric SAR.
Raynal, Ann Marie; Doerry, Armin Walter
2013-02-01
Polarimetric synthetic aperture radar (SAR) has been used for a variety of dual-use research applications since the 1940's. By measuring the direction of the electric field vector from radar echoes, polarimetry may enhance an analyst's understanding of scattering effects for both earth monitoring and tactical surveillance missions. Polarimetry may provide insight into surface types, materials, or orientations for natural and man-made targets. Polarimetric measurements may also be used to enhance the contrast between scattering surfaces such as man-made objects and their surroundings. This report represents an initial assessment of the utility of, and applications for, polarimetric SAR at Ku-band for airborne or unmanned aerial systems.
Method for measuring the size distribution of airborne rhinovirus
Russell, M.L.; Goth-Goldstein, R.; Apte, M.G.; Fisk, W.J.
2002-01-01
About 50% of viral-induced respiratory illnesses are caused by the human rhinovirus (HRV). Measurements of the concentrations and sizes of bioaerosols are critical for research on building characteristics, aerosol transport, and mitigation measures. We developed a quantitative reverse transcription-coupled polymerase chain reaction (RT-PCR) assay for HRV and verified that this assay detects HRV in nasal lavage samples. A quantitation standard was used to determine a detection limit of 5 fg of HRV RNA with a linear range over 1000-fold. To measure the size distribution of HRV aerosols, volunteers with a head cold spent two hours in a ventilated research chamber. Airborne particles from the chamber were collected using an Andersen Six-Stage Cascade Impactor. Each stage of the impactor was analyzed by quantitative RT-PCR for HRV. For the first two volunteers with confirmed HRV infection, but with mild symptoms, we were unable to detect HRV on any stage of the impactor.
Chen, Gang; Lin, Yuehe
2008-07-20
Sensitive and selective detection techniques are of crucial importance for capillary electrophoresis (CE), microfluidic chips, and other microfluidic systems. Electrochemical detectors have attracted considerable interest for microfluidic systems with features that include high sensitivity, inherent miniaturization of both the detection and control instrumentation, low cost and power demands, and high compatibility with microfabrication technology. The commonly used electrochemical detectors can be classified into three general modes: conductimetry, potentiometry, and amperometry.
Willis, W.L.
1980-10-01
The discussion will be restricted to measurements of voltage and current. Also, although the measurements themselves should be as quantitative as possible, the discussion is rather nonquantitative. Emphasis is on types of instruments, how they may be used, and the inherent advantages and limitations of a given technique. A great deal of information can be obtained from good, clean voltage and current data. Power and impedance are obviously inherent if the proper time relationships are preserved. Often an associated, difficult-to-determine, physical event can be evaluated from the V-I data, such as a time-varying load characteristic, or the time of light emission, etc. The lack of active high voltage devices, such as 50-kV operational amplifiers, restricts measurement devices to passive elements, primarily R and C. There are a few more exotic techniques that are still passive in nature. There are several well-developed techniques for voltage measurements. These include: spark gaps; electrostatic meters; capacitive dividers; mixed RC dividers; and the electro-optic effect. Current is measured by either direct measurement of charge flow or by measuring the resulting magnetic field.
Testing universal relations of neutron stars with a nonlinear matter-gravity coupling theory
Sham, Y.-H.; Lin, L.-M.; Leung, P. T. E-mail: lmlin@phy.cuhk.edu.hk
2014-02-01
Due to our ignorance of the equation of state (EOS) beyond nuclear density, there is still no unique theoretical model for neutron stars (NSs). It is therefore surprising that universal EOS-independent relations connecting different physical quantities of NSs can exist. Lau et al. found that the frequency of the f-mode oscillation, the mass, and the moment of inertia are connected by universal relations. More recently, Yagi and Yunes discovered the I-Love-Q universal relations among the mass, the moment of inertia, the Love number, and the quadrupole moment. In this paper, we study these universal relations in the Eddington-inspired Born-Infeld (EiBI) gravity. This theory differs from general relativity (GR) significantly only at high densities due to the nonlinear coupling between matter and gravity. It thus provides us an ideal case to test how robust the universal relations of NSs are with respect to the change of the gravity theory. Due to the apparent EOS formulation of EiBI gravity developed recently by Delsate and Steinhoff, we are able to study the universal relations in EiBI gravity using the same techniques as those in GR. We find that the universal relations in EiBI gravity are essentially the same as those in GR. Our work shows that, within the currently viable coupling constant, there exists at least one modified gravity theory that is indistinguishable from GR in view of the unexpected universal relations.
Kenneth Dalton
2010-06-11
It is shown that gravity generates mass for the fermion. It does so by coupling directly with the spinor field. The coupling term is invariant with respect to the electroweak gauge group $ U(1) \\otimes SU(2)_L. $ It replaces the fermion mass term $ m\\bar{\\psi} \\psi $.
Overlap Fermion in External Gravity
Hiroto So; Masashi Hayakawa; Hiroshi Suzuki
2006-12-12
On a lattice, we construct an overlap Dirac operator which describes the propagation of a Dirac fermion in external gravity. The local Lorentz symmetry is manifestly realized as a lattice gauge symmetry, while the general coordinate invariance is expected to be restored only in the continuum limit. The lattice index density in the presence of a gravitational field is calculated.
Cosmological Hints of Modified Gravity ?
Eleonora Di Valentino; Alessandro Melchiorri; Joseph Silk
2015-09-24
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 ...
Astrophysical tests of modified gravity
Sakstein, Jeremy Aaron
2014-10-07
galaxies from our own. This means that the inferred distance to an unscreened galaxy using a stellar effect that depends on the law gravity will not agree with a measurement using a different method that is insensitive gravitational physics. We exploit...
Multisensor Fusion of Ground-based and Airborne Remote Sensing Data for Crop Condition Assessment
Zhang, Huihui
2012-02-14
provide applicators with guidance equipment configurations that can result in herbicide savings and optimized applications in other crops. The main focus of this research was to apply sensor fusion technology to ground-based and airborne imagery data...
Rohrbach, Amanda K. (Amanda Kaye)
2013-01-01
Due to a need for congestion relief, as well as a projected increase in capacity constraints, the US Military's Airborne Tactical Network (ATN) is at the onset of a technical transition of their communication hardware and ...
AIRBORNE, OPTICAL REMOTE SENSNG OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION
Jerry Myers
2005-04-15
Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. The scope of the work involved designing and developing an airborne, optical remote sensor capable of sensing methane and, if possible, ethane for the detection of natural gas pipeline leaks. Flight testing using a custom dual wavelength, high power fiber amplifier was initiated in February 2005. Ophir successfully demonstrated the airborne system, showing that it was capable of discerning small amounts of methane from a simulated pipeline leak. Leak rates as low as 150 standard cubic feet per hour (scf/h) were detected by the airborne sensor.
BNL-67857-AB AIRBORNE FORMALDEHYDE MEASUREMENT ON A NOAA WP-3 DURING THE 1999
BNL-67857-AB AIRBORNE FORMALDEHYDE MEASUREMENT ON A NOAA WP-3 DURING THE 1999 SOS SUMMER FIELD, San Francisco, CA, Dec. 15-19, 2000. Atmospheric formaldehyde (HCHO) concentration was determined
The metal content of airborne particles in Edinburgh: application to epidemiological research
Hibbs, L R; Beverland, Iain J; Heal, Mathew R; Agius, Raymond M; Elton, Robert A; Fowler, D; Cape, Neil
2002-01-01
Metals are putative causative agents in the association between ill health and exposure to airborne particles. We present preliminary results from an epidemiological study using exposure metrics of metal contained in ...
Not Available
1994-12-01
This document contains compiled data from the DOE Handbook on Airborne Release Fractions/Rates and Respirable Fractions for Nonreactor Nuclear facilities. Source data and example facilities utilized, such as the Plutonium Recovery Facility, are included.
The Dark Gravity model predictions for Gravity Probe B
Frederic Henry-Couannier
2007-10-23
The previous version of this article gave erroneous predictions. The correct uptodate predictions can be found in the section devoted to gravitomagnetism in the living review of the Dark Gravity theory: gr-qc/0610079 The most natural prediction is zero frame dragging and the same geodetic effect as predicted by GR. However, a straightforward extension of the theory could lead to the same frame-dragging as in GR.
New Branches of Massive Gravity
Comelli, Denis; Koyama, Kazuya; Pilo, Luigi; Tasinato, Gianmassimo
2015-01-01
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.
Nanodiamond interferometry meets quantum gravity
Albrecht, Andreas; Plenio, Martin B
2014-01-01
Interferometry with massive particles may have the potential to explore the limitations of standard quantum mechanics in particular where it concerns its boundary with general relativity and the yet to be developed theory of quantum gravity. This development is hindered considerably by the lack of experimental evidence and testable predictions. Analyzing effects that appear to be common to many of such theories, such as a modification of the energy dispersion and of the canonical commutation relation within the standard framework of quantum mechanics, has been proposed as a possible way forward. Here we analyze in some detail the impact of a modified energy-momentum dispersion in a Ramsey-Bord\\'e setup and provide achievable bounds of these correcting terms when operating such an interferometer with nanodiamonds. Thus, taking thermal and gravitational disturbances into account will show that without specific prerequisites, quantum gravity modifications may in general be suppressed requiring a revision of prev...
Hybrid metric-Palatini gravity
Capozziello, Salvatore; Koivisto, Tomi S; Lobo, Francisco S N; Olmo, Gonzalo J
2015-01-01
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.
Xavier Calmet; Priscila de Aquino
2009-10-08
It has recently been shown that if there is a large hidden sector in Nature, the scale of quantum gravity could be much lower than traditionally expected. We study the production of massless gravitons at the LHC and compare our results to those obtained in extra dimensional models. The signature in both cases is missing energy plus jets. In case of non observation, the LHC could be used to put the tightest limit to date on the value of the Planck mass.
Quantum gravity without Lorentz invariance
Sotiriou, Thomas P; Weinfurtner, Silke
2009-01-01
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
Solid Holography and Massive Gravity
Alberte, Lasma; Khmelnitsky, Andrei; Pujolas, Oriol
2015-01-01
Momentum dissipation is an important ingredient in condensed matter physics that requires a translation breaking sector. In the bottom-up gauge/gravity duality, this implies that the gravity dual is massive. We start here a systematic analysis of holographic massive gravity (HMG) theories, which admit field theory dual interpretations and which, therefore, might store interesting condensed matter applications. We show that there are many phases of HMG that are fully consistent effective field theories and which have been left overlooked in the literature. The most important distinction between the different HMG phases is that they can be clearly separated into solids and fluids. This can be done both at the level of the unbroken spacetime symmetries as well as concerning the elastic properties of the dual materials. We extract the modulus of rigidity of the solid HMG black brane solutions and show how it relates to the graviton mass term. We also consider the implications of the different HMGs on the electric...
Emergent Horava gravity in graphene
Volovik, G.E.; L. D. Landau Institute for Theoretical Physics, Kosygina 2, 119334 Moscow ; Zubkov, M.A.
2014-01-15
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, and the emergent low energy effective field theory has the anisotropic scaling. -- Highlights: •The tight-binding model for graphene with varying hopping parameters is considered. •The emergent gravity and emergent gauge fields are derived. •For the case of the multilayer graphene we obtain the analogue of Horava gravity with anisotropic scaling.
Dynamical 3-Space: Emergent Gravity
Reginald T Cahill
2011-02-16
The laws of gravitation devised by Newton, and by Hilbert and Einstein, have failed many experimental and observational tests, namely the bore hole g anomaly, flat rotation curves for spiral galaxies, supermassive black hole mass spectrum, uniformly expanding universe, cosmic filaments, laboratory G measurements, galactic EM bending, precocious galaxy formation,.. The response has been the introduction of the new epicycles: ``dark matter", ``dark energy", and others. To understand gravity we must restart with the experimental discoveries by Galileo, and following a heuristic argument we are led to a uniquely determined theory of a dynamical 3-space. That 3-space exists has been missed from the beginning of physics, although it was 1st directly detected by Michelson and Morley in 1887. Uniquely generalising the quantum theory to include this dynamical 3-space we deduce the response of quantum matter and show that it results in a new account of gravity, and explains the above anomalies and others. The dynamical theory for this 3-space involves G, which determines the dissipation rate of space by matter, and alpha, which experiments and observation reveal to be the fine structure constant. For the 1st time we have a comprehensive account of space and matter and their interaction - gravity.
Cosmological Hints of Modified Gravity ?
Di Valentino, Eleonora; Silk, Joseph
2015-01-01
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...
Airborne spread of foot-and-mouth disease - model intercomparison
Gloster, J; Jones, A; Redington, A; Burgin, L; Sorensen, J H; Turner, R; Dillon, M; Hullinger, P; Simpson, M; Astrup, P; Garner, G; Stewart, P; D'Amours, R; Sellers, R; Paton, D
2008-09-04
Foot-and-mouth disease is a highly infectious vesicular disease of cloven-hoofed animals caused by foot-and-mouth disease virus. It spreads by direct contact between animals, by animal products (milk, meat and semen), by mechanical transfer on people or fomites and by the airborne route - with the relative importance of each mechanism depending on the particular outbreak characteristics. Over the years a number of workers have developed or adapted atmospheric dispersion models to assess the risk of foot-and-mouth disease virus spread through the air. Six of these models were compared at a workshop hosted by the Institute for Animal Health/Met Office during 2008. A number of key issues emerged from the workshop and subsequent modelling work: (1) in general all of the models predicted similar directions for 'at risk' livestock with much of the remaining differences strongly related to differences in the meteorological data used; (2) determination of an accurate sequence of events is highly important, especially if the meteorological conditions vary substantially during the virus emission period; and (3) differences in assumptions made about virus release, environmental fate, and subsequent infection can substantially modify the size and location of the downwind risk area. Close relationships have now been established between participants, which in the event of an outbreak of disease could be readily activated to supply advice or modelling support.
Airborne radioactive effluent study at the Savannah River Plant
Blanchard, R.L.; Broadway, J.A.; Sensintaffar, E.L.; Kirk, W.P.; Kahn, B.; Garrett, A.J.
1984-07-01
Under the Clean Air Act, Sections 112 and 122 as amended in 1977, the Office of Radiation Programs (OPR) of the United States Environmental Protection Agency is currently developing standards for radionuclides emitted to the air by several source categories. In order to confirm source-term measurements and pathway calculations for radiation exposures to humans offsite, the ORP performs field studies at selected facilities that emit radionuclides. This report describes the field study conducted at the Savannah River Plant (SRP), a laboratory operated by E.I. du Pont de Nemours and Company for the US Department of Energy. This purpose of the study at ARP was to verify reported airborne releases and resulting radiation doses from the facility. Measurements of radionuclide releases for brief periods were compared with measurements performed by SRP staff on split samples and with annual average releases reported by SRP for the same facilities. The dispersion model used by SRP staff to calculate radiation doses offsite was tested by brief environmental radioactivity measurements performed simultaneously with the release measurements, and by examining radioactivity levels in environmental samples. This report describes in detail all measurements made and data collected during the field study and presents the results obtained. 34 references, 18 figures, 49 tables.
Entropic Motion in Loop Quantum Gravity
J. Manuel Garcia-Islas
2015-02-19
Entropic forces result from an increase of the entropy of a thermodynamical physical system. It has been proposed that gravity is such a phenomenon and many articles have appeared on the literature concerning this problem. Loop quantum gravity has also considered such possibility. We propose a new method in loop quantum gravity which reproduces an entropic force. By considering the interaction between a fixed gravity state space and a particle state in loop quantum gravity, we show that it leads to a mathematical description of a random walk of such particle. The random walk in special situations, can be seen as an entropic motion in such a way that the particle will move towards a location where entropy increases. This may prove that such theory can reproduce gravity as it is expected.
Short, Daniel
Chemical and isotopic properties and origin of coarse airborne particles collected by passive vehicle and industrial emissions, coal combustion (e.g. cooking, heating, power plants) represents
Simultaneous measurement of gravity acceleration and gravity gradient with an atom interferometer
Sorrentino, F.; Lien, Y.-H.; Rosi, G.; Tino, G. M.; Bertoldi, A.; Bodart, Q.; Cacciapuoti, L.; Angelis, M. de; Prevedelli, M.
2012-09-10
We demonstrate a method to measure the gravitational acceleration with a dual cloud atom interferometer; the use of simultaneous atom interferometers reduces the effect of seismic noise on the gravity measurement. At the same time, the apparatus is capable of accurate measurements of the vertical gravity gradient. The ability to determine the gravity acceleration and gravity gradient simultaneously and with the same instrument opens interesting perspectives in geophysical applications.
Gravity Data for west-central Colorado
Zehner, Richard
2012-04-06
Modeled Bouger Gravity data was extracted from the Pan American Center for Earth and Environmental Studies Gravity Database of the U.S. at http://irpsrvgis08.utep.edu/viewers/Flex/GravityMagnetic/GravityMagnetic_CyberShare/ on 2/29/2012. The downloaded text file was opened in an Excel spreadsheet. This spreadsheet data was then converted into an ESRI point shapefile in UTM Zone 13 NAD27 projection, showing location and gravity (in milligals). This data was then converted to grid and then contoured using ESRI Spatial Analyst. This dataset contains the original spreadsheet data, a point shapefile showing gravity station locations and Bouger gravity, and a line shapefile showing 1 milligal contours. Projection: UTM Zone 13 NAD27 Gravity Contour Shapefile Extent: West -108.366690 East -105.478730 North 40.932318 South 36.961606 Gravity Point Shapefile Extent: 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
Gravity from the extension of spatial diffeomorphisms
Szilard Farkas; Emil J. Martinec
2010-02-24
The possibility of the extension of spatial diffeomorphisms to a larger family of symmetries in a class of classical field theories is studied. The generator of the additional local symmetry contains a quadratic kinetic term and a potential term which can be a general (not necessarily local) functional of the metric. From the perspective of the foundation of Einstein's gravity our results are positive: The extended constraint algebra is either that of Einstein's gravity, or ultralocal gravity. If our goal is a simple modification of Einstein's gravity that for example makes it perturbatively renormalizable, as has recently been suggested, then our results show that there is no such theory within this class.
Growth histories in bimetric massive gravity
Berg, Marcus; Buchberger, Igor; Enander, Jonas; Mörtsell, Edvard; Sjörs, Stefan E-mail: igor.buchberger@kau.se E-mail: edvard@fysik.su.se
2012-12-01
We perform cosmological perturbation theory in Hassan-Rosen bimetric gravity for general homogeneous and isotropic backgrounds. In the de Sitter approximation, we obtain decoupled sets of massless and massive scalar gravitational fluctuations. Matter perturbations then evolve like in Einstein gravity. We perturb the future de Sitter regime by the ratio of matter to dark energy, producing quasi-de Sitter space. In this more general setting the massive and massless fluctuations mix. We argue that in the quasi-de Sitter regime, the growth of structure in bimetric gravity differs from that of Einstein gravity.
Momentum relaxation from the fluid/gravity correspondence
Mike Blake
2015-09-10
We provide a hydrodynamical description of a holographic theory with broken translation invariance. We use the fluid/gravity correspondence to systematically obtain both the constitutive relations for the currents and the Ward identity for momentum relaxation in a derivative expansion. Beyond leading order in the strength of momentum relaxation, our results differ from a model previously proposed by Hartnoll et al. As an application of these techniques we consider charge and heat transport in the boundary theory. We derive the low frequency thermoelectric transport coefficients of the holographic theory from the linearised hydrodynamics.
Momentum relaxation from the fluid/gravity correspondence
Blake, Mike
2015-01-01
We provide a hydrodynamical description of a holographic theory with broken translation invariance. We use the fluid/gravity correspondence to systematically obtain both the constitutive relations for the currents and the Ward identity for momentum relaxation in a derivative expansion. Beyond leading order in the strength of momentum relaxation, our results differ from a model previously proposed by Hartnoll et al. As an application of these techniques we consider charge and heat transport in the boundary theory. We derive the low frequency thermoelectric transport coefficients of the holographic theory from the linearised hydrodynamics.
On the stability of gravity with Dirichlet walls
Andrade, T; Kelly, WR; Marolf, D; Santos, JE
2015-01-01
Dirichlet problem : Fluid/Gravity on cut-off surfaces, JHEPWilsonian Approach to Fluid/Gravity Duality, JHEP 1103 (and other theories of gravity, Phys.Rev. D61 (2000) 084027 [
Gravity monitoring of CO2 movement during sequestration: Model studies
Gasperikova, E.
2008-01-01
right. Figure 14: Surface gravity response (?Gal) for theAbsolute and relative gravity integration for high precision2003, Seafloor Micro-gravity Survey of the Sleipner CO 2
Airborne flux measurements of Biogenic Isoprene over California
Misztal, P.; Karl, Thomas G.; Weber, Robin; Jonsson, H. H.; Guenther, Alex B.; Goldstein, Allen H.
2014-10-10
Biogenic Volatile Organic Compound (BVOC) fluxes were measured onboard the CIRPAS Twin Otter aircraft as part of the California Airborne BVOC Emission Research in Natural Ecosystem Transects (CABERNET) campaign during June 2011. The airborne virtual disjunct eddy covariance (AvDEC) approach used measurements from a PTR-MS and a wind radome probe to directly determine fluxes of isoprene, MVK+MAC, methanol, monoterpenes, and MBO over ~10,000-km of flight paths focusing on areas of California predicted to have the largest emissions of isoprene. The Fast Fourier Transform (FFT) approach was used to calculate fluxes over long transects of more than 15 km, most commonly between 50 and 150 km. The Continuous Wavelet Transformation (CWT) approach was used over the same transects to also calculate "instantaneous" fluxes with localization of both frequency and time independent of non-stationarities. Vertical flux divergence of isoprene is expected due to its relatively short lifetime and was measured directly using "racetrack" profiles at multiple altitudes. It was found to be linear and in the range 5% to 30% depending on the ratio of aircraft altitude to PBL height (z/zi). Fluxes were generally measured by flying consistently 1 at 400 m ±50 m (a.g.l.) altitude, and extrapolated to the surface according to the determined flux divergence. The wavelet-derived surface fluxes of isoprene averaged to 2 km spatial resolution showed good correspondence to Basal Emission Factor (BEF) landcover datasets used to drive biogenic VOC (BVOC) emission models. The surface flux of isoprene was close to zero over Central Valley crops and desert shrublands, but was very high (up to 15 mg m-2 h-1) above oak woodlands, with clear dependence of emissions on temperature and oak density. Isoprene concentrations of up to 8 ppb were observed at aircraft height on the hottest days and over the dominant source regions. While isoprene emissions from agricultural crop regions, shrublands, and coniferous forests were extremely low, high concentrations of methanol and monoterpenes were found above some of these regions. These observations demonstrate the ability to measure fluxes from specific sources by eddy covariance from an aircraft, and suggest the utility of measurements using fast response chemical sensors to constrain emission inventories and map out source distributions for a much broader array of trace gases than was observed in this study. This paper reports the first regional direct eddy covariance fluxes of isoprene. The emissions of VOCs measured from aircraft with 2 km spatial resolution can quantify the distribution of major sources providing the observations required for testing statewide emission inventories of these important trace gases. These measurements will be used in a future study to assess BVOC emission models and their driving variable datasets.
Counterterms in Massive Gravity Theory
Cao, Li-Ming
2015-01-01
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.
A new quasidilaton theory of massive gravity (Journal Article...
Office of Scientific and Technical Information (OSTI)
A new quasidilaton theory of massive gravity Citation Details In-Document Search Title: A new quasidilaton theory of massive gravity We present a new quasidilaton theory of...
Ground Gravity Survey At Dixie Valley Geothermal Area (Allis...
Ground Gravity Survey At Dixie Valley Geothermal Area (Allis, Et Al., 2000) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey...
Ground Gravity Survey At Roosevelt Hot Springs Geothermal Area...
Ground Gravity Survey At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity...
Hamiltonian analysis of self-dual gauge gravity
Steven Kerr
2015-04-15
The Hamiltonian analysis of the self-dual gauge gravity theory is carried out. The resulting canonical structure is equivalent to that of self-dual gravity.
Ground Gravity Survey At Neal Hot Springs Geothermal Area (Colwell...
Ground Gravity Survey At Neal Hot Springs Geothermal Area (Colwell, Et Al., 2012) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity...
Ground Gravity Survey At Lake City Hot Springs Area (Warpinski...
Ground Gravity Survey At Lake City Hot Springs Area (Warpinski, Et Al., 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity...
Ground Gravity Survey At Under Steamboat Springs Area (Warpinski...
Ground Gravity Survey At Under Steamboat Springs Area (Warpinski, Et Al., 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (FURUMOTO...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (FURUMOTO, 1976) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (Leslie...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (Leslie, Et Al., 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (Broyles...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (Broyles, Et Al., 1979) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity...
Integration of Full Tensor Gravity and ZTEM Passive Low Frequency...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Full Tensor Gravity and ZTEM Passive Low Frequency EM Instruments for Simultaneous Data Acquisition Integration of Full Tensor Gravity and ZTEM Passive Low Frequency EM Instruments...
Gravity in Complex Hermitian Space-Time
Ali H. Chamseddine
2006-10-09
A generalized theory unifying gravity with electromagnetism was proposed by Einstein in 1945. He considered a Hermitian metric on a real space-time. In this work we review Einstein's idea and generalize it further to consider gravity in a complex Hermitian space-time.
Horava-Lifshitz gravity with detailed balance
Daniele Vernieri; Thomas P. Sotiriou
2012-12-18
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.
Gravity Capillary Standing Water Waves Pietro Baldi
Thomann, Laurent
Gravity Capillary Standing Water Waves Pietro Baldi Universit`a di Napoli Federico II Joint work with Thomas Alazard (ENS Paris) Pienza, 29 October 2014 Pietro Baldi Gravity Capillary Standing Water Waves construct small amplitude, standing solutions of Sobolev reg. (standing := periodic in time and space
Naked singularities and quantum gravity
Harada, Tomohiro; Iguchi, Hideo; Nakao, Ken-ichi; Singh, T. P.; Tanaka, Takahiro; Vaz, Cenalo
2001-08-15
There are known models of spherical gravitational collapse in which the collapse ends in a naked shell-focusing singularity for some initial data. If a massless scalar field is quantized on the classical background provided by such a star, it is found that the outgoing quantum flux of the scalar field diverges in the approach to the Cauchy horizon. We argue that the semiclassical approximation (i.e., quantum field theory on a classical curved background) used in these analyses ceases to be valid about one Planck time before the epoch of naked singularity formation, because by then the curvature in the central region of the star reaches the Planck scale. It is shown that during the epoch in which the semiclassical approximation is valid, the total emitted energy is about one Planck unit, and is not divergent. We also argue that back reaction in this model does not become important so long as gravity can be treated classically. It follows that the further evolution of the star will be determined by quantum gravitational effects, and without invoking quantum gravity it is not possible to say whether the star radiates away on a short time scale or settles down into a black hole state.
Solar System constraints to nonminimally coupled gravity
Orfeu Bertolami; Riccardo March; Jorge Páramos
2013-06-05
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.
*Corresponding author, E-mail: ndelucca@nd.edu The Airborne Aero-Optics Laboratory, Recent Data
Gordeyev, Stanislav
*Corresponding author, E-mail: ndelucca@nd.edu The Airborne Aero-Optics Laboratory, Recent Data, Notre Dame, IN USA 46556 ABSTRACT In this paper recent in-flight aero-optical measurements on the Airborne Aero-Optics Laboratory (AAOL) will be given. Instrumentation and experimental set
Christopher, Sundar A.
Airborne Sun photometer measurements of aerosol optical depth and columnar water vapor during to within 0.0040.030 with coincident data obtained with an AERONET Sun/ sky radiometer located on Cabras Dynamics: Remote sensing; KEYWORDS: PRIDE, airborne Sun photometer, aerosol optical depth, columnar water
Preliminary calculations on direct heating of a containment atmosphere by airborne core debris
Pilch, M.; Tarbell, W.W.
1986-07-01
Direct heating of the containment atmosphere by airborne core debris may be a significant source of containment pressurization in those accident sequences where the primary system is still at high pressure when the RPV fails. Vigorous blowdown of the primary system may result in nearly complete relocation of core debris out of the reactor cavity and possibly into the containment atmosphere where the liberation of thermal and chemical energy can directly heat the atmosphere. Rate independent and rate dependent models are developed and exercised parametrically to quantify the possible magnitude and rate of containment pressurization from direct heating. The possible mitigative effects of airborne water and subcompartment heating are also investigated.
Frazier, T.P.
1995-12-01
This Quality Assurance Project Plan addresses the quality assurance requirements for compiling Hanford Site radioactive airborne emissions data. These data will be reported to the U.S. Environmental Protection Agency, the US Department of Energy, and the Washington State Department of Health. Effluent Monitoring performs compliance assessments on radioactive airborne sampling and monitoring systems. This Quality Assurance Project Plan is prepared in compliance with interim guidelines and specifications. Topics include: project description; project organization and management; quality assurance objectives; sampling procedures; sample custody; calibration procedures; analytical procedures; monitoring and reporting criteria; data reduction, verification, and reporting; internal quality control; performance and system audits; corrective actions; and quality assurance reports.
The Necessity of Quantizing Gravity
Adelman, Jeremy
2015-01-01
The Eppley Hannah thought experiment is often cited as justification for attempts by theorists to develop a complete, consistent theory of quantum gravity. A modification of the earlier "Heisenberg microscope" argument for the necessity of quantized light, the Eppley-Hannah thought experiment purports to show that purely classical gravitational waves would either not conserve energy or else allow for violations of the uncertainty principle. However, several subsequent papers have cast doubt as to the validity of the Eppley-Hannah argument. In this paper, we attempt to resurrect the Eppley-Hannah thought experiment by modifying the original argument in such a manner as to render it immune to the present criticisms levied against it.
A parametrix for quantum gravity?
Esposito, Giampiero
2015-01-01
In the sixties, DeWitt discovered that the advanced and retarded Green functions of the wave operator on metric perturbations in the de Donder gauge make it possible to define classical Poisson brackets on the space of functionals that are invariant under the action of the full diffeomorphism group of spacetime. He therefore tried to exploit this property to define invariant commutators for the quantized gravitational field, but the operator counterpart of such classical Poisson brackets turned out to be a hard task. On the other hand, the mathematical literature studies often an approximate inverse, the parametrix, which is, strictly, a distribution. We here suggest that such a construction might be exploited in canonical quantum gravity. We begin with the simplest case, i.e. fundamental solution and parametrix for the linear, scalar wave operator; the next step are tensor wave equations, again for linear theory, e.g. Maxwell theory in curved spacetime. Last, the nonlinear Einstein equations are studied, rel...
Dimensional Reduction in Quantum Gravity
G. 't Hooft
2009-03-20
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.
Testing Gravity Using Dwarf Stars
Sakstein, Jeremy
2015-01-01
Generic scalar-tensor theories of gravity predict deviations from Newtonian physics inside astrophysical bodies. In this paper, we point out that low mass stellar objects, red and brown dwarf stars, are excellent probes of these theories. We calculate two important and potentially observable quantities: the radius of brown dwarfs and the minimum mass for hydrogen burning in red dwarfs. The brown dwarf radius can differ significantly from the GR prediction and upcoming surveys that probe the mass-radius relation for stars with masses $hydrogen burning can be larger than several presently observed Red Dwarf stars. This places a new and extremely stringent constraint on the parameters that appear in the effective field theory of dark energy and rules out several well-studied dark energy models.
Testing Gravity Using Dwarf Stars
Jeremy Sakstein
2015-11-05
Generic scalar-tensor theories of gravity predict deviations from Newtonian physics inside astrophysical bodies. In this paper, we point out that low mass stellar objects, red and brown dwarf stars, are excellent probes of these theories. We calculate two important and potentially observable quantities: the radius of brown dwarfs and the minimum mass for hydrogen burning in red dwarfs. The brown dwarf radius can differ significantly from the GR prediction and upcoming surveys that probe the mass-radius relation for stars with masses $hydrogen burning can be larger than several presently observed Red Dwarf stars. This places a new and extremely stringent constraint on the parameters that appear in the effective field theory of dark energy and rules out several well-studied dark energy models.
Tom Fleming; Mark Gross; Ray Renken
1994-01-04
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
2013-07-07
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.
Gravity as BF theory plus potential
Kirill Krasnov
2009-07-23
Spin foam models of quantum gravity are based on Plebanski's formulation of general relativity as a constrained BF theory. We give an alternative formulation of gravity as BF theory plus a certain potential term for the B-field. When the potential is taken to be infinitely steep one recovers general relativity. For a generic potential the theory still describes gravity in that it propagates just two graviton polarizations. The arising class of theories is of the type amenable to spin foam quantization methods, and, we argue, may allow one to come to terms with renormalization in the spin foam context.
Ning Wu
2012-07-11
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
2013-01-01
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
2011-01-01
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.
Penarrubia, Jorge; Walker, Matthew G.
2012-11-20
We introduce the Minimum Entropy Method, a simple statistical technique for constraining the Milky Way gravitational potential and simultaneously testing different gravity theories directly from 6D phase-space surveys and without adopting dynamical models. We demonstrate that orbital energy distributions that are separable (i.e., independent of position) have an associated entropy that increases under wrong assumptions about the gravitational potential and/or gravity theory. Of known objects, 'cold' tidal streams from low-mass progenitors follow orbital distributions that most nearly satisfy the condition of separability. Although the orbits of tidally stripped stars are perturbed by the progenitor's self-gravity, systematic variations of the energy distribution can be quantified in terms of the cross-entropy of individual tails, giving further sensitivity to theoretical biases in the host potential. The feasibility of using the Minimum Entropy Method to test a wide range of gravity theories is illustrated by evolving restricted N-body models in a Newtonian potential and examining the changes in entropy introduced by Dirac, MONDian, and f(R) gravity modifications.
Christian, Joshua M.; Ho, Clifford Kuofei
2010-04-01
Understanding the effects of gravity and wind loads on concentrating solar power (CSP) collectors is critical for performance calculations and developing more accurate alignment procedures and techniques. This paper presents a rigorous finite-element model of a parabolic trough collector that is used to determine the impact of gravity loads on bending and displacements of the mirror facets and support structure. The geometry of the LUZ LS-2 parabolic trough collector was modeled using SolidWorks, and gravity-induced loading and displacements were simulated in SolidWorks Simulation. The model of the trough collector was evaluated in two positions: the 90{sup o} position (mirrors facing upward) and the 0{sup o} position (mirrors facing horizontally). The slope errors of the mirror facet reflective surfaces were found by evaluating simulated angular displacements of node-connected segments along the mirror surface. The ideal (undeformed) shape of the mirror was compared to the shape of the deformed mirror after gravity loading. Also, slope errors were obtained by comparing the deformed shapes between the 90{sup o} and 0{sup o} positions. The slope errors resulting from comparison between the deformed vs. undeformed shape were as high as {approx}2 mrad, depending on the location of the mirror facet on the collector. The slope errors resulting from a change in orientation of the trough from the 90{sup o} position to the 0{sup o} position with gravity loading were as high as {approx}3 mrad, depending on the location of the facet.
The Airborne Aero-Optics Laboratory, AAOL Eric J. Jumpera1
Gordeyev, Stanislav
The Airborne Aero-Optics Laboratory, AAOL Eric J. Jumpera1 , Mike Zenka , Stanislav Gordeyeva Abstract This paper gives a background into aero-optics which is the effect that turbulent flow over discusses the magnitude of the detrimental effects that aero-optics has on optical system performance
Tessier, Russell
of Massachusetts (UMass) to study ocean surface waves and currents in coastal regions. This airborne radar operates. Over several years, DBI was flown on a National Oceanic and Atmospheric Administration's WP-3D research aircraft in a number of successful missions collecting the data both over land and ocean. These deployments
Flight Test Evaluation of a Prototype Optical Instrument for Airborne Sense-and-Avoid Applications
Hornsey, Richard
Flight Test Evaluation of a Prototype Optical Instrument for Airborne Sense-and-Avoid Applications sense-and-avoid instrument was constructed from low-cost commercial off-the- shelf components 205 and the Bell 206 (intruder aircraft) were fully instrumented to record position and orientation
Bohannan, Brendan
, is an energy-efficient way to simultaneously cool building mass and avoid overnight and weekend microbial an intensive temporal study of indoor airborne bacterial communities in a high-traffic university building associated with differing ventilation strategies relevant to modern building design. Our results indicate
One-dimensional inversion of airborne electromagnetic data: application to oil sands exploration
Farquharson, Colin G.
One-dimensional inversion of airborne electromagnetic data: application to oil sands exploration, and Larry Mewhort. · Richard Kellett, formerly of Komex International. #12;Oil sands in Canada #12;Source: Mark Savage, "Oil Sands Characteristics - Geology," 9 April 2002 Wabasca Calgary Edmonton Cold Lake
TOMOGRAPHIC RETRIEVAL OF CLOUD WATER DISTRIBUTIONS USING AN AIR-BORNE SCANNING MICROWAVE RADIOMETER
TOMOGRAPHIC RETRIEVAL OF CLOUD WATER DISTRIBUTIONS USING AN AIR-BORNE SCANNING MICROWAVE RADIOMETER, for United States Government purposes. BNL-79834-2008-AB #12;ABSTRACT Microwave radiometers have been used, but neither the microwave technology nor the cloud models were mature enough for practical application
Effects of particle size and velocity on burial depth of airborne particles in glass fiber filters
Higby, D.P.
1984-11-01
Air sampling for particulate radioactive material involves collecting airborne particles on a filter and then determining the amount of radioactivity collected per unit volume of air drawn through the filter. The amount of radioactivity collected is frequently determined by directly measuring the radiation emitted from the particles collected on the filter. Counting losses caused by the particle becoming buried in the filter matrix may cause concentrations of airborne particulate radioactive materials to be underestimated by as much as 50%. Furthermore, the dose calculation for inhaled radionuclides will also be affected. The present study was designed to evaluate the extent to which particle size and sampling velocity influence burial depth in glass-fiber filters. Aerosols of high-fired /sup 239/PuO/sub 2/ were collected at various sampling velocities on glass-fiber filters. The fraction of alpha counts lost due to burial was determined as the ratio of activity detected by direct alpha count to the quantity determined by photon spectrometry. The results show that burial of airborne particles collected on glass-fiber filters appears to be a weak function of sampling velocity and particle size. Counting losses ranged from 0 to 25%. A correction that assumes losses of 10 to 15% would ensure that the concentration of airborne alpha-emitting radionuclides would not be underestimated when glass-fiber filters are used. 32 references, 21 figures, 11 tables.
Effect of sampling height on the concentration of airborne fungal spores
Levetin, Estelle
and possible sources of air pollution.8 In addition, it is high enough to avoid vandalism and bothering aeroallergens. Airborne fungal spores are commonly collected from the outdoor air at the rooftop level of high respiration level (1.5 m above the ground) and at roof level (12 m height). Methods: Air samples were
Won, Chang-Hee
1 Initial Attitude Estimation of Tactical Grade Inertial Measurement Unit for Airborne alignment depends on the inertial measurement unit's performance. In the case of the tactical grade inertial measurement unit, even though tilt angles can be estimated relatively accurately by using accelerometer
DETECTION OF IMPULSE-LIKE AIRBORNE SOUND FOR DAMAGE IDENTIFICATION IN ROTOR BLADES OF WIND TURBINES
Boyer, Edmond
DETECTION OF IMPULSE-LIKE AIRBORNE SOUND FOR DAMAGE IDENTIFICATION IN ROTOR BLADES OF WIND TURBINES burdens of wind turbines. To detect damage of rotor blades, several research projects focus on an acoustic, rotor blade, wind turbine INTRODUCTION There are several publications of non destructive damage
Statistical Issues in the Study of Air Pollution Involving Airborne Particulate Matter
Washington at Seattle, University of
Statistical Issues in the Study of Air Pollution Involving Airborne Particulate Matter Lawrence H which provides the Center's primary funding. #12;1 STATISTICAL ISSUES IN THE STUDY OF AIR POLLUTION.S. cities. This and other scientific and policy information formed the basis on which the U.S. Environmental
Measurement of airborne radioactivity from the Fukushima reactor accident in Tokushima, Japan
K. Fushimi; S. Nakayama; M. Sakama; Y. Sakaguchi
2012-10-19
The airborne radioactive isotopes from the Fukushima Daiichi nuclear plan t was measured in Tokushima, western Japan. The continuous monitoring has been carried out in Tokushima. From March 23, 2011 the fission product $^{131}$I was observed. The radioisotopes $^{134}$Cs and $^{137}$Cs were also observed in the beginning of April. However the densities were extremely smaller than the Japanese regulation of radioisotopes.
Mali 2006/2007 Airborne Measurements (Mali 2006/2007 Mesures Aroportes)
Delene, David J.
Mali 2006/2007 Airborne Measurements (Mali 2006/2007 Mesures AĂ©roportĂ©es) #12;Measurement Objectives (Objectifs De Mesure) Determine if cloud seeding in Mali could be beneficial. (DĂ©terminer si l'ensemencement des nuages au Mali pourrait ĂŞtre bĂ©nĂ©fique.) Help determine what is the optimal seeding method
Airborne thermal remote sensing for water temperature assessment in rivers and streams
Brown, Sally
). Stream temperature monitoring presents challenges for water resource managers charged with the taskAirborne thermal remote sensing for water temperature assessment in rivers and streams Christian E are needed to assess spatial patterns of stream temperature at scales relevant to issues in water quality
Computational Concerns in the Integration of Unmanned Airborne Systems into Controlled Airspace
Johnson, Chris
], as well as EUROCONTROL's Spec-0102 on the Use of Military Unmanned Aerial Vehicles as Operational Air safeguards. Within the US military funding for Unmanned Airborne Vehicles (UAVs) development has increased London Olympics. A new generation of unmanned freight vehicles is being deployed to help the US military
Farrell, Brian F.
Gravity Waves in a Horizontal Shear Flow. Part II: Interaction between Gravity Waves and Potential perturbations and propagating internal gravity waves in a horizon- tally sheared zonal flow is investigated. In the strong stratification limit, an initial vorticity perturbation weakly excites two propagating gravity
National Airborne Field Experiments for Prediction in Ungauged Basins
Walker, Jeff
, such as validation of these data products from new sensors, maturing retrieval algorithms, developing techniques with thermal infrared, near infrared, visible and lidar data. Passive microwave data will be collected in both if there is sufficient interest. A trial campaign to evalu
Antimatter-Gravity Couplings, and Lorentz Symmetry
Jay D. Tasson
2015-01-27
Implications of possible CPT and Lorentz violation for antimatter-gravity experiments as well as other antimatter tests are considered in the context of the general field-theory-based framework of the Standard-Model Extension (SME).
Asymptotic safety of gravity-matter systems
Meibohm, Jan; Reichert, Manuel
2015-01-01
We study the ultraviolet stability of gravity-matter systems for general numbers of minimally coupled scalars and fermions. This is done within the functional renormalisation group setup put forward in \\cite{Christiansen:2015rva} for pure gravity. It includes full dynamical propagators and a genuine dynamical Newton's coupling, which is extracted from the graviton three-point function. We find ultraviolet stability of general gravity-fermion systems. Gravity-scalar systems are also found to be ultraviolet stable within validity bounds for the chosen generic class of regulators, based on the size of the anomalous dimension. Remarkably, the ultraviolet fixed points for the dynamical couplings are found to be significantly different from those of their associated background counterparts, once matter fields are included. In summary, the asymptotic safety scenario does not put constraints on the matter content of the theory within the validity bounds for the chosen generic class of regulators.
Quantum gravity and renormalization: The tensor track
Rivasseau, Vincent
2012-06-27
We propose a new program to quantize and renormalize gravity based on recent progress on the analysis of large random tensors. We compare it briefly with other existing approaches.
Energy conditions in f(R)-gravity
J. Santos; J. S. Alcaniz; M. J. Reboucas; F. C. Carvalho
2007-09-06
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
2013-02-05
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. $\
A new vacuum for Loop Quantum Gravity
Bianca Dittrich; Marc Geiller
2015-05-05
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.
Gravity waves from vortex dipoles and jets
Wang, Shuguang
2009-05-15
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...
Primordial Density Fluctuations in Phase Coupling Gravity
C. E. M. Batista; M. Schiffer
1996-01-10
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.
Oblique reflections of internal gravity wave beams
Karimi, Hussain H. (Hussain Habibullah)
2012-01-01
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 ...
Emergence in Holographic Scenarios for Gravity
Dennis Dieks; Jeroen van Dongen; Sebastian de Haro
2015-09-10
'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 gravity there as well.
Brane worlds in gravity with auxiliary fields
Bin Guo; Yu-Xiao Liu; Ke Yang
2015-03-11
Recently, Pani, Sotiriou, and Vernieri explored a new theory of gravity by adding nondynamical fields, i.e., gravity with auxiliary fields [Phys. Rev. D 88, 121502(R) (2013)]. In this gravity theory, higher-order derivatives of matter fields generically appear in the field equations. In this paper we extend this theory to any dimensions and discuss the thick braneworld model in five dimensions. Domain wall solutions are obtained numerically. The stability of the brane system under the tensor perturbation is analyzed. We find that the system is stable under the tensor perturbation and the gravity zero mode is localized on the brane. Therefore, the four-dimensional Newtonian potential can be realized on the brane.
Gravity waves from cosmic bubble collisions
Salem, Michael P.; Saraswat, Prashant; Shaghoulian, Edgar E-mail: ps88@stanford.edu
2013-02-01
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.
Green's Functions in Perturbative Quantum Gravity
Sudhaker Upadhyay; Bhabani Prasad Mandal
2015-04-03
We show that the Green's functions in non-linear gauge in the theory of perturbative quantum gravity is expressed as a series in terms of those in linear gauges. This formulation is also holds for operator Green's functions. We further derive the explicit relation between the Green's functions in the theory of perturbative quantum gravity in a pair of arbitary gauges. This process involves some sort of modified FFBRST transformations which is derivable from infinitesimal field-dependent BRST transformations.
Anisotropic induced gravity and inflationary universe
W. F. Kao
2006-12-09
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.
Analogue gravity in hyperbolic metamaterials
Igor I. Smolyaninov
2013-09-09
Sub-wavelength confinement of light in nonlinear hyperbolic metamaterials due to formation of spatial solitons has attracted much recent attention because of its seemingly counter-intuitive behavior. In order to achieve self-focusing in a hyperbolic wire medium, a nonlinear self-defocusing Kerr medium must be used as a dielectric host. Here we demonstrate that this behavior finds natural explanation in terms of analogue gravity. Wave equation describing propagation of extraordinary light inside hyperbolic metamaterials exhibits 2+1 dimensional Lorentz symmetry. The role of time in the corresponding effective 3D Minkowski spacetime is played by the spatial coordinate aligned with the optical axis of the metamaterial. Nonlinear optical Kerr effect bends this spacetime resulting in effective gravitational force between extraordinary photons. In order for the effective gravitational constant to be positive, negative self-defocusing Kerr medium must be used as a host. If gravitational self-interaction is strong enough, spatial soliton may collapse into a black hole analogue.
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.
2015-05-29
The gravitational acceleration of antimatter, Żg, 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 Żg 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
Measuring antimatter gravity with muonium
Kaplan, Daniel M.; Kirch, Klaus; Mancini, Derrick; Phillips, James D.; Phillips, Thomas J.; Roberts, Thomas J.; Terry, Jeff; Bravina, L.; Foka, Y.; Kabana, S.
2015-05-29
The gravitational acceleration of antimatter, Żg, 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 nm grating pitch, a 10% measurement of Żg 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.
Nonderivative modified gravity: a classification
Comelli, D.; Nesti, F.; Pilo, L. E-mail: fabrizio.nesti@irb.hr
2014-11-01
We analyze the theories of gravity modified by a generic nonderivative potential built from the metric, under the minimal requirement of unbroken spatial rotations. Using the canonical analysis, we classify the potentials V according to the number of degrees of freedom (DoF) that propagate at the nonperturbative level. We then compare the nonperturbative results with the perturbative DoF propagating around Minkowski and FRW backgrounds. A generic V implies 6 propagating DoF at the non-perturbative level, with a ghost on Minkowski background. There exist potentials which propagate 5 DoF, as already studied in previous works. Here, no V with unbroken rotational invariance admitting 4 DoF is found. Theories with 3 DoF turn out to be strongly coupled on Minkowski background. Finally, potentials with only the 2 DoF of a massive graviton exist. Their effect on cosmology is simply equivalent to a cosmological constant. Potentials with 2 or 5 DoF and explicit time dependence appear to be a further viable possibility.
Bimetric gravity and dark matter
Laura Bernard; Luc Blanchet; Lavinia Heisenberg
2015-07-10
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.
Stargate: Energy Management Techniques
Vijay Raghunathan; Mani Srivastava; Trevor Pering; Roy Want
2004-01-01
Stargate: Energy Management Techniques Vijay Raghunathan,Platform specific energy management is crucial for longSolution: System level energy management techniques and
A Kinetic Theory Approach to Quantum Gravity
B. L. Hu
2002-04-22
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).
Weitz, Lesley Anne
2005-11-01
Research Center (LaRC) in Hampton, Virginia, two parallel research efforts have focusedon terminal area research: one is Airborne Precision Spacing (APS), and the other is the Quiet Aircraft Technologies (QAT) project. The APS objective is to increase...
Fortner, Edward Charles
2009-05-15
Measurements of ambient volatile organic compounds (VOCs) by proton transfer reaction mass spectrometry (PTR-MS) are reported from recent airborne and surface based field campaigns. The Southeast Texas Tetroon Study (SETTS) ...
Oliva, Sergio Eduardo
2003-01-01
The purpose of this thesis is to develop a method for assessing airborne concentrations caused by off-target pesticide drift. Concentrations are bounded by the worst credible circumstances within a normal aircraft pesticide spraying. It is assumed...
Clarke, Antony
and 6 km over Sagami Bay southwest of Tokyo. The C-130 observation package included a tracking Sun extinction coefficients (sa $ 0.03 kmŔ1 ) derived from the airborne tracking Sun photometer, in situ optical
Jones, Melody Louise
1982-01-01
AIRBORNE RADIOACTIVE MATERIAL COLLECTION, MEASUREMENT, AND DATA STORAGE FOR THE NUCLEAR SCIENCE CENTER AT TEXAS A&M UNIVERSITY A Thesis by MELODY LOUISE JONES Submitted to the Graduate College of Texas A&M University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE August 1982 Major Subject: Nuclear Engineering AIRBORNE RADIOACTIVE MATERIAL COLLECTION& MEASUREMENT& AND DATA STORAGE FOR THE NUCLEAR SCIENCE CENTER AT TEXAS A&M UNIVERSITY A Thesis by MELODY LOUISE...
AIR INFILTRATION MEASUREMENT TECHNIQUES
Sherman, M.H.
2013-01-01
serious study of research problems in infiltration. THEORYInfiltration Measurement Techniques REFERENCES J .B. Dick, "Experimental Studies
Review on the quantization of gravity
Benjamin Schulz
2014-09-29
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.
Neutron stars: compact objects with relativistic gravity
Ek?i, K Yavuz
2015-01-01
General properties of neutron stars are briefly reviewed with an emphasis on the indispensability of general relativity in our understanding of these fascinating objects. In Newtonian gravity the pressure within a star merely plays the role of opposing self-gravity. In general relativity all sources of energy and momentum contribute to the gravity. As a result the pressure not only opposes gravity but also enhances it. The later role of pressure becomes more pronounced with increasing compactness, $M/R$ where $M$ and $R$ are the mass and radius of the star, and sets a critical mass beyond which collapse is inevitable. This critical mass has no Newtonian analogue; it is conceptually different than the Stoner-Landau-Chandrasekhar limit in Newtonian gravity which is attained asymptotically for ultra-relativistic fermions. For white dwarfs the general relativistic critical mass is very close to the Stoner-Landau-Chandrasekhar limit. For neutron stars the maximum mass---so called Oppenheimer-Volkoff limit---is sig...
Massive gravity wrapped in the cosmic web
Shim, Junsup; Lee, Jounghun; Li, Baojiu E-mail: jounghun@astro.snu.ac.kr
2014-03-20
We study how the filamentary pattern of the cosmic web changes if the true gravity deviates from general relativity (GR) on a large scale. The f(R) gravity, whose strength is controlled to satisfy the current observational constraints on the cluster scale, is adopted as our fiducial model and a large, high-resolution N-body simulation is utilized for this study. By applying the minimal spanning tree algorithm to the halo catalogs from the simulation at various epochs, we identify the main stems of the rich superclusters located in the most prominent filamentary section of the cosmic web and determine their spatial extents per member cluster to be the degree of their straightness. It is found that the f(R) gravity has the effect of significantly bending the superclusters and that the effect becomes stronger as the universe evolves. Even in the case where the deviation from GR is too small to be detectable by any other observables, the degree of the supercluster straightness exhibits a conspicuous difference between the f(R) and the GR models. Our results also imply that the supercluster straightness could be a useful discriminator of f(R) gravity from the coupled dark energy since it is shown to evolve differently between the two models. As a final conclusion, the degree of the straightness of the rich superclusters should provide a powerful cosmological test of large scale gravity.
Apparatus for real-time airborne particulate radionuclide collection and analysis
Smart, John E. (West Richland, WA); Perkins, Richard W. (Richland, WA)
2001-01-01
An improved apparatus for collecting and analyzing an airborne particulate radionuclide having a filter mounted in a housing, the housing having an air inlet upstream of the filter and an air outlet downstream of the filter, wherein an air stream flows therethrough. The air inlet receives the air stream, the filter collects the airborne particulate radionuclide and permits a filtered air stream to pass through the air outlet. The improvement which permits real time counting is a gamma detecting germanium diode mounted downstream of the filter in the filtered air stream. The gamma detecting germanium diode is spaced apart from a downstream side of the filter a minimum distance for a substantially maximum counting detection while permitting substantially free air flow through the filter and uniform particulate radionuclide deposition on the filter.
Device and method for accurately measuring concentrations of airborne transuranic isotopes
McIsaac, C.V.; Killian, E.W.; Grafwallner, E.G.; Kynaston, R.L.; Johnson, L.O.; Randolph, P.D.
1996-09-03
An alpha continuous air monitor (CAM) with two silicon alpha detectors and three sample collection filters is described. This alpha CAM design provides continuous sampling and also measures the cumulative transuranic (TRU), i.e., plutonium and americium, activity on the filter, and thus provides a more accurate measurement of airborne TRU concentrations than can be accomplished using a single fixed sample collection filter and a single silicon alpha detector. 7 figs.
Device and method for accurately measuring concentrations of airborne transuranic isotopes
McIsaac, Charles V. (Idaho Falls, ID); Killian, E. Wayne (Idaho Falls, ID); Grafwallner, Ervin G. (Arco, ID); Kynaston, Ronnie L. (Blackfoot, ID); Johnson, Larry O. (Pocatello, ID); Randolph, Peter D. (Idaho Falls, ID)
1996-01-01
An alpha continuous air monitor (CAM) with two silicon alpha detectors and three sample collection filters is described. This alpha CAM design provides continuous sampling and also measures the cumulative transuranic (TRU), i.e., plutonium and americium, activity on the filter, and thus provides a more accurate measurement of airborne TRU concentrations than can be accomplished using a single fixed sample collection filter and a single silicon alpha detector.
Geophex Airborne Unmanned Survey System (GAUSS). Topical report, October 1993--March 1995
1995-03-01
The objectives of the project are to construct a geophysical sensor system based on a remotely operated model helicopter (ROH) and to evaluate the efficacy of the system for characterization of hazardous environmental sites. Geophex Airborne Unmanned Survey System (GAUSS) is a geophysical survey system that uses a ROH as the survey vehicle. We have selected the ROH because of its advantages over fixed wing and ground based vehicles. Lower air speed and superior maneuverability of the ROH make it better suited for geophysical surveys than a fixed wing model aircraft. The ROH can fly close to the ground, allowing detection of weak or subtle anomalies. Unlike ground based vehicles, the ROH can traverse difficult terrain while providing a stable sensor platform. ROH does not touch the ground during the course of a survey and is capable of functioning over water and surf zones. The ROH has been successfully used in the motion picture industry and by geology companies for payload bearing applications. The only constraint to use of the airborne system is that the ROH must remain visible to the pilot. Obstructed areas within a site can be characterized by relocating the base station to alternate positions. GAUSS consists of a ROH with radio controller, a data acquisition and processing (DAP) system, and lightweight digital sensor systems. The objective of our Phase I research was to develop a DAP and sensors suitable for ROH operation. We have constructed these subsystems and integrated them to produce an automated, hand-held geophysical surveying system, referred to as the ``pre-prototype``. We have performed test surveys with the pre-prototype to determine the functionality of the and DAP and sensor subsystems and their suitability for airborne application. The objective of the Phase II effort will be to modify the existing subsystems and integrate them into an airborne prototype. Efficacy of the prototype for geophysical survey of hazardous sites will then be determined.
Geophysical Techniques for Monitoring CO2 Movement During Sequestration
Erika Gasperikova; G. Michael Hoversten
2005-11-15
The relative merits of the seismic, gravity, and electromagnetic (EM) geophysical techniques are examined as monitoring tools for geologic sequestration of carbon dioxide (CO{sub 2}). This work does not represent an exhaustive study, but rather demonstrates the capabilities of a number of geophysical techniques for two synthetic modeling scenarios. The first scenario represents combined CO{sub 2} enhanced oil recovery (EOR) and sequestration in a producing oil field, the Schrader Bluff field on the north slope of Alaska, USA. EOR/sequestration projects in general and Schrader Bluff in particular represent relatively thin injection intervals with multiple fluid components (oil, hydrocarbon gas, brine, and CO{sub 2}). This model represents the most difficult end member of a complex spectrum of possible sequestration scenarios. The time-lapse performance of seismic, gravity, and EM techniques are considered for the Schrader Bluff model. The second scenario is a gas field that in general resembles conditions of Rio Vista reservoir in the Sacramento Basin of California. Surface gravity, and seismic measurements are considered for this model.
Astrophysical black holes in screened modified gravity
Davis, Anne-Christine; Jha, Rahul; Muir, Jessica; Gregory, Ruth E-mail: r.a.w.gregory@durham.ac.uk E-mail: jlmuir@umich.edu
2014-08-01
Chameleon, environmentally dependent dilaton, and symmetron gravity are three models of modified gravity in which the effects of the additional scalar degree of freedom are screened in dense environments. They have been extensively studied in laboratory, cosmological, and astrophysical contexts. In this paper, we present a preliminary investigation into whether additional constraints can be provided by studying these scalar fields around black holes. By looking at the properties of a static, spherically symmetric black hole, we find that the presence of a non-uniform matter distribution induces a non-constant scalar profile in chameleon and dilaton, but not necessarily symmetron gravity. An order of magnitude estimate shows that the effects of these profiles on in-falling test particles will be sub-leading compared to gravitational waves and hence observationally challenging to detect.
Charged black holes in generalized teleparallel gravity
Rodrigues, M.E.; Houndjo, M.J.S.; Tossa, J.; Momeni, D.; Myrzakulov, R. E-mail: sthoundjo@yahoo.fr E-mail: d.momeni@yahoo.com
2013-11-01
In this paper we investigate charged static black holes in 4D for generalized teleparallel models of gravity, based on torsion as the geometric object for describing gravity according to the equivalence principle. As a motivated idea, we introduce a set of non-diagonal tetrads and derive the full system of non linear differential equations. We prove that the common Schwarzschild gauge is applicable only when we study linear f(T) case. We reobtain the Reissner-Nordstrom-de Sitter (or RN-AdS) solution for the linear case of f(T) and perform a parametric cosmological reconstruction for two nonlinear models. We also study in detail a type of the no-go theorem in the framework of this modified teleparallel gravity.
Fermion Doubling in Loop Quantum Gravity
Jacob Barnett; Lee Smolin
2015-07-05
In this paper, we show that the Hamiltonian approach to loop quantum gravity has a fermion doubling problem. To obtain this result, we couple loop quantum gravity to a free massless scalar and a chiral fermion field, gauge fixing the many fingered time gauge invariance by interpreting the scalar field as a physical clock. We expand around a quantum gravity state based on a regular lattice and consider the limit where the bare cosmological constant is large but the fermonic excitations have energies low in Planck units. We then make the case for identifying the energy spectrum in this approximation with that of a model of lattice fermion theory which is known to double.
Quantum gravity effects in the Kerr spacetime
Reuter, M.; Tuiran, E.
2011-02-15
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.
Solar System Constraints on Disformal Gravity Theories
Hiu Yan Ip; Jeremy Sakstein; Fabian Schmidt
2015-10-15
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
2010-02-04
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.
Solar System Constraints on Disformal Gravity Theories
Ip, Hiu Yan; Schmidt, Fabian
2015-01-01
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.
Gravity tests and the Pioneer anomaly
Marc-Thierry Jaekel; Serge Reynaud
2005-11-04
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
2015-07-02
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.
Gamma-analysis of airborne particulates sampled in Youzhno-Sakhalinsk town at March - April 2011
Tertyshnik, E G; Andreev, F A; Artemyev, G B
2012-01-01
The experience of discovery of the radioactive products which have released into atmosphere of Sakhalin region from Fukushima Daiichi accident is presented. Sampling of airborne particulates and atmosphere fallout was carried out by means of the air ventilation set and horizontal gauze planchs, respectively. The HPGe detector was used for gamma analyses of the airborne samples. Since 23 March we confidently measured 131I in the airborne samples, after 03.04.2011 we also registered a rise of activity 137Cs and 134Cs. 132Te and 132I were discovered in ashen sample of the planch, which had exposed in Youzhno-Kurilk from 14 to 17 March. The effect of the pairs production when in the samples 208Tl presence, which emits gamma-quanta of 2615 keV, causes a rise in apparatus spectra of the peak corresponding to energy 1593 keV, which could be in error ascribed to 140La. It had been experimentally shown that the systematic reduction of 134Cs content in measuring samples due to effect of gamma - gamma coincidence did no...
Gamma-analysis of airborne particulates sampled in Youzhno-Sakhalinsk town at March - April 2011
E. G. Tertyshnik; V. P. Martynenko; F. A. Andreev; G. B. Artemyev
2012-03-22
The experience of discovery of the radioactive products which have released into atmosphere of Sakhalin region from Fukushima Daiichi accident is presented. Sampling of airborne particulates and atmosphere fallout was carried out by means of the air ventilation set and horizontal gauze planchs, respectively. The HPGe detector was used for gamma analyses of the airborne samples. Since 23 March we confidently measured 131I in the airborne samples, after 03.04.2011 we also registered a rise of activity 137Cs and 134Cs. 132Te and 132I were discovered in ashen sample of the planch, which had exposed in Youzhno-Kurilk from 14 to 17 March. The effect of the pairs production when in the samples 208Tl presence, which emits gamma-quanta of 2615 keV, causes a rise in apparatus spectra of the peak corresponding to energy 1593 keV, which could be in error ascribed to 140La. It had been experimentally shown that the systematic reduction of 134Cs content in measuring samples due to effect of gamma - gamma coincidence did not exceed 7 % (for the detector and geometry of the measurement used).
AIRBORNE, OPTICAL REMOTE SENSING OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION
Jerry Myers
2003-11-12
Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. This second six-month technical report summarizes the progress made towards defining, designing, and developing the hardware and software segments of the airborne, optical remote methane and ethane sensor. The most challenging task to date has been to identify a vendor capable of designing and developing a light source with the appropriate output wavelength and power. This report will document the work that has been done to identify design requirements, and potential vendors for the light source. Significant progress has also been made in characterizing the amount of light return available from a remote target at various distances from the light source. A great deal of time has been spent conducting laboratory and long-optical path target reflectance measurements. This is important since it helps to establish the overall optical output requirements for the sensor. It also reduces the relative uncertainty and risk associated with developing a custom light source. The data gathered from the optical path testing has been translated to the airborne transceiver design in such areas as: fiber coupling, optical detector selection, gas filters, and software analysis. Ophir will next, summarize the design progress of the transceiver hardware and software development. Finally, Ophir will discuss remaining project issues that may impact the success of the project.
AIRBORNE, OPTICAL REMOTE SENSING OF METHANE AND ETHANE FOR NATURAL GAS PIPLINE LEAK DETECTION
Jerry Myers
2004-05-12
Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. The third six-month technical report contains a summary of the progress made towards finalizing the design and assembling the airborne, remote methane and ethane sensor. The vendor has been chosen and is on contract to develop the light source with the appropriate linewidth and spectral shape to best utilize the Ophir gas correlation software. Ophir has expanded upon the target reflectance testing begun in the previous performance period by replacing the experimental receiving optics with the proposed airborne large aperture telescope, which is theoretically capable of capturing many times more signal return. The data gathered from these tests has shown the importance of optimizing the fiber optic receiving fiber to the receiving optic and has helped Ophir to optimize the design of the gas cells and narrowband optical filters. Finally, Ophir will discuss remaining project issues that may impact the success of the project.
The inverse-square law and quantum gravity
Nieto, M.M.; Goldman, T.; Hughes, R.J.
1988-01-01
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)
Correlation Between Precision Gravity and Subsidence Measurements at Cerro Prieto
Zelwer, R.
2010-01-01
PRECISION GRAVITY AND SUBSIDENCE MEASUREMENTS AT CERROPRECISION GRAVITY AND SUBSIDENCE MEASUREMENTS AT CERROn d i c a t e s t h a t subsidence took place. Uost of t h e
Theoretical and experimental study of nonlinear internal gravity wave beams
Tabaei Befrouei, Ali, 1974-
2005-01-01
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 ...
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
Gravity modeling of Cenozoic extensional basins, offshore Vietnam
Mauri, Steven Joseph
1993-01-01
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 and Song Hong - Yinggehai...
Ground Gravity Survey At Baltazor Hot Springs Area (Isherwood...
(Fig. 2) shows a 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...
A Finite Quantum Gravity Field Theory Model
Jorge Alfaro; Pablo González; Ricardo Avila
2011-09-22
We discuss the quantization of Delta gravity, a two symmetric tensors model of gravity. This model, in Cosmology, shows accelerated expansion without a cosmological constant. We present the $\\tilde{\\delta}$ transformation which defines the geometry of the model. Then we show that all delta type models live at one loop only. We apply this to General Relativity and we calculate the one loop divergent part of the Effective Action showing its null contribution in vacuum, implying a finite model. Then we proceed to study the existence of ghosts in the model. Finally, we study the form of the finite quantum corrections to the classical action of the model.
Differential geometry, Palatini gravity and reduction
Capriotti, S.
2014-01-15
The present article deals with a formulation of the so called (vacuum) Palatini gravity as a general variational principle. In order to accomplish this goal, some geometrical tools related to the geometry of the bundle of connections of the frame bundle LM are used. A generalization of Lagrange-Poincaré reduction scheme to these types of variational problems allows us to relate it with the Einstein-Hilbert variational problem. Relations with some other variational problems for gravity found in the literature are discussed.
Cosmological Evidence for Modified Gravity (MOG)
Moffat, J W
2015-01-01
Deviations from the standard $\\Lambda$CDM model motivate an interpretation of early universe cosmology using the Scalar-Tensor-Vector-Gravity (STVG) theory. A constraint analysis carried out by Valentino, Melchiorri and Silk, revealed deviations from the growth of structure predicted by General Relativity, and a lensing anomaly in the angular CMB power spectrum data with a $95\\%$ c.l. The modified gravity (MOG) theory resolves the lensing deviation from the standard model and provides an explanation of the CMB and structure growth data.
Violation of Energy Bounds in Designer Gravity
Thomas Hertog
2006-07-31
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.
Prima Facie Questions in Quantum Gravity
C. J. Isham
1993-10-22
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
2014-03-18
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
2015-01-01
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.
Spacetime, Spin and Gravity Probe B
James M. Overduin
2015-04-22
It is more important than ever to push experimental tests of gravitational theory to the limits of existing technology in both range and sensitivity. This brief review focuses on spin-based tests of General Relativity and their implications for alternative, mostly non-metric theories of gravity motivated by the challenge of unification with the Standard Model of particle physics. The successful detection of geodetic precession and frame-dragging by Gravity Probe B places new constraints on a number of these theories, and increases our confidence in the theoretical mechanisms underpinning current ideas in astrophysics and cosmology.
Energy Distribution in f(R) Gravity
M. Sharif; M. Farasat Shamir
2009-12-18
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.
Holographic superconductors from the massive gravity
Hua Bi Zeng; Jian-Pin Wu
2014-09-24
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.
Hogg, Charlie A. R.; Dalziel, Stuart B.; Huppert, Herbert E.; Imberger, Jörg
2015-01-01
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...
Violation of the Holographic Principle in the Loop Quantum Gravity
Ozan Sarg?n; Mir Faizal
2015-09-01
In this paper, we analyze the holographic principle using loop quantum gravity (LQG). This will be done by analysing a simple quantum mechanical system using polymeric quantization. As the polymeric quantization is the characteristic feature of loop quantum gravity, we will argue that this calculation will indicate the effect on the holographic principle from the loop quantum gravity. Thus, we will be able to explicitly demonstrate the violation of the holographic principle in the loop quantum gravity.
Quantum reduced loop gravity: extension to scalar field
Jakub Bilski; Emanuele Alesci; Francesco Cianfrani
2015-07-02
The quantization of the Hamiltonian for a scalar field is performed in the framework of Quantum Reduced Loop Gravity. We outline how the regularization can be performed by using the analogous tools adopted in full Loop Quantum Gravity and the matrix elements of the resulting operator between basis states are analytic coefficients. These achievements open the way for a consistent analysis of the Quantum Gravity corrections to the classical dynamics of gravity in the presence of a scalar field in a cosmological setting.
M.A. Ebadian, Ph.D.; S.K. Dua, Ph.D., C.H.P.; Hillol Guha, Ph.D.
2001-01-01
During deactivation and decommissioning activities, thermal cutting tools, such as plasma torch, laser, and gasoline torch, are used to cut metals. These activities generate fumes, smoke and particulates. These airborne species of matter, called aerosols, may be inhaled if suitable respiratory protection is not used. Inhalation of the airborne metallic aerosols has been reported to cause ill health effects, such as acute respiratory syndrome and chromosome damage in lymphocytes. In the nuclear industry, metals may be contaminated with radioactive materials. Cutting these metals, as in size reduction of gloveboxes and tanks, produces high concentrations of airborne transuranic particles. Particles of the respirable size range (size < 10 {micro}m) deposit in various compartments of the respiratory tract, the fraction and the site in the respiratory tract depending on the size of the particles. The dose delivered to the respiratory tract depends on the size distribution of the airborne particulates (aerosols) and their concentration and radioactivity/toxicity. The concentration of airborne particulate matter in an environment is dependent upon the rate of their production and the ventilation rate. Thus, measuring aerosol size distribution and generation rate is important for (1) the assessment of inhalation exposures of workers, (2) the selection of respiratory protection equipment, and (3) the design of appropriate filtration systems. Size distribution of the aerosols generated during cutting of different metals by plasma torch was measured. Cutting rates of different metals, rate of generation of respirable mass, as well as the fraction of the released kerf that become respirable were determined. This report presents results of these studies. Measurements of the particles generated during cutting of metal plates with a plasma arc torch revealed the presence of particles with mass median aerodynamic diameters of particles close to 0.2 {micro}m, arising from condensation of vaporized material and subsequent rapid formation of aggregates. Particles of larger size, resulting from ejection of melted material or fragments from the cutting zone, were also observed. This study presents data regarding the metal cutting rate, particle size distribution, and their generation rate, while using different cutting tools and metals. The study shows that respirable particles constitute only a small fraction of the released kerf.
Gravity currents in two-layer stratified media
Flynn, Morris R.
Gravity currents in two-layer stratified media Morris R. Flynn & Alan W.Tan Dept. of Mechanical Engineering, U.Alberta Funding: NSERC #12;· Gravity currents appear over a broad range of time/length scales. (1999), Flynn & Linden (2006),White & Helfrich (2008), Ungarish (2009) Introduction current gravity
Gravity Surface Wave Bifurcation in a Highly Turbulent Swirling Flow
Witten, Thomas A.
Gravity Surface Wave Bifurcation in a Highly Turbulent Swirling Flow Michael Baumer University Gravity Wave 2 3 Measurements 3 4 Mechanical Hardware: Problems and Solutions 5 5 Results 7 6 Conclusions investigated a free-surface gravity wave bifurcation in the large-separation regime, that is, where
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
Assessor Training Assessment Techniques
NVLAP Assessor Training Assessment Techniques: Communication Skills and Conducting an Assessment listener ·Knowledgeable Assessor Training 2009: Assessment Techniques: Communication Skills & Conducting, truthful, sincere, discrete · Diplomatic · Decisive · Selfreliant Assessor Training 2009: Assessment
The Mars Gravity Biosatellite as an innovative partial gravity research platform
Fulford-Jones, Thaddeus R. F
2008-01-01
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 ...
The diffeomorphism algebra approach to quantum gravity
T. A. Larsson
1999-09-13
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.
Topological Black Holes in Quantum Gravity
J. Kowalski-Glikman; D. Nowak-Szczepaniak
2000-07-31
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
2012-12-03
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.
p-wave superconductors in dilaton gravity
ZhongYing Fan
2013-10-08
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\
Ultrasonic hydrometer. [Specific gravity of electrolyte
Swoboda, C.A.
1982-03-09
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.
Topology in 4D simplicial quantum gravity
S. Bilke; Z. Burda; B. Petersson
1996-11-22
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.
Airborne concentrations of asbestos in 71 school buildings
Corn, M.; Crump, K.; Farrar, D.B.; Lee, R.J.; McFee, D.R. (Johns Hopkins Univ., Baltimore, MD (USA))
1991-02-01
A total of 473 air samples from 71 schools scheduled for abatement (328 indoor static samples, 51 personal samples, and 94 outdoor samples) were analyzed by transmission electron microscopy techniques. Six measures of asbestos-in-air concentration were considered: (1) total asbestos structures per cubic centimeter: (2) chrysotile structures per cubic centimeter; (3) amphibole structures per cubic centimeter; (4) structures per cubic centimeter at least 0.5 micron long and at least five times wide; (5) structures per cubic centimeter at least 5 microns long; and (6) structures per cubic centimeter at least 5 microns long and at least 0.2 micron wide. The average concentration of chrysotile structures in indoor air samples was 0.017 structures/cm{sup 3}; the average concentration of amphibole structures was 0.0015 structure/cm{sup 3}. Ninety-five percent of structures found were chrysotile. The average concentrations of all structures were significantly higher indoors than outdoors (P less than 0.001). The average concentration of structures more than 5 microns long indoors was 0.00023 structure/cm{sup 3}. None of the following factors were significantly correlated with asbestos concentrations in air: type of asbestos-containing materials (ACM) present, condition of ACM, accessibility of ACM to students, whether ACM were covered, air flow, or whether sweeping was noted during sample collection. In addition, asbestos-in-air concentrations were not significantly different in different types of schools (high, intermediate or elementary) or in schools constructed in different time periods. Lastly, there was no correlation between the mineral type of asbestos found in the air and the type found in samples of bulk material.
Renormalization of lattice-regularized quantum gravity models I. General considerations
Joshua H. Cooperman
2014-10-21
Lattice regularization is a standard technique for the nonperturbative definition of a quantum theory of fields. Several approaches to the construction of a quantum theory of gravity adopt this technique either explicitly or implicitly. A crucial complement to lattice regularization is the process of renormalization through which a continuous description of the quantum theory arises. I provide a comprehensive conceptual discussion of the renormalization of lattice-regularized quantum gravity models. I begin with a presentation of the renormalization group from the Wilsonian perspective. I then consider the application of the renormalization group in four contexts: quantum field theory on a continuous nondynamical spacetime, quantum field theory on a lattice-regularized nondynamical spacetime, quantum field theory of continuous dynamical spacetime, and quantum field theory of lattice-regularized dynamical spacetime. The first three contexts serve to identify successively the particular issues that arise in the fourth context. These issues originate in the inescability of establishing all scales solely on the basis of the dynamics. While most of this discussion rehearses established knowledge, the attention that I pay to these issues, especially the previously underappreciated role of standard units of measure, is largely novel. I conclude by briefly reviewing past studies of renormalization of lattice-regularized quantum gravity models. In the second paper of this two-part series, I illustrate the ideas presented here by proposing a renormalization group scheme for causal dynamical triangulations.
On the z=4 Horava-Lifshitz Gravity
Rong-Gen Cai; Yan Liu; Ya-Wen Sun
2009-06-04
We consider z=4 Horava-Lifshitz gravity in both 3+1 and 4+1 dimensions. We find black hole solutions in the IR region for a kind of z=4 Horava-Lifshitz gravity which is inherited from the new massive gravity in three dimensions and an analog of the new massive gravity in four dimensions through the quantum inheritance principle. We analyze thermodynamic properties for the black hole solutions for z=4 Horava-Lifshitz gravity. We also write out the Friedmann equation in 3+1 dimensions for cosmological solutions.
Measuring the Earth's gravity field with cold atom interferometers
Olivier Carraz; Christian Siemes; Luca Massotti; Roger Haagmans; Pierluigi Silvestrin
2015-06-12
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.
Geodesic Deviation Equation in $f(T)$ gravity
F. Darabi; M. Mousavi; K. Atazadeh
2015-04-14
In this work, we show that it is possible to study the notion of geodesic deviation equation in $f(T)$ gravity, in spite of the fact that in teleparallel gravity there is no notion of geodesics, and the torsion is responsible for the appearance of gravitational interaction. In this regard, we obtain the GR equivalent equations for $f(T)$ gravity which are in the modified gravity form such as $f(R)$ gravity. Then, we obtain the GDE within the context of this modified gravity. In this way, the obtained geodesic deviation equation will correspond to the $f(T)$ gravity. Eventually, we extend the calculations to obtain the modification of Matting relation.
The picture of the Bianchi I model via gauge fixing in Loop Quantum Gravity
Francesco Cianfrani; Andrea Marchini; Giovanni Montani
2012-01-12
The implications of the SU(2) gauge fixing associated with the choice of invariant triads in Loop Quantum Cosmology are discussed for a Bianchi I model. In particular, via the analysis of Dirac brackets, it is outlined how the holonomy-flux algebra coincides with the one of Loop Quantum Gravity if paths are parallel to fiducial vectors only. This way the quantization procedure for the Bianchi I model is performed by applying the techniques developed in Loop Quantum Gravity but restricting the admissible paths. Furthermore, the local character retained by the reduced variables provides a relic diffeomorphisms constraint, whose imposition implies homogeneity on a quantum level. The resulting picture for the fundamental spatial manifold is that of a cubical knot with attached SU(2) irreducible representations. The discretization of geometric operators is outlined and a new perspective for the super-Hamiltonian regularization in Loop Quantum Cosmology is proposed.
Solubility Classification of Airborne Uranium Products from LWR-Fuel Plants
kalkwarf, D. R.
1980-08-01
Airborne dust samples were obtained from various locations within plants manufacturing fuel elements for light-water reactors, and the dissolution rates of uranium from these samples into simulated lung fluid at 37°C were measured. These measurements were used to classify the solubilities of the samples in terms of the lung clearance model proposed by the International Commission on Radiological Protection. Similar evaluations were performed for samples of pure uranium compounds expected as components in plant dust. The variation in solubility classifications of dust encountered along the fuel production lines is described and correlated with the process chemistry and the solubility classifications of the pure uranium compounds.
ARM Airborne Carbon Measurements VI (ARM-ACME V) Science Plan
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room News Publications Traditional Knowledge Kiosks Barrow, Alaska TropicalStorms7 ARM Airborne
Authors, Various
2012-01-01
3 1st Edition FTN4 OPTIMIZATION TECHNIQUES November 1979O. INTRODUCTION 1. COt1PILER OPTIMIZATIONS 2. SOURCE CODEcode. Most of these optimizations decrease central processor
Junction conditions in extended Teleparallel gravities
De la Cruz-Dombriz, Álvaro; Dunsby, Peter K.S.; Sáez-Gómez, Diego E-mail: peter.dunsby@uct.ac.za
2014-12-01
In the context of extended Teleparallel gravity theories, we address the issue of junction conditions required to guarantee the correct matching of different regions of spacetime. In the absence of shells/branes, these conditions turn out to be more restrictive than their counterparts in General Relativity as in other extended theories of gravity. In fact, the general junction conditions on the matching hypersurfaces depend on the underlying theory and a new condition on the induced tetrads in order to avoid delta-like distributions in the field equations. This result imposes strict consequences on the viability of standard solutions such as the Einstein-Straus-like construction. We find that the continuity of the scalar torsion is required in order to recover the usual General Relativity results.
Hydrogen atom in Palatini theories of gravity
Gonzalo J. Olmo
2008-06-03
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.
Infrared modification of gravity from conformal symmetry
Gegenberg, Jack; Seahra, Sanjeev S
2015-01-01
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.
Conceptual Aspects of Gauge/Gravity Duality
de Haro, Sebastian; Butterfield, Jeremy
2015-01-01
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.
Gravity controlled anti-reverse rotation device
Dickinson, Robert J. (Shaler Township, Allegheny County, PA); Wetherill, Todd M. (Lower Burrell, PA)
1983-01-01
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.
Regulation of flexible arms under gravity
De Luca, A.; Siciliano, B.
1993-08-01
A simple controller is presented for the regulation problem of robot arms with flexible links under gravity. It consists of a joint PD feedback plus a constant feedforward. Global asymptotic stability of the reference equilibrium state is shown under a structural assumption about link elasticity and a mild condition on the proportional gain. The result holds also in the absence of internal damping of the flexible arm. A numerical case study is presented.
Charged Cylindrical Black Holes in Conformal Gravity
Jackson Levi Said; Joseph Sultana; Kristian Zarb Adami
2013-01-04
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.
Holographic Superconductivity with Gauss-Bonnet gravity
Ruth Gregory
2010-12-07
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.
Exact Gravity Dual of a Gapless Superconductor
George Koutsoumbas; Eleftherios Papantonopoulos; George Siopsis
2009-06-17
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.
Disformal Gravity Theories: A Jordan Frame Analysis
Sakstein, Jeremy
2015-01-01
The late-time cosmology of disformal gravity theories is studied in the Jordan frame using both dynamical systems methods, and by finding approximate solutions. We find that, either the disformal effects are irrelevant, or the universe evolves towards a phantom phase where the equation of state of dark energy is $-3$, in strong tension with observations. There is a marginal case where the asymptotic state of the universe depends on the model parameters and de-Sitter solutions can be obtained.
Critical regimes of internal gravity wave generation
Vitaly V. Bulatov; Yuriy V. Vladimirov; Vasily A. Vakorin
2005-11-27
The problem of constructing an asymptotic representation of the solution of the internal gravity wave field exited by a source moving at a velocity close to the maximum group velocity of the individual wave mode is considered. For the critical regimes of individual mode generation the asymptotic representation of the solution obtained is expressed in terms of a zero-order Macdonald function. The results of numerical calculations based on the exact and asymptotic formulas are given.
Neutron stars as laboratories for gravity physics
Deliduman, Cemsinan
2014-01-01
We study the structure of neutron stars in R+?R˛ gravity model with perturbative method. We obtain mass-radius relations for four representative equations of state (EoS). We find that, for |?|~10? cm˛, the results differ substantially from the results of general relativity. The effects of modified gravity are seen as mimicking a stiff or soft EoS for neutron stars depending upon whether ? is negative or positive, respectively. Some of the soft EoS that are excluded within the framework of general relativity can be reconciled for certain values of ? of this order with the 2 solar mass neutron star recently observed. Indeed, if the EoS is ever established to be soft, modified gravity of the sort studied here may be required to explain neutron star masses as large as 2 M{sub ?}. The associated length scale ?(?)~10? cm is of the order of the the typical radius of neutron stars implying that this is the smallest value we could find by using neutron stars as a probe. We thus conclude that the true value of ? is most likely much smaller than 10? cm˛.
Cosmology in general massive gravity theories
Comelli, D.; Nesti, F.; Pilo, L. E-mail: fabrizio.nesti@aquila.infn.it
2014-05-01
We study the cosmological FRW flat solutions generated in general massive gravity theories. Such a model are obtained adding to the Einstein General Relativity action a peculiar non derivative potentials, function of the metric components, that induce the propagation of five gravitational degrees of freedom. This large class of theories includes both the case with a residual Lorentz invariance as well as the case with rotational invariance only. It turns out that the Lorentz-breaking case is selected as the only possibility. Moreover it turns out that that perturbations around strict Minkowski or dS space are strongly coupled. The upshot is that even though dark energy can be simply accounted by massive gravity modifications, its equation of state w{sub eff} has to deviate from -1. Indeed, there is an explicit relation between the strong coupling scale of perturbations and the deviation of w{sub eff} from -1. Taking into account current limits on w{sub eff} and submillimiter tests of the Newton's law as a limit on the possible strong coupling scale, we find that it is still possible to have a weakly coupled theory in a quasi dS background. Future experimental improvements on short distance tests of the Newton's law may be used to tighten the deviation of w{sub eff} form -1 in a weakly coupled massive gravity theory.
Emergent gravity and ether-drift experiments
M. Consoli; L. Pappalardo
2010-05-04
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.
Abelian-Higgs strings in Rastall gravity
Eugenio R. Bezerra de Mello; Julio C. Fabris; Betti Hartmann
2015-04-02
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.
Cosmology with Coupled Gravity and Dark Energy
Ti-Pei Li
2015-01-13
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.
Contamination Control Techniques
EBY, J.L.
2000-05-16
Welcome to a workshop on contamination Control techniques. This work shop is designed for about two hours. Attendee participation is encouraged during the workshop. We will address different topics within contamination control techniques; present processes, products and equipment used here at Hanford and then open the floor to you, the attendees for your input on the topics.
Emergency Response Equipment and Related Training: Airborne Radiological Computer System (Model II)
David P. Colton
2007-02-28
The materials included in the Airborne Radiological Computer System, Model-II (ARCS-II) were assembled with several considerations in mind. First, the system was designed to measure and record the airborne gamma radiation levels and the corresponding latitude and longitude coordinates, and to provide a first overview look of the extent and severity of an accident's impact. Second, the portable system had to be light enough and durable enough that it could be mounted in an aircraft, ground vehicle, or watercraft. Third, the system must control the collection and storage of the data, as well as provide a real-time display of the data collection results to the operator. The notebook computer and color graphics printer components of the system would only be used for analyzing and plotting the data. In essence, the provided equipment is composed of an acquisition system and an analysis system. The data can be transferred from the acquisition system to the analysis system at the end of the data collection or at some other agreeable time.
Not Available
1988-07-01
This manual provides guidance to US Department of Energy (DOE) facilities on the prompt detection of airborne plutonium in the workplace. Information is first given to aid in detection systems that will function effectively in various workplaces. Steps in designing a system are covered: its general requirements, the plotting of workplace sources of plutonium, and methods of determining workplace airflow patterns. Guidance is provided on the proper numbers and locations of probe sites, the orientation of probes for representative sampling, and the mixture of stationary and portable probes. Recommendations for delivery in sampling systems include examination of particle loss and self-absorption problems, methods of eliminating air leakage in the system, and optimization of decontamination capabilities. System flow rate, requirements in a collection medium, burial loss and pressure drop, and prudent frequency of renewing the collection medium are among air sampling considerations covered. After a discussion of controlling airflow and of vacuum sources and system backups, the checkpoints to ensure system reliability are listed. The manual then discusses instrument specifications that provide correct airborne plutonium concentrations and reliably activate alarms. Focusing on the interrelationship of all components, essential factors in instrument reliability are addressed: the regulatory lower limit of detection and performance specifications of detectors and filters, maintenance and calibration requirements, and features of commonly used plutonium air-sampling instruments. Finally, the manual advises on establishing a documentation program to archive and evaluate the performance of a plutonium air-sampling program.
Quantum Gravito-Optics: A Light Route from Semiclassical Gravity to Quantum Gravity
Unnikrishnan, C S
2015-01-01
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
Black Holes in Gauss-Bonnet Gravity's Rainbow
Seyed Hossein Hendi; Mir Faizal
2015-08-08
In this paper, we will generalize the Gauss-Bonnet gravity to an energy dependent Gauss-Bonnet theory of gravity, which we shall call as the Gauss-Bonnet gravity's rainbow. We will also couple this theory to a Maxwell's theory. We will analyze black hole solutions in this energy dependent Gauss-Bonnet gravity's rainbow. We will calculate the modifications to the thermodynamics of black holes in the Gauss-Bonnet's gravity's rainbow. We will demonstrate that even though the thermodynamics of the black holes get modified in the Gauss-Bonnet gravity's rainbow, the first law of thermodynamics still holds for this modified thermodynamics. We will also comment on the thermal stability of the black hole solutions in this theory.
Testing alternative theories of gravity using the Sun
Jordi Casanellas; Paolo Pani; Ilídio Lopes; Vitor Cardoso
2011-10-20
We propose a new approach to test possible corrections to Newtonian gravity using solar physics. The high accuracy of current solar models and new precise observations allow one to constrain corrections to standard gravity at unprecedented levels. Our case study is Eddington-inspired gravity, an attractive modified theory of gravity which results in non-singular cosmology and collapse. The theory is equivalent to standard gravity in vacuum, but it sensibly differs from it within matter, for instance it affects the evolution and the equilibrium structure of the Sun, giving different core temperature profiles, deviations in the observed acoustic modes and in solar neutrino fluxes. Comparing the predictions from a modified solar model with observations, we constrain the coupling parameter of the theory, |kappa_g| < 3x10^5 m^5 s^2 / kg. Our results show that the Sun can be used to efficiently constraint alternative theories of gravity.
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)
2012-10-01
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.
Solar System experiments do not yet veto modified gravity models
Valerio Faraoni
2006-07-05
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.
Action in the Entropic Revolution of Newtonian Gravity
Joakim Munkhammar
2010-05-17
The theory of gravity has undergone somewhat of a revolution lately. Gravity is no longer a fundamental force it seems, but rather an effect of holographic entropy. Building on the works by Jacobsson, Padmanabhan and Verlinde we review the concept of Newtonian gravity as an entropic force and discuss a possible general action approach to Verlinde's theory. We also discuss some open problems and future prospects of Verlinde's approach.
Covariant Symplectic Structure and Conserved Charges of Topologically Massive Gravity
Caner Nazaroglu; Yavuz Nutku; Bayram Tekin
2011-06-07
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.
Lorentz Invariant phenomenological model of quantum gravity: A minimalistic presentation
Bonder, Yuri
2012-08-24
The purpose of this paper is to give a minimalistic and self-contained presentation of a Lorentz Invariant phenomenological model of Quantum Gravity.
Gravity Survey of the Carson Sink - Data and Maps
Faulds, James E.
2013-12-31
A detailed gravity survey was carried out for the entire Carson Sink in western Nevada (Figure 1) through a subcontract to Zonge Engineering, Inc. The Carson Sink is a large composite basin containing three known, blind high?temperature geothermal systems (Fallon Airbase, Stillwater, and Soda Lake). This area was chosen for a detailed gravity survey in order to characterize the gravity signature of the known geothermal systems and to identify other potential blind systems based on the structural setting indicated by the gravity data. Data: Data were acquired at approximately 400, 800, and 1600 meter intervals for a total of 1,243 stations. The project location and station location points are presented in Figure 14. The station distribution for this survey was designed to complete regional gravity coverage in the Carson Sink area without duplication of available public and private gravity coverage. Gravity data were acquired using a Scintrex CG?5 gravimeter and a LaCoste and Romberg (L&R) Model?G gravimeter. The CG?5 gravity meter has a reading resolution of 0.001 milligals and a typical repeatability of less than 0.005 milligals. The L&R gravity meter has a reading resolution of 0.01 milligals and a typical repeatability of 0.02 milligals. The basic processing of gravimeter readings to calculate through to the Complete Bouguer Anomaly was made using the Gravity and Terrain Correction software version 7.1 for Oasis Montaj by Geosoft LTD. Results: The gravity survey of the Carson Sink yielded the following products. Project location and station location map (Figure 14). Complete Bouguer Anomaly @ 2.67 gm/cc reduction density. Gravity Complete Bouguer Anomaly at 2.50 g/cc Contour Map (Figure 15). Gravity Horizontal Gradient Magnitude Shaded Color Contour Map. Gravity 1st Vertical Derivative Color Contour Map. Interpreted Depth to Mesozoic Basement (Figure 16), incorporating drill?hole intercept values. Preliminary Interpretation of Results: The Carson Sink is a complex composite basin with several major depocenters (Figures 15 and 16). Major depocenters are present in the south?central, east?central, and northeastern parts of the basin. The distribution of gravity anomalies suggests a complex pattern of faulting in the subsurface of the basin, with many fault terminations, step?overs, and accommodation zones. The pattern of faulting implies that other, previously undiscovered blind geothermal systems are likely in the Carson Sink. The gravity survey was completed near the end of this project. Thus, more thorough analysis of the data and potential locations of blind geothermal systems is planned for future work.
Cosmological singularities in Born-Infeld determinantal gravity...
Office of Scientific and Technical Information (OSTI)
Cosmological singularities in Born-Infeld determinantal gravity Citation Details In-Document Search This content will become publicly available on December 16, 2015 Title:...
Dynamical stability of Minkowski space in higher order gravity
Petr V. Tretyakov
2015-05-19
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 Neal Hot Springs Geothermal Area (U...
Ground Gravity Survey At Neal Hot Springs Geothermal Area (U.S. Geothermal Inc., 2007) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground...
Geologic interpretation of gravity and magnetic data in the Salida...
Geologic interpretation of gravity and magnetic data in the Salida region, Colorado Jump to: navigation, search OpenEI Reference LibraryAdd to library Report: Geologic...
Unification of Gravity and Electromagnetism II A Geometric Theory
Partha Ghose
2015-02-11
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
1998-03-13
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
2005-11-10
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.
Exercise protocols during short-radius centrifugation for artificial gravity
Edmonds, Jessica Leigh
2008-01-01
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 ...
Bouguer gravity anomalies, depth to bedrock, and shallow temperature...
Bouguer gravity anomalies, depth to bedrock, and shallow temperature in the Humboldt House geothermal area, Pershing County, Nevada Jump to: navigation, search OpenEI Reference...
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...
Probing hybrid modified gravity by stellar motion around Galactic Centre
D. Borka; S. Capozziello; P. Jovanovi?; V. Borka Jovanovi?
2015-04-29
We consider possible signatures for the so called {\\it hybrid gravity} within the Galactic Central Parsec. This modified theory of gravity consists of a superposition of the metric Einstein-Hilbert Lagrangian with an $f(R)$ term constructed {\\it \\`{a} la Palatini } and can be easily reduced to an equivalent scalar-tensor theory. The present analysis is based on the S2 star orbital precession around the massive compact dark object at the Galactic Centre where the simulated orbits in hybrid modified gravity are compared with astronomical observations. These simulations result with strong constraints on the range of hybrid gravity interaction parameter $\\phi_0$ and show that its most probable value, in the case of S2 star, is around -0.0009 to -0.0002. At the same time, we are also able to obtain reliable constrains on the effective mass parameter $m_{\\phi}$ of hybrid modified gravity. Its most probable value, in the case of S2 star, is around -0.0034 to -0.0025. Furthermore, the hybrid gravity potential induces precession of S2 star orbit in the same direction as General Relativity. In previous papers, we considered other types of extended gravities, like metric power law $f(R)\\propto R^n$ gravity, inducing Yukawa and Sanders-like gravitational potentials, but it seems that hybrid gravity is the best among these models to explain different gravitational phenomena at different astronomical scales.
Hydrogen Burning in Low Mass Stars Constrains Alternative Gravity Theories
Jeremy Sakstein
2015-10-30
The most general scalar-tensor theories of gravity predict a weakening of the gravitational force inside astrophysical bodies. There is a minimum mass for hydrogen burning in stars that is set by the interplay of plasma physics and the theory of gravity. We calculate this for alternative theories of gravity, and find that it is always significantly larger than the general relativity prediction. The observation of several low mass Red Dwarf stars therefore rules out a large class of scalar-tensor gravity theories, and places strong constraints on the cosmological parameters appearing in the effective field theory of dark energy.
Hydrogen Burning in Low Mass Stars Constrains Alternative Gravity Theories
Jeremy Sakstein
2015-10-20
The most general scalar-tensor theories of gravity predict a weakening of the gravitational force inside astrophysical bodies. There is a minimum mass for hydrogen burning in stars that is set by the interplay of plasma physics and the theory of gravity. We calculate this for alternative theories of gravity, and find that it is always significantly larger than the general relativity prediction. The observation of several low mass Red Dwarf stars therefore rules out a large class of scalar-tensor gravity theories, and places strong constraints on the cosmological parameters appearing in the effective field theory of dark energy.
Review of Lattice Supersymmetry and Gauge-Gravity Duality
Joseph, Anosh
2015-01-01
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.
Review of Lattice Supersymmetry and Gauge-Gravity Duality
Anosh Joseph
2015-09-04
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.
Ground Gravity Survey At San Francisco Volcanic Field Area (Warpinski...
geologically mapped the target area, obtained rock samples for age dating and mineral chemistry, performed gravity and magnetic surveys, and integrated these results to identify...
Parameterized post-Newtonian limit of Horndeski's gravity theory
Manuel Hohmann
2015-08-20
We present a recent result on the parameterized post-Newtonian (PPN) limit of Horndeski's gravity theory and its consistency with solar system observations.
Hydrogen Burning in Low Mass Stars Constrains Alternative Gravity Theories
Sakstein, Jeremy
2015-01-01
The most general scalar-tensor theories of gravity predict a weakening of the gravitational force inside astrophysical bodies. There is a minimum mass for hydrogen burning in stars that is set by the interplay of plasma physics and the theory of gravity. We calculate this for alternative theories of gravity, and find that it is always significantly larger than the general relativity prediction. The observation of several low mass Red Dwarf stars therefore rules out a large class of scalar-tensor gravity theories, and places strong constraints on the cosmological parameters appearing in the effective field theory of dark energy.
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
Closed formula for the matrix elements of the volume operator in canonical quantum gravity
T. Thiemann
1996-06-29
We derive a closed formula for the matrix elements of the volume operator for canonical Lorentzian quantum gravity in four spacetime dimensions in the continuum in a spin-network basis. We also display a new technique of regularization which is state dependent but we are forced to it in order to maintain diffeomorphism covariance and in that sense it is natural. We arrive naturally at the expression for the volume operator as defined by Ashtekar and Lewandowski up to a state independent factor.
cancer and environmental contaminants, focusing primarily on agricultural chemical exposure assessmentUse of land surface remotely sensed satellite and airborne data for environmental exposure assessment in cancer research SUSAN K. MAXWELLa , JAYMIE R. MELIKERb AND PIERRE GOOVAERTSc a U.S. Geological
Sehmel, G.A.
1982-12-20
A major eruption of Mount St. Helens occurred on May 18, 1980. Subsequently, airborne solid concentrations were measured as a function of time at two sites within the southern edge of the fallout plume about 211 km east of Mount St. Helens. This ash was a source for investigating area-wide resuspension. Rain had a variable effect on decreasing airborne concentrations from resuspension. From 0.5 to 1.5 cm of rain were required to significantly reduce airborne solid concentrations through July. For a more aged resuspension source in September, a rain of 2.0 cm had a negligible effect. A monthly average threshold-wind speed for resuspension was defined as 3.6 m/s. For monthly-average wind speeds less than the threshold wind speed, monthly-average airborne concentrations tended to decrease with time. A decrease was recorded between September and October. For this 4-month time period, the half-life was on the order of 50 days, corresponding to a weathering rate of 5.1 year/sup -1/.
Baum, Bryan A.
A comparison of cloud top heights computed from airborne lidar and MAS radiance data using CO2]. Other studies have compared CO2- slicing cloud heights with those computed from lidar data [Smith in assessing the accuracy of the CO2-slicing cloud height algorithm. Infrared measurements of upwelling
and Yaoguo Li, Center for Gravity, Electrical and Magnetic Studies, Department of Geophysics, Colorado School
Effective Levi-Civita Dilaton theory from Metric Affine Dilaton Gravity
R. Scipioni
1999-05-25
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.
The JPL lunar gravity field to spherical harmonic degree 660 from the GRAIL Primary Mission
Konopliv, Alex S.
The lunar gravity field and topography provide a way to probe the interior structure of the Moon. Prior to the Gravity Recovery and Interior Laboratory (GRAIL) mission, knowledge of the lunar gravity was limited mostly to ...
Massive gravity on de Sitter and unique candidate for partially massless gravity
Rham, Claudia de; Renaux-Petel, Sébastien E-mail: srenaux@lpthe.jussieu.fr
2013-01-01
We derive the decoupling limit of Massive Gravity on de Sitter in an arbitrary number of space-time dimensions d. By embedding d-dimensional de Sitter into d+1-dimensional Minkowski, we extract the physical helicity-1 and helicity-0 polarizations of the graviton. The resulting decoupling theory is similar to that obtained around Minkowski. We take great care at exploring the partially massless limit and define the unique fully non-linear candidate theory that is free of the helicity-0 mode in the decoupling limit, and which therefore propagates only four degrees of freedom in four dimensions. In the latter situation, we show that a new Vainshtein mechanism is at work in the limit m{sup 2} ? 2H{sup 2} which decouples the helicity-0 mode when the parameters are different from that of partially massless gravity. As a result, there is no discontinuity between massive gravity and its partially massless limit, just in the same way as there is no discontinuity in the massless limit of massive gravity. The usual bounds on the graviton mass could therefore equivalently well be interpreted as bounds on m{sup 2}?2H{sup 2}. When dealing with the exact partially massless parameters, on the other hand, the symmetry at m{sup 2} = 2H{sup 2} imposes a specific constraint on matter. As a result the helicity-0 mode decouples without even the need of any Vainshtein mechanism.
Quantum Gravito-Optics: A Light Route from Semiclassical Gravity to Quantum Gravity
C. S. Unnikrishnan; George T. Gillies
2015-08-03
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.
Graceful Exit Inflation in $f(T)$ Gravity
G. G. L. Nashed; W. El Hanafy; Sh. Kh. Ibrahim
2015-04-04
We apply a quadratic teleparallel torsion scalar of the $f(T)=T+\\alpha T^{2}$ field equations to the spatially flat Friedmann-Robertson-Walker (FRW) model. We assume two perfect fluid components, the matter component has a fixed equation of state (EoS) parameter $\\omega$, while the torsion component has a dynamical EoS. We obtain an effective scale factor allowing a graceful exit inflation model with no need to slow roll technique. We perform a standard cosmological study to examine the cosmic evolution. In addition, the effective EoS shows consistent results confirming a smooth phase transition from inflation to radiation dominant universe. We consider the case when the torsion is made of a scalar field. This treatment enables us to induce a scalar field sensitive to the spacetime symmetry with an effective potential constructed from the quadratic $f(T)$ gravity. The model is parameterized by two parameters ($\\alpha,\\omega$) both derive the universe to exit out of de Sitter expansion. The first is purely gravitational and works effectively at large Hubble regime of the early stage allowing a slow roll potential. The second parameter $\\omega$ is a thermal-like correction coupled to the kinetic term and works effectively at low Hubble regime of late stages. The slow roll analysis of the obtained potential can perform tensor-to-scalar ratio and spectral index parameters consistent with the recent Planck and BICEP2 data. Both cosmological and scalar field analyses show consistent results.
Perturbations of nested branes with induced gravity
Sbisŕ, Fulvio; Koyama, Kazuya E-mail: kazuya.koyama@port.ac.uk
2014-06-01
We study the behaviour of weak gravitational fields in models where a 4D brane is embedded inside a 5D brane equipped with induced gravity, which in turn is embedded in a 6D spacetime. We consider a specific regularization of the branes internal structures where the 5D brane can be considered thin with respect to the 4D one. We find exact solutions corresponding to pure tension source configurations on the thick 4D brane, and study perturbations at first order around these background solutions. To perform the perturbative analysis, we adopt a bulk-based approach and we express the equations in terms of gauge invariant and master variables using a 4D scalar-vector-tensor decomposition. We then propose an ansatz on the behaviour of the perturbation fields when the thickness of the 4D brane goes to zero, which corresponds to configurations where gravity remains finite everywhere in the thin limit of the 4D brane. We study the equations of motion using this ansatz, and show that they give rise to a consistent set of differential equations in the thin limit, from which the details of the internal structure of the 4D brane disappear. We conclude that the thin limit of the ''ribbon'' 4D brane inside the (already thin) 5D brane is well defined (at least when considering first order perturbations around pure tension configurations), and that the gravitational field on the 4D brane remains finite in the thin limit. We comment on the crucial role of the induced gravity term on the 5D brane.
Testing chameleon gravity with the Coma cluster
Terukina, Ayumu; Yamamoto, Kazuhiro; Lombriser, Lucas; Bacon, David; Koyama, Kazuya; Nichol, Robert C. E-mail: lucas.lombriser@port.ac.uk E-mail: david.bacon@port.ac.uk E-mail: bob.nichol@port.ac.uk
2014-04-01
We propose a novel method to test the gravitational interactions in the outskirts of galaxy clusters. When gravity is modified, this is typically accompanied by the introduction of an additional scalar degree of freedom, which mediates an attractive fifth force. The presence of an extra gravitational coupling, however, is tightly constrained by local measurements. In chameleon modifications of gravity, local tests can be evaded by employing a screening mechanism that suppresses the fifth force in dense environments. While the chameleon field may be screened in the interior of the cluster, its outer region can still be affected by the extra force, introducing a deviation between the hydrostatic and lensing mass of the cluster. Thus, the chameleon modification can be tested by combining the gas and lensing measurements of the cluster. We demonstrate the operability of our method with the Coma cluster, for which both a lensing measurement and gas observations from the X-ray surface brightness, the X-ray temperature, and the Sunyaev-Zel'dovich effect are available. Using the joint observational data set, we perform a Markov chain Monte Carlo analysis of the parameter space describing the different profiles in both the Newtonian and chameleon scenarios. We report competitive constraints on the chameleon field amplitude and its coupling strength to matter. In the case of f(R) gravity, corresponding to a specific choice of the coupling, we find an upper bound on the background field amplitude of |f{sub R0}| < 6 × 10{sup ?5}, which is currently the tightest constraint on cosmological scales.
Gravity duals for non-relativistic CFTs
Koushik Balasubramanian; John McGreevy
2008-08-01
We attempt to generalize the AdS/CFT correspondence to non-relativistic conformal field theories which are invariant under Galilean transformations. Such systems govern ultracold atoms at unitarity, nucleon scattering in some channels, and more generally, a family of universality classes of quantum critical behavior. We construct a family of metrics which realize these symmetries as isometries. They are solutions of gravity with negative cosmological constant coupled to pressureless dust. We discuss realizations of the dust, which include a bulk superconductor. We develop the holographic dictionary and compute some two-point correlators. A strange aspect of the correspondence is that the bulk geometry has two extra noncompact dimensions.
A new quasidilaton theory of massive gravity
Mukohyama, Shinji
2014-12-01
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.
A high frequency resonance gravity gradiometer
Bagaev, S. N.; Kvashnin, N. L.; Skvortsov, M. N.; Bezrukov, L. B.; Krysanov, V. A.; Oreshkin, S. I.; Motylev, A. M.; Popov, S. M.; Samoilenko, A. A.; Yudin, I. S.; Rudenko, V. N.
2014-06-15
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.
Loop Quantum Gravity: An Inside View
Thomas Thiemann
2006-08-29
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.
Confronting Dilaton-exchange gravity with experiments
H. V. Klapdor-Kleingrothaus; H. Päs; U. Sarkar
2000-08-16
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.
Static wormholes in vacuum for conformal gravity
Julio Oliva; David Tempo; Ricardo Troncoso
2009-07-07
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.
Gamma Ray Burst Neutrinos Probing Quantum Gravity
M. C. Gonzalez-Garcia; F. Halzen
2006-11-28
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.
Linearization of Moffat's Symmetric Complex Metric Gravity
Joakim Munkhammar
2009-09-19
In this paper we investigate a complex symmetric generalization of general relativity and in particular we investigate its linearized field equations. We begin by reviewing some basic definitions and structures in Moffat's symmetric complex metric field theory of gravity. We then move on to derive the linearized retarded complex field equations. In addition to this we also derive a linearization of Moffat's field equations based on the more rigorous Fermi coordinate approach. In conclusion it is shown that the linearized symmetric complex field equations leads to a complex form of gravitomagnetism. We also briefly review the gravitational wave equation from the source less linearized symmetric complex field equations and discuss some open problems.
Gravity can be neither classical nor quantized
Sabine Hossenfelder
2012-12-03
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.
Null Energy Condition violations in bimetric gravity
Baccetti, Valentina; Visser, Matt
2012-01-01
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.
An overview of airborne radioactive emissions at Los Alamos National Laboratory
Guevara, F.A.; Dvorak, R.F.
1987-01-01
Strict control is essential over any emissions of radioactivity in the ventilation exhaust from facilities where radioactive materials may become airborne. At Los Alamos National Laboratory there are 87 stacks exhausting ventilation air to the environment from operations with a potential for radioactive emissions. These stacks cover the diverse operations at all Laboratory facilities where radioactive materials are handled and require continuous sampling/monitoring to detect levels of contamination. An overview is presented of the operations, associated ventilation exhaust cleanup systems, and analysis of the emissions. In keeping with the as-low-as-reasonably-achievable concept, emissions of radionuclides are reduced whenever practicable. A specific example describing the reduction of emissions from the linear accelerator beam stop area at the Los Alamos Meson Physics Facility during 1985 by a factor of 8 over previous emissions is presented.
Quality Assurance Project Plan for radioactive airborne emissions data compilation and reporting
Burris, S.A.; Thomas, S.P.
1994-02-01
This Quality Assurance Project Plan addresses the quality assurance requirements for compiling data from radioactie aiborne emissions. These data will be reported to the US Environmental Protection Agency, the US Department of Energy, and the Washington State Department of Health. Hanford Site radioactive airborne emissions are reported to the US Environmental Protection Agency in compliance with Title 40, Protection of the Environment, Code of Federal Regulations, Part 61, ``National Emissions Standards for Hazardous Air Pollutants , ``Subpart H, ``National Emissions Standards for Emissions of Radionuclides Other Than Radon From Department of Energy Facilities`` (EPA 1989a). Reporting to US Department of Energy is performed in compliance with requirements of US Department of Energy Order 5400.1, General Environmental Protection Program (DOE 1988a).
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
2015-05-01
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.
Stochastic cosmology, theories of perturbations and Lifshitz gravity
Khalatnikov, I M
2015-01-01
We review some works of E M Lifshitz connected with gravity and cosmology and also some later works, connected with his ideas. The main topics of this review are the stochastic cosmology of an anisotropic universe and of an isotropic universe with the scalar field, the quasi-isotropic (gradient) expansion in cosmology and Horava-Lifshitz gravity and cosmology.
Gravity Dual for Cyclic Renormalization Group Flow without Conformal Invariance
Yu Nakayama
2011-07-21
We construct a gravity dual for scale invariant but non-conformal field theories with a cyclic renormalization group flow. A slight modification of our construction gives a gravity dual of discretely scale invariant field theories. The underlying gravitational theory breaks the null energy condition.
Disformal transformations, veiled General Relativity and Mimetic Gravity
Deruelle, Nathalie; Rua, Josephine E-mail: rua@cbpf.br
2014-09-01
In this Note we show that Einstein's equations for gravity are generically invariant under ''disformations''. We also show that the particular subclass when this is not true yields the equations of motion of ''Mimetic Gravity''. Finally we give the ''mimetic'' generalization of the Schwarzschild solution.
Bimetric gravity doubly coupled to matter: theory and cosmological implications
Akrami, Yashar; Koivisto, Tomi S.; Mota, David F.; Sandstad, Marit E-mail: t.s.koivisto@astro.uio.no E-mail: marit.sandstad@astro.uio.no
2013-10-01
A ghost-free theory of gravity with two dynamical metrics both coupled to matter is shown to be consistent and viable. Its cosmological implications are studied, and the models, in particular in the context of partially massless gravity, are found to explain the cosmic acceleration without resorting to dark energy.
Ph.D.Thesis Binary inversion of gravity
Ph.D.Thesis Binary inversion of gravity data for salt imaging Richard A. Krahenbuhl Center of Mines Golden, CO 80401 http://www.geophysics.mines.edu/cgem CGEM #12;#12;Ph.D.Thesis Binary inversion) #12;#12;BINARY INVERSION OF GRAVITY DATA FOR SALT IMAGING by Richard A. Krahenbuhl #12;#12;ii A thesis
Simulation of Gravity Flow of Granular Materials in Silos
and handle vast quantities of raw materials in granular form. The material is usually retrieved throughSimulation of Gravity Flow of Granular Materials in Silos Pierre A. Gremaud1 and John V. Matthews1 materials in silos under the action of gravity is considered. In the case of a Mohr-Coulomb material
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
Gravity waves excited by jets: Propagation versus generation R. Plougonven
Plougonven, Riwal
Gravity waves excited by jets: Propagation versus generation R. Plougonven School of Mathematics imposed by the generation mechanism. In proceeding so, effects due to the propagation of the waves through in consequence that the gravity waves are generated in the jet-exit region. [4] To date, such arguments have
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
The Gravity of Annual Freight and Logistics Symposium
Minnesota, University of
The Gravity of Logistics 17th Annual Freight and Logistics Symposium A Summary Report | December 6 to those who want them --the "gravity" of logistics--depends on infrastructure that can support and sustainth Annual State of Logistics Report--IsThis the New Normal? Rosalyn Wilson, Senior Business Analyst
Multimodal standing gravity waves: a completely resonant system.
Iooss, Gérard
Multimodal standing gravity waves: a completely resonant system. G´erard Iooss , Pavel Plotnikov@hydro.nsc.ru Abstract The standing gravity wave problem on an infinitely deep fluid layer is considered under the form be expanded in powers of amplitude is then given up to order 2 . Key words: nonlinear water waves, standing
THE 2011 JUNE 23 STELLAR OCCULTATION BY PLUTO: AIRBORNE AND GROUND OBSERVATIONS
Person, M. J.; Bosh, A. S.; Levine, S. E.; Gulbis, A. A. S.; Zangari, A. M.; Zuluaga, C. A.; Sallum, S. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139-4307 (United States); Dunham, E. W.; Collins, P.; Bida, T.; Bright, L. [Lowell Observatory, Flagstaff, AZ (United States); Pasachoff, J. M.; Babcock, B. A.; Pandey, S.; Amrhein, D. [Williams College-Hopkins Observatory, Williamstown, MA (United States); Tholen, D. J. [Institute for Astronomy, University of Hawaii, Manoa, HI (United States); Taylor, B. [Boston University, Boston, MA (United States); Wolf, J.; Pfueller, E. [Deutsches SOFIA Institut, Universitaet Stuttgart, Pfaffenwaldring 29, D-70569 Stuttgart (Germany); Meyer, A., E-mail: mjperson@mit.edu [SOFIA Science Center, NASA Ames Research Center, MS 211-1, Moffett Field, CA 94035 (United States); and others
2013-10-01
On 2011 June 23, stellar occultations by both Pluto (this work) and Charon (future analysis) were observed from numerous ground stations as well as the Stratospheric Observatory for Infrared Astronomy (SOFIA). This first airborne occultation observation since 1995 with the Kuiper Airborne Observatory resulted in the best occultation chords recorded for the event, in three visible wavelength bands. The data obtained from SOFIA are combined with chords obtained from the ground at the IRTF, the U.S. Naval Observatory Flagstaff Station, and Leeward Community College to give the detailed state of the Pluto-Charon system at the time of the event with a focus on Pluto's atmosphere. The data show a return to the distinct upper and lower atmospheric regions with a knee or kink in the light curve separating them as was observed in 1988, rather than the smoothly transitioning bowl-shaped light curves of recent years. The upper atmosphere is analyzed by fitting a model to all of the light curves, resulting in a half-light radius of 1288 {+-} 1 km. The lower atmosphere is analyzed using two different methods to provide results under the differing assumptions of particulate haze and a strong thermal gradient as causes for the lower atmospheric diminution of flux. These results are compared with those from past occultations to provide a picture of Pluto's evolving atmosphere. Regardless of which lower atmospheric structure is assumed, results indicate that this part of the atmosphere evolves on short timescales with results changing the light curve structures between 1988 and 2006, and then reverting these changes in 2011 though at significantly higher pressures. Throughout these changes, the upper atmosphere remains remarkably stable in structure, again except for the overall pressure changes. No evidence of onset of atmospheric collapse predicted by frost migration models is seen, and the atmosphere appears to be remaining at a stable pressure level, suggesting it should persist at this full level through New Horizon's flyby in 2015.
Geophex Airborne Unmanned Survey System (GAUSS). Topical report, October 1993--September 1996
1998-12-31
This document is a Final Technical Report that describes the results of the Geophex Airborne Unmanned Survey System (GAUSS) research project. The objectives were to construct a geophysical data acquisition system that uses a remotely operated unmanned aerial vehicle (UAV) and to evaluate its effectiveness for characterization of hazardous environmental sites. The GAUSS is a data acquisition system that mitigates the potential risk to personnel during geophysical characterization of hazardous or radioactive sites. The fundamental basis of the GAUSS is as follows: (1) an unmanned survey vehicle carries geophysical sensors into a hazardous location, (2) the pilot remains outside the hazardous site and operates the vehicle using radio control, (3) geophysical measurements and their spatial locations are processed by an automated data-acquisition system which displays data on an off-site monitor in real-time, and (4) the pilot uses the display to direct the survey vehicle for complete site coverage. The objective of our Phase I research was to develop a data acquisition and processing (DAP) subsystem and geophysical sensors suitable for UAV deployment. We integrated these two subsystems to produce an automated, hand-held geophysical surveying system. The objective of the Phase II effort was to modify the subsystems and integrate them into an airborne prototype. The completed GAUSS DAP system consists of a UAV platform, a laser tracking and ranging subsystem, a telemetry subsystem, light-weight geophysical sensors, a base-station computer (BC), and custom-written survey control software (SCS). We have utilized off-the-shelf commercial products, where possible, to reduce cost and design time.
Harko, Tiberiu; Lobo, Francisco S.N.; Otalora, G.; Saridakis, Emmanuel N. E-mail: flobo@cii.fc.ul.pt
2014-12-01
We present an extension of f(T) gravity, allowing for a general coupling of the torsion scalar T with the trace of the matter energy-momentum tensor T. The resulting f(T,T) theory is a new modified gravity, since it is different from all the existing torsion or curvature based constructions. Applied to a cosmological framework, it leads to interesting phenomenology. In particular, one can obtain a unified description of the initial inflationary phase, the subsequent non-accelerating, matter-dominated expansion, and then the transition to a late-time accelerating phase. Additionally, the effective dark energy sector can be quintessence or phantom-like, or exhibit the phantom-divide crossing during the evolution. Moreover, in the far future the universe results either to a de Sitter exponential expansion, or to eternal power-law accelerated expansions. Finally, a detailed study of the scalar perturbations at the linear level reveals that f(T,T) cosmology can be free of ghosts and instabilities for a wide class of ansatzes and model parameters.
Vacuum energy: quantum hydrodynamics vs quantum gravity
G. E. Volovik
2005-09-09
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.
Quantum Foam, Gravity and Gravitational Waves
Cahill, R T
2003-01-01
The new information-theoretic Process Physics has shown that space is a quantum foam system with gravity being, in effect, an inhomogeneous in-flow of the quantum foam into matter. The theory predicts that absolute motion with respect to this system should be observable, and it is shown here that absolute motion has been detected in at least seven experiments. As well this experimental data also reveals the existence of a gravitational wave phenomena associated with the in-flow. It is shown that Galilean Relativity and Special Relativity are in fact compatible, contrary to current beliefs: absolute motion actually causes the special relativity effects. The new theory of gravity passes all the tests of the previous Newtonian and General Relativity theories, but in addition resolves the numerous gravitational anomalies such as the spiral galaxy `dark matter' effect, the absence of `dark matter' in elliptical galaxies, the inconsistencies in measuring G, the borehole g anomaly, and others. It is shown that Newto...
Motion in alternative theories of gravity
Gilles Esposito-Farese
2009-05-15
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.
Scattering amplitudes in super-renormalizable gravity
Pietro Donŕ; Stefano Giaccari; Leonardo Modesto; Leslaw Rachwal; Yiwei Zhu
2015-06-15
We explicitly compute the tree-level on-shell four-graviton amplitudes in four, five and six dimensions for local and weakly nonlocal gravitational theories that are quadratic in both, the Ricci and scalar curvature with form factors of the d'Alembertian operator inserted between. More specifically we are interested in renormalizable, super-renormalizable or finite theories. The scattering amplitudes for these theories turn out to be the same as the ones of Einstein gravity regardless of the explicit form of the form factors. As a special case the four-graviton scattering amplitudes in Weyl conformal gravity are identically zero. Using a field redefinition, we prove that the outcome is correct for any number of external gravitons (on-shell $n-$point functions) and in any dimension for a large class of theories. However, when an operator quadratic in the Riemann tensor is added in any dimension (with the exception of the Gauss-Bonnet term in four dimensions) the result is completely altered, and the scattering amplitudes depend on all the form factors introduced in the action.
Scattering amplitudes in super-renormalizable gravity
Donŕ, Pietro; Modesto, Leonardo; Rachwal, Leslaw; Zhu, Yiwei
2015-01-01
We explicitly compute the tree-level on-shell four-graviton amplitudes in four, five and six dimensions for local and weakly nonlocal gravitational theories that are quadratic in both, the Ricci and scalar curvature with form factors of the d'Alembertian operator inserted between. More specifically we are interested in renormalizable, super-renormalizable or finite theories. The scattering amplitudes for these theories turn out to be the same as the ones of Einstein gravity regardless of the explicit form of the form factors. As a special case the four-graviton scattering amplitudes in Weyl conformal gravity are identically zero. Using a field redefinition, we prove that the outcome is correct for any number of external gravitons (on-shell $n-$point functions) and in any dimension for a large class of theories. However, when an operator quadratic in the Riemann tensor is added in any dimension (with the exception of the Gauss-Bonnet term in four dimensions) the result is completely altered, and the scattering...
New ground state for quantum gravity
Joao Magueijo; Laura Bethke
2012-07-03
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.
Capozziello, S; Salzano, V
2008-01-01
It is nowadays accepted that the universe is undergoing a phase of accelerated expansion as tested by the Hubble diagram of Type Ia Supernovae (SNeIa) and several LSS observations. Future SNeIa surveys and other probes will make it possible to better characterize the dynamical state of the universe renewing the interest in cosmography which allows a model independent analysis of the distance - redshift relation. On the other hand, fourth order theories of gravity, also referred to as $f(R)$ gravity, have attracted a lot of interest since they could be able to explain the accelerated expansion without any dark energy. We show here how it is possible to relate the cosmographic parameters (namely the deceleration $q_0$, the jerk $j_0$, the snap $s_0$ and the lerk $l_0$ parameters) to the present day values of $f(R)$ and its derivatives $f^{(n)}(R) = d^nf/dR^n$ (with $n = 1, 2, 3$) thus offering a new tool to constrain such higher order models. Our analysis thus offers the possibility to relate the model independ...
S. Capozziello; V. F. Cardone; V. Salzano
2008-07-08
It is nowadays accepted that the universe is undergoing a phase of accelerated expansion as tested by the Hubble diagram of Type Ia Supernovae (SNeIa) and several LSS observations. Future SNeIa surveys and other probes will make it possible to better characterize the dynamical state of the universe renewing the interest in cosmography which allows a model independent analysis of the distance - redshift relation. On the other hand, fourth order theories of gravity, also referred to as $f(R)$ gravity, have attracted a lot of interest since they could be able to explain the accelerated expansion without any dark energy. We show here how it is possible to relate the cosmographic parameters (namely the deceleration $q_0$, the jerk $j_0$, the snap $s_0$ and the lerk $l_0$ parameters) to the present day values of $f(R)$ and its derivatives $f^{(n)}(R) = d^nf/dR^n$ (with $n = 1, 2, 3$) thus offering a new tool to constrain such higher order models. Our analysis thus offers the possibility to relate the model independent results coming from cosmography to the theoretically motivated assumptions of $f(R)$ cosmology.
Non-trivial 2+1-Dimensional Gravity
D. R. Grigore; G. Scharf
2010-08-07
We analyze 2+1-dimensional gravity in the framework of quantum gauge theory. We find that Einstein gravity has a trivial physical subspace which reflects the fact that the classical solution in empty space is flat. Therefore we study massive gravity which is not trivial. In the limit of vanishing graviton mass we obtain a non-trivial massless theory different from Einstein gravity. We derive the interaction from descent equations and obtain the cosmological topologically massive gravity. However, in addition to Einstein and Chern-Simons coupling we need coupling to fermionic ghost and anti-ghost fields and to a vector-graviton field with the same mass as the graviton.
Massive gravitational waves in Chern-Simons modified gravity
Myung, Yun Soo; Moon, Taeyoon E-mail: tymoon@inje.ac.kr
2014-10-01
We consider the nondynamical Chern-Simons (nCS) modified gravity, which is regarded as a parity-odd theory of massive gravity in four dimensions. We first find polarization modes of gravitational waves for ?=x/? in nCS modified gravity by using the Newman-Penrose formalism where the null complex tetrad is necessary to specify gravitational waves. We show that in the Newman–Penrose formalism, the number of polarization modes is one in addition to an unspecified ?{sub 4}, implying three degrees of freedom for ?=x/?. This compares with two for a canonical embedding of ?=t/?. Also, if one introduces the Ricci tensor formalism to describe a massive graviton arising from the nCS modified gravity, one finds one massive mode after making second-order wave equations, which is compared to five found from the parity-even Einstein–Weyl gravity.
Scalars, Vectors and Tensors from Metric-Affine Gravity
Karahan, Canan N; Demir, Durmus A
2011-01-01
The metric-affine gravity provides a useful framework for analyzing gravitational dynamics since it treats metric tensor and affine connection as fundamentally independent variables. In this work, we show that, a metric-affine gravity theory composed of the invariants formed from non-metricity, torsion and curvature tensors decomposes exhaustively into a theory of scalar, vector and tensor fields. These fields are natural candidates for the ones needed by various cosmological phenomena. Indeed, we show that the model accommodates TeVeS gravity (relativistic modified gravity theory), vector inflation, and aether-like models. Detailed analyses of these and other phenomena can lead to a standard metric-affine gravity model encoding scalars, vectors and tensors necessitated by cosmology.
Scalars, Vectors and Tensors from Metric-Affine Gravity
Canan N. Karahan; Asli Altas; Durmus A. Demir
2013-02-02
The metric-affine gravity provides a useful framework for analyzing gravitational dynamics since it treats metric tensor and affine connection as fundamentally independent variables. In this work, we show that, a metric-affine gravity theory composed of the invariants formed from non-metricity, torsion and curvature tensors can be decomposed into a theory of scalar, vector and tensor fields. These fields are natural candidates for the ones needed by various cosmological and other phenomena. Indeed, we show that the model accommodates TeVeS gravity (relativistic modified gravity theory), vector inflation, and aether-like models. Detailed analyses of these and other phenomena can lead to a standard metric-affine gravity model encoding scalars, vectors and tensors.
FAST CARS Developing a Laser Spectroscopic Technique for Rapid Identification of Bacterial Spores
Scully, M O; Lucht, R P; Opatrny, T; Pilloff, H; Rebane, A; Sokolov, A V; Zubairy, M S
2002-01-01
Airborne contaminants, e.g., bacterial spores, are usually analyzed by time consuming microscopic, chemical and biological assays. Current research into real time laser spectroscopic detectors of such contaminants is based on e.g. resonant Raman spectroscopy. The present approach derives from recent experiments in which atoms and molecules are prepared by one (or more) coherent laser(s) and probed by another set of lasers. The connection with previous studies based on "Coherent Anti-Stokes Raman Spectroscopy" (CARS) is to be noted. However generating and utilizing maximally coherent oscillation in macromolecules having an enormous number of degrees of freedom is much more challenging. This extension of the CARS technique is called FAST CARS (Femtosecond Adaptive Spectroscopic Techniques for Coherent Anti-Stokes Raman Spectroscopy), and the present paper proposes and analyses ways in which it could be used to rapidly identify pre-selected molecules in real time.
Query Optimization Techniques Class Hierarchies
Mannheim, Universität
Query Optimization Techniques Exploiting Class Hierarchies Sophie Cluet 1 Guido Moerkotte 2 1 INRIA Since the introduction of object base management systems (OBMS), many query optimization techniques tailored for object query languages have been proposed. They adapt known optimization techniques
Heal, Mathew R; Elton, Robert A; Hibbs, Leon R; Agius, Raymond M; Beverland, Iain J
2009-01-01
Objectives: To assess whether adverse acute cardiopulmonary health outcomes are associated with concentration of trace metals in airborne particulate matter. Methods: Daily PM10 and PM2.5 was collected for one year in ...
Werkheiser, Edwin Brooks, II
2006-10-30
This thesis seeks to identify, describe, and analyze the tactics used by the 101st Airborne Division in the pacification of the Republic of Vietnam's Thua Thien province from 1968 to 1972. Despite the larger calamity of ...
Qiang, Li-E
2015-01-01
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
2015-02-16
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.
Jacobson, R. A.
2014-11-01
French et al. determined the orbits of the Uranian rings, the orientation of the pole of Uranus, and the gravity harmonics of Uranus from Earth-based and Voyager ring occultations. Jacobson et al. determined the orbits of the Uranian satellites and the masses of Uranus and its satellites from Earth-based astrometry and observations acquired with the Voyager 2 spacecraft; they used the gravity harmonics and pole from French et al. Jacobson and Rush reconstructed the Voyager 2 trajectory and redetermined the Uranian system gravity parameters, satellite orbits, and ring orbits in a combined analysis of the data used previously augmented with additional Earth-based astrometry. Here we report on an extension of that work that incorporates additional astrometry and ring occultations together with improved data processing techniques.
Holt, Grady Lynn
1974-01-01
A COMPARATIVE STUDY OF COLLECTION EFFICIENCIES USING O. RO AND 1. 2 MICROMETER PORE SIZE FILTERS IN EVALUATING AIRBORNE ASBESTOS DUST A Thesis by GRADY LYNN HOLT Submitted to the Graduate College of' Texas A&M University in partial... fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1974. Major Subject: Industrial Hygiene A COMPARATIVE . TUDY OF COLLECTION EFFICIENCIES USING O. BO AND 1. 2 MICROMETER PORE SIZE FILTERS IN EVALUATING AIRBORNE ASBESTOS DUST A...
A length operator for canonical quantum gravity
T. Thiemann
1996-06-29
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
2000-08-18
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.
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
2009-01-01
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}).
Revisiting perturbations in extended quasidilaton massive gravity
Lavinia Heisenberg
2015-04-16
In this work we study the theory of extended quasidilaton massive gravity together with the presence of matter fields. After discussing the homogeneous and isotropic fully dynamical background equations, which governs the exact expansion history of the universe, we consider small cosmological perturbations around these general FLRW solutions. The stability of tensor, vector and scalar perturbations on top of these general background solutions give rise to slightly different constraints on the parameters of the theory than those obtained in the approximative assumption of the late-time asymptotic form of the expansion history, which does not correspond to our current epoch. This opens up the possibility of stable FLRW solutions to be compared with current data on cosmic expansion with the restricted parameter space based on theoretical ground.
Revisiting perturbations in extended quasidilaton massive gravity
Heisenberg, Lavinia
2015-01-01
In this work we study the theory of extended quasidilaton massive gravity together with the presence of matter fields. After discussing the homogeneous and isotropic fully dynamical background equations, which governs the exact expansion history of the universe, we consider small cosmological perturbations around these general FLRW solutions. The stability of tensor, vector and scalar perturbations on top of these general background solutions give rise to slightly different constraints on the parameters of the theory than those obtained in the approximative assumption of the late-time asymptotic form of the expansion history, which does not correspond to our current epoch. This opens up the possibility of stable FLRW solutions to be compared with current data on cosmic expansion with the restricted parameter space based on theoretical ground.
Nonsingular cosmology from evolutionary quantum gravity
Francesco Cianfrani; Giovanni Montani; Fabrizio Pittorino
2014-10-30
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.
Black Hole Thermodynamics in Modified Gravity
Jonas R. Mureika; John W. Moffat; Mir Faizal
2015-03-03
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.
What is Dynamics in Quantum Gravity?
Malkiewicz, Przemyslaw
2015-01-01
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
2015-05-18
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
2009-01-01
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.
Solar system tests of Ho?ava-Lifshitz gravity
Tiberiu Harko; Zoltan Kovács; Francisco S. N. Lobo
2010-10-28
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.
Dandina N. Rao; Subhash C. Ayirala; Madhav M. Kulkarni; Wagirin Ruiz Paidin; Thaer N. N. Mahmoud; Daryl S. Sequeira; Amit P. Sharma
2006-09-30
This is the final report describing the evolution of the project ''Development and Optimization of Gas-Assisted Gravity Drainage (GAGD) Process for Improved Light Oil Recovery'' from its conceptual stage in 2002 to the field implementation of the developed technology in 2006. This comprehensive report includes all the experimental research, models developments, analyses of results, salient conclusions and the technology transfer efforts. As planned in the original proposal, the project has been conducted in three separate and concurrent tasks: Task 1 involved a physical model study of the new GAGD process, Task 2 was aimed at further developing the vanishing interfacial tension (VIT) technique for gas-oil miscibility determination, and Task 3 was directed at determining multiphase gas-oil drainage and displacement characteristics in reservoir rocks at realistic pressures and temperatures. The project started with the task of recruiting well-qualified graduate research assistants. After collecting and reviewing the literature on different aspects of the project such gas injection EOR, gravity drainage, miscibility characterization, and gas-oil displacement characteristics in porous media, research plans were developed for the experimental work to be conducted under each of the three tasks. Based on the literature review and dimensional analysis, preliminary criteria were developed for the design of the partially-scaled physical model. Additionally, the need for a separate transparent model for visual observation and verification of the displacement and drainage behavior under gas-assisted gravity drainage was identified. Various materials and methods (ceramic porous material, Stucco, Portland cement, sintered glass beads) were attempted in order to fabricate a satisfactory visual model. In addition to proving the effectiveness of the GAGD process (through measured oil recoveries in the range of 65 to 87% IOIP), the visual models demonstrated three possible multiphase mechanisms at work, namely, Darcy-type displacement until gas breakthrough, gravity drainage after breakthrough and film-drainage in gas-invaded zones throughout the duration of the process. The partially-scaled physical model was used in a series of experiments to study the effects of wettability, gas-oil miscibility, secondary versus tertiary mode gas injection, and the presence of fractures on GAGD oil recovery. In addition to yielding recoveries of up to 80% IOIP, even in the immiscible gas injection mode, the partially-scaled physical model confirmed the positive influence of fractures and oil-wet characteristics in enhancing oil recoveries over those measured in the homogeneous (unfractured) water-wet models. An interesting observation was that a single logarithmic relationship between the oil recovery and the gravity number was obeyed by the physical model, the high-pressure corefloods and the field data.
T. Jenke; G. Cronenberg; P. Geltenbort; A. N. Ivanov; T. Lauer; T. Lins; U. Schmidt; H. Saul; H. Abele
2012-08-19
The evidence for the observation of the Higgs spin-0-boson as a manifestation of a scalar field provides the missing corner stone for the standard model of particles (SM). However, the SM fails to explain the non-visible but gravitationally active part of the universe. Its nature is unknown but the confirmation of a scalar Higgs is giving a boost to scalar-field-theories. So far gravity experiments and observations performed at different distances find no deviation from Newton's gravity law. Therefore dark energy must possess a screening mechanism which suppresses the scalar-mediated fifth force. Our line of attack is a novel gravity experiment with neutrons based on a quantum interference technique. The spectroscopic measurement of quantum states on resonances with an external coupling makes this a powerful search for dark matter and dark energy contributions in the universe. Quantum states in the gravity potential are intimately related to other scalar field or spin-0-bosons if they exist. If the reason is that some undiscovered particle interact with a neutron, this results in a measurable energy shift of quantum states in the gravity potential, because for neutrons the screening effect is absent. We use Gravity Resonance Spectroscopy to measure the energy splitting at the highest level of precision, providing a constraint on any possible new interaction. We obtain a sensitivity of 10^-14 eV. We set an experimental limit on any fifth force, in particular on parameter \\beta<2x10^9 at n=3 for the scalar chameleon field, which is improved by a factor of 100 compared to our previous experiment and five orders of magnitude better than from precision tests of atomic spectra. The pseudoscalar axion coupling is constrained to gsgp/\\hbar c<3x10^-16 at 20\\mu m, which is an improvement by a factor of 30. These results indicate that gravity is understood at this improved level of precision.
Exoplanet Detection Techniques
Fischer, Debra A; Laughlin, Greg P; Macintosh, Bruce; Mahadevan, Suvrath; Sahlmann, Johannes; Yee, Jennifer C
2015-01-01
We are still in the early days of exoplanet discovery. Astronomers are beginning to model the atmospheres and interiors of exoplanets and have developed a deeper understanding of processes of planet formation and evolution. However, we have yet to map out the full complexity of multi-planet architectures or to detect Earth analogues around nearby stars. Reaching these ambitious goals will require further improvements in instrumentation and new analysis tools. In this chapter, we provide an overview of five observational techniques that are currently employed in the detection of exoplanets: optical and IR Doppler measurements, transit photometry, direct imaging, microlensing, and astrometry. We provide a basic description of how each of these techniques works and discuss forefront developments that will result in new discoveries. We also highlight the observational limitations and synergies of each method and their connections to future space missions.
Resin infiltration transfer technique
Miller, David V. (Pittsburgh, PA); Baranwal, Rita (Glenshaw, PA)
2009-12-08
A process has been developed for fabricating composite structures using either reaction forming or polymer infiltration and pyrolysis techniques to densify the composite matrix. The matrix and reinforcement materials of choice can include, but are not limited to, silicon carbide (SiC) and zirconium carbide (ZrC). The novel process can be used to fabricate complex, net-shape or near-net shape, high-quality ceramic composites with a crack-free matrix.
Fu, C.Y.; Petrich, L.I.
1997-03-25
An image is compressed by identifying edge pixels of the image; creating a filled edge array of pixels each of the pixels in the filled edge array which corresponds to an edge pixel having a value equal to the value of a pixel of the image array selected in response to the edge pixel, and each of the pixels in the filled edge array which does not correspond to an edge pixel having a value which is a weighted average of the values of surrounding pixels in the filled edge array which do correspond to edge pixels; and subtracting the filled edge array from the image array to create a difference array. The edge file and the difference array are then separately compressed and transmitted or stored. The original image is later reconstructed by creating a preliminary array in response to the received edge file, and adding the preliminary array to the received difference array. Filling is accomplished by solving Laplace`s equation using a multi-grid technique. Contour and difference file coding techniques also are described. The techniques can be used in a method for processing a plurality of images by selecting a respective compression approach for each image, compressing each of the images according to the compression approach selected, and transmitting each of the images as compressed, in correspondence with an indication of the approach selected for the image. 16 figs.
Fu, Chi-Yung (San Francisco, CA); Petrich, Loren I. (Livermore, CA)
1997-01-01
An image is compressed by identifying edge pixels of the image; creating a filled edge array of pixels each of the pixels in the filled edge array which corresponds to an edge pixel having a value equal to the value of a pixel of the image array selected in response to the edge pixel, and each of the pixels in the filled edge array which does not correspond to an edge pixel having a value which is a weighted average of the values of surrounding pixels in the filled edge array which do correspond to edge pixels; and subtracting the filled edge array from the image array to create a difference array. The edge file and the difference array are then separately compressed and transmitted or stored. The original image is later reconstructed by creating a preliminary array in response to the received edge file, and adding the preliminary array to the received difference array. Filling is accomplished by solving Laplace's equation using a multi-grid technique. Contour and difference file coding techniques also are described. The techniques can be used in a method for processing a plurality of images by selecting a respective compression approach for each image, compressing each of the images according to the compression approach selected, and transmitting each of the images as compressed, in correspondence with an indication of the approach selected for the image.
S. MacMullin; G. K. Giovanetti; M. P. Green; R. Henning; R. Holmes; K. Vorren; J. F. Wilkerson
2012-10-03
We present measurements of airborne fission products in Chapel Hill, NC, USA, from 62 days following the March 11, 2011, accident at the Fukushima Dai-ichi nuclear power plant. Airborne particle samples were collected daily in air filters and radio-assayed with two high-purity germanium (HPGe) detectors. The fission products I-131 and Cs-137 were measured with maximum activities of 4.2 +/- 0.6 mBq/m^3 and 0.42 +/- 0.07 mBq/m^3 respectively. Additional activity from I-131, I-132, Cs-134, Cs-136, Cs-137 and Te-132 were measured in the same air filters using a low-background HPGe detector at the Kimballton Underground Research Facility (KURF).
DL Edwards; KD Shields; MJ Sula; MY Ballinger
1999-09-28
Assessments were performed to evaluate compliance with the airborne radionuclide emission monitoring requirements in the National Emission Standards for Hazardous Air Pollutants (NESHAP--US Code of Federal Regulations, Title 40 Part 61, Subpart H). In these assessments, potential unabated offsite doses were evaluated for emission locations at facilities owned by the US Department of Energy and operated by Pacific Northwest National Laboratory (Pacific Northwest) on the Hanford Site. Two of the facilities evaluated, 325 Building Radiochemical Processing Laboratory, and 331 Building Life Sciences Laboratory met state and federal criteria for continuous sampling of airborne radionuclide emissions. One other building, the 3720 Environmental Sciences Laboratory, was recognized as being in transition with the potential for meeting the continuous sampling criteria.
PHYSICS OF FLUIDS 25, 086604 (2013) Gravity currents shoaling on a slope
Sutherland, Bruce
2013-01-01
water rivers into the saline ocean form surface gravity currents. The study of gravity currents is also spills in the ocean.6 Gravity currents in a channel have been well studied through lockPHYSICS OF FLUIDS 25, 086604 (2013) Gravity currents shoaling on a slope Bruce R. Sutherland,1,2,a
Gravity observations and 3D structure of the Earth , F. Chambat
1 Gravity observations and 3D structure of the Earth Y. Ricard1 , F. Chambat Laboratoire des, Michigan-Ann Harbor University, USA. Short title: GRAVITY OBSERVATIONS AND 3D STRUCTURE OF THE EARTH 1. The determination of Earth's gravity field has benefited from various gravity missions that have been launched
Gravity inversion using a binary formulation Richard A. Krahenbuhl* and Yaoguo Li
Gravity inversion using a binary formulation Richard A. Krahenbuhl* and Yaoguo Li Gravity contrast that gives rise to zero gravity response on the surface. As a result, part of the salt structure structure using gravity data can be divided into two general categories. The first are interface inversions
GRAVITY PERTURBED CRAPPER WAVES BENJAMIN F. AKERS, DAVID M. AMBROSE & J. DOUGLAS WRIGHT
Wright, J. Douglas
GRAVITY PERTURBED CRAPPER WAVES BENJAMIN F. AKERS, DAVID M. AMBROSE & J. DOUGLAS WRIGHT Abstract for but gravity is neglected. For certain parameter values, Crapper waves are known to have multi-valued height by the effect of gravity, yielding the existence of gravity-capillary waves nearby to the Crapper waves
Emergent gravity/Non-linear U(1) gauge theory correspondence
Supriya Kar; K. Priyabrat Pandey; Abhishek K. Singh; Sunita Singh
2010-02-21
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.
Particles on a Circle in Canonical Lineal Gravity
R. B. Mann
2001-05-02
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.
Flat space (higher spin) gravity with chemical potentials
Michael Gary; Daniel Grumiller; Max Riegler; Jan Rosseel
2014-11-24
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.
Jinsong Yang; Yongge Ma
2015-06-11
To adopt a practical method to calculate the action of geometrical operators on quantum states is a crucial task in loop quantum gravity. In the series of papers, we will introduce a graphical method, developed by Yutsis and Brink, to loop quantum gravity. The graphical method provides a very powerful technique for simplifying complicated calculations. In this first paper, the closed formula of volume operator is derived via the graphical method. By employing suitable and non-ambiguous graphs to represent the acting of operators as well as the spin network states, we use the simple rules for transforming graphs to yield the resulting formula. Comparing with the complicated algebraic derivation in some literatures, our procedure is more concise, intuitive and visual. The resulting matrix elements of volume operator is compact and uniform, fitting for both gauge-invariant and gauge-variant spin network states.
Chen, DI-WEN
2001-11-21
Airborne hazardous plumes inadvertently released during nuclear/chemical/biological incidents are mostly of unknown composition and concentration until measurements are taken of post-accident ground concentrations from plume-ground deposition of constituents. Unfortunately, measurements often are days post-incident and rely on hazardous manned air-vehicle measurements. Before this happens, computational plume migration models are the only source of information on the plume characteristics, constituents, concentrations, directions of travel, ground deposition, etc. A mobile ''lighter than air'' (LTA) system is being developed at Oak Ridge National Laboratory that will be part of the first response in emergency conditions. These interactive and remote unmanned air vehicles will carry light-weight detectors and weather instrumentation to measure the conditions during and after plume release. This requires a cooperative computationally organized, GPS-controlled set of LTA's that self-coordinate around the objectives in an emergency situation in restricted time frames. A critical step before an optimum and cost-effective field sampling and monitoring program proceeds is the collection of data that provides statistically significant information, collected in a reliable and expeditious manner. Efficient aerial arrangements of the detectors taking the data (for active airborne release conditions) are necessary for plume identification, computational 3-dimensional reconstruction, and source distribution functions. This report describes the application of stochastic or geostatistical simulations to delineate the plume for guiding subsequent sampling and monitoring designs. A case study is presented of building digital plume images, based on existing ''hard'' experimental data and ''soft'' preliminary transport modeling results of Prairie Grass Trials Site. Markov Bayes Simulation, a coupled Bayesian/geostatistical methodology, quantitatively combines soft information regarding contaminant location with hard experimental results. Soft information is used to build an initial conceptual image of where contamination is likely to be. As experimental data are collected and analyzed, indicator kriging is used to update the initial conceptual image. The sequential Gaussian simulation is then practiced to make a comparison between the two simulations. Simulated annealing is served as a postprocessor to improve the result of Markov Bayes simulation or sequential Gaussian simulation.
M Corriveau; H Jamieson; M Parsons; J Campbell; A Lanzirotti
2011-12-31
Windblown and vehicle-raised dust from unvegetated mine tailings can be a human health risk. Airborne particles from As-rich abandoned Au mine tailings from Nova Scotia, Canada have been characterized in terms of particle size, As concentration, As oxidation state, mineral species and texture. Samples were collected in seven aerodynamically fractionated size ranges (0.5-16 {micro}m) using a cascade impactor deployed at three tailings fields. All three sites are used for recreational activities and off-road vehicles were racing on the tailings at two mines during sample collection. Total concentrations of As in the <8 {micro}m fraction varied from 65 to 1040 ng/m{sup 3} of air as measured by proton-induced X-ray emission (PIXE) analysis. The same samples were analysed by synchrotron-based microfocused X-ray absorption near-edge spectroscopy ({micro}XANES) and X-ray diffraction ({micro}XRD) and found to contain multiple As-bearing mineral species, including Fe-As weathering products. The As species present in the dust were similar to those observed in the near-surface tailings. The action of vehicles on the tailings surface may disaggregate material cemented with Fe arsenate and contribute additional fine-grained As-rich particles to airborne dust. Results from this study can be used to help assess the potential human health risks associated with exposure to airborne particles from mine tailings.
Turbulent round jet under gravity waves
Ryu, Yong Uk
2002-01-01
The behavior of a neutrally buoyant horizontal turbulent round jet under a wavy environment was investigated. Progressive waves with different wave amplitudes in an intermediate water depth were used. The Particle Image Velocimetry (PIV) technique...
Waggoner, L.O.
1998-02-05
The presentation focuses on some of the time-proven and new technologies being used to accomplish radiological work. These techniques can be applied at nuclear facilities to reduce radiation doses and protect the environment. The last reactor plants and processing facilities were shutdown and Hanford was given a new mission to put the facilities in a safe condition, decontaminate, and prepare them for decommissioning. The skills that were necessary to operate these facilities were different than the skills needed today to clean up Hanford. Workers were not familiar with many of the tools, equipment, and materials needed to accomplish:the new mission, which includes clean up of contaminated areas in and around all the facilities, recovery of reactor fuel from spent fuel pools, and the removal of millions of gallons of highly radioactive waste from 177 underground tanks. In addition, this work has to be done with a reduced number of workers and a smaller budget. At Hanford, facilities contain a myriad of radioactive isotopes that are 2048 located inside plant systems, underground tanks, and the soil. As cleanup work at Hanford began, it became obvious early that in order to get workers to apply ALARA and use hew tools and equipment to accomplish the radiological work it was necessary to plan the work in advance and get radiological control and/or ALARA committee personnel involved early in the planning process. Emphasis was placed on applying,ALARA techniques to reduce dose, limit contamination spread and minimize the amount of radioactive waste generated. Progress on the cleanup has,b6en steady and Hanford workers have learned to use different types of engineered controls and ALARA techniques to perform radiological work. The purpose of this presentation is to share the lessons learned on how Hanford is accomplishing radiological work.
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory of raregovAboutRecovery ActTools to someone byApplied Science/Techniques
Asymptotically anti-de Sitter spacetimes in topologically massive gravity
Marc Henneaux; Cristian Martinez; Ricardo Troncoso
2009-03-31
We consider asymptotically anti-de Sitter spacetimes in three-dimensional topologically massive gravity with a negative cosmological constant, for all values of the mass parameter $\\mu$ ($\\mu\
TOPOLOGICAL GRAVITY IN GENUS 2 WITH TWO PRIMARY FIELDS
TOPOLOGICAL GRAVITY IN GENUS 2 WITH TWO PRIMARY FIELDS TOHRU EGUCHI, EZRA GETZLER AND CHUAN TOHRU EGUCHI, EZRA GETZLER AND CHUAN-SHENG XIONG 1.2. The topological recursion relation in genus 0
Application Of Gravity And Deep Dipole Geoelectrics In The Volcanic...
Application Of Gravity And Deep Dipole Geoelectrics In The Volcanic Area Of Mt Etna (Sicily) Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article:...
Three-dimensional gravity and deformations of relativistic symmetries
Trzesniewski, T
2015-01-01
It is possible that relativistic symmetries become deformed in the semiclassical regime of quantum gravity. Mathematically, such deformations lead to the noncommutativity of spacetime geometry and non-vanishing curvature of momentum space. The best studied example is given by the $\\kappa$-Poincar\\'e Hopf algebra, associated with $\\kappa$-Minkowski space. On the other hand, the curved momentum space is a well-known feature of particles coupled to three-dimensional gravity. The purpose of this thesis was to explore some properties and mutual relations of the above two models. In particular, I study extensively the spectral dimension of $\\kappa$-Minkowski space. I also present an alternative limit of the Chern-Simons theory describing three-dimensional gravity with particles. Then I discuss the spaces of momenta corresponding to conical defects in higher dimensional spacetimes. Finally, I consider the Fock space construction for the quantum theory of particles in three-dimensional gravity.
Gravity wave turbulence revealed by horizontal vibrations of the container
Bruno Issenmann; Eric Falcon
2012-12-20
We experimentally study the role of the forcing on gravity-capillary wave turbulence. Previous laboratory experiments using spatially localized forcing (vibrating blades) have shown that the frequency power-law exponent of the gravity wave spectrum depends on the forcing parameters. By horizontally vibrating the whole container, we observe a spectrum exponent that does not depend on the forcing parameters for both gravity and capillary regimes. This spatially extended forcing leads to a gravity spectrum exponent in better agreement with the theory than by using a spatially localized forcing. The role of the vessel shape has been also studied. Finally, the wave spectrum is found to scale linearly with the injected power for both regimes whatever the forcing type used.
Mixed convection and heat management in the Mars gravity biosatellite
Marsh, Jesse B. (Jesse Benjamin)
2007-01-01
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 ...
Regional Gravity Survey of the Northern Great Salt Lake Desert...
Regional Gravity Survey of the Northern Great Salt Lake Desert and Adjacent Areas in Utah, Nevada, and Idaho Jump to: navigation, search OpenEI Reference LibraryAdd to library...
The Basics of Water Waves Theory for Analogue Gravity
Germain Rousseaux
2012-03-14
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.
Light deflection in Weyl gravity: critical distances for photon paths
S. Pireaux
2004-03-16
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.
Acoustic-Gravity Waves Interacting with a Rectangular Trench
Kadri, Usama
2015-01-01
A mathematical solution of the two-dimensional linear problem of an acoustic-gravity wave interacting with a rectangular trench, in a compressible ocean, is presented. Expressions for the flow field on both sides of the ...
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.
2015-07-30
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
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...
Sudarshan Ananth; Mahendra Mali
2015-04-11
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.
An alternative derivation of the Minimal massive 3D gravity
Ahmet Baykal
2014-12-23
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.
Ground Gravity Survey At Mt Princeton Hot Springs Geothermal...
lithologic distrubtions Notes Gravity low associated with Mt. Princeton Batholith; density contrast of -0.5 gcm3 of valley-fill sediments relative to batholith References J.E....
Gravity Effects on Antimatter in the Standard-Model Extension
Jay D. Tasson
2015-01-30
The gravitational Standard-Model Extension (SME) is the general field-theory based framework for the analysis of CPT and Lorentz violation. In this work we summarize the implications of Lorentz and CPT violation for antimatter gravity in the context of the SME. Implications of various attempts to place indirect limits on anomalous antimatter gravity are considered in the context of SME-based models.
Extended disformal approach in the scenario of Rainbow Gravity
Carvalho, Gabriel G; Bittencourt, Eduardo
2015-01-01
We investigate all feasible mathematical representations of disformal transformations on a space-time metric according to the action of a linear operator upon the manifold's tangent and cotangent bundles. The geometric, algebraic and group structures of this operator and their interfaces are analyzed in detail. Then, we scrutinize a possible physical application, providing a new covariant formalism for a phenomenological approach to quantum gravity known as Rainbow Gravity.
Gravity-free hydraulic jumps and metal femtocups
Rama Govindarajan; Manikandan Mathur; Ratul DasGupta; N. R. Selvi; Neena Susan John; G. U. Kulkarni
2006-10-03
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.
Probing strongly coupled anisotropic plasmas from higher curvature gravity
Viktor Jahnke; Anderson Seigo Misobuchi
2015-10-23
We consider five-dimensional AdS-axion-dilaton gravity with a Gauss-Bonnet term and use a black brane solution displaying spatial anisotropy as the gravity dual of a strongly coupled anisotropic plasma. We compute several observables relevant to the study of the plasma, namely, the drag force, the jet quenching parameter, the quarkonium potential and the thermal photon production. The effects of higher derivative corrections and of the anisotropy are discussed and compared with previous results.
Entropy and Area of Black Holes in Loop Quantum Gravity
I. B. Khriplovich
2002-03-31
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.
On the Hamiltonian form of 3D massive gravity
Olaf Hohm; Alasdair Routh; Paul K. Townsend; Baocheng Zhang
2012-09-14
We present a "Chern-Simons-like" action for the "general massive gravity" model propagating two spin-2 modes with independent masses in three spacetime dimensions (3D), and we use it to find a simple Hamiltonian form of this model. The number of local degrees of freedom, determined by the dimension of the physical phase space, agrees with a linearized analysis except in some limits, in particular that yielding "new topologically massive gravity", which therefore suffers from a linearization instability.
Gravity interpretation of the northern Overthrust Belt, Idaho and Wyoming
Silver, Wendy Ilene
1979-01-01
GRAVITY INTERPRETATION OF THE NORTHERN OVERTHRUST BELT, IDAHO AND 'vlYOMING A Thesis by IJENDY ILENE SILVER Submitted to the Graduate College of Texas ARM University in partial fulfillment of the requirements for the deoree of MASTER... OF SCIFNCE December 1979 Major Subject: Geology GRAVITY INTERPRETATION OF THE NORTHERN OVERTHRUST lIELT, . IDAHO AND NYOMING A Thesis by NENDY ILEI'lE 5!, LVER Approved as to style and content by: (Chairman of Committee (Hea o epartment (i~1embe...
A Hopf Algebra Structure in Self-dual Gravity
Hugo Garcia-Compean; Laura E. Morales; Jerzy F. Plebanski
1996-01-20
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.
Zaromb, Solomon
2004-07-13
Air is sampled at a rate in excess of 100 L/min, preferably at 200-300 L/min, so as to collect therefrom a substantial fraction, i.e., at least 20%, preferably 60-100%, of airborne particulates. A substance of interest (analyte), such as lead, is rapidly solubilized from the the collected particulates into a sample of liquid extractant, and the concentration of the analyte in the extractant sample is determined. The high-rate air sampling and particulate collection may be effected with a high-throughput filter cartridge or with a recently developed portable high-throughput liquid-absorption air sampler. Rapid solubilization of lead is achieved by a liquid extractant comprising 0.1-1 M of acetic acid or acetate, preferably at a pH of 5 or less and preferably with inclusion of 1-10% of hydrogen peroxide. Rapid determination of the lead content in the liquid extractant may be effected with a colorimetric or an electroanalytical analyzer.
Kristofzski, J.G.; Alison, D.
1992-04-01
The information provided in this document meets the quality assurance (QA) requirements for the National Emission Standards for Hazardous Air Pollutants'' (NESHAP) (EPA 1989a) radionuclide airborne emissions control program in accordance with the regulation's referenced stack monitoring method (i.e. Method 114) for the Plutonium Finishing Plant (PFP). At the Hanford Site, the operations personnel have primary responsibility for implementing the continuous radionuclide emission measurements in conformance with NESHAP. Continuous measurement is used to describe continuous sampling of the effluent stream withdrawn and subjected to radiochemical analysis, and monitoring of radionuclide particulate emissions for administrative control. This Quality Assurance Project Plan (QAPjP) fully describes these PFP- implemented activities and the associated QA program as required by the NESHAP. The information is provided in the format specified in QAMS/005, Interim Guidelines and Specifications for Preparing Quality Assurance Project Plans (EPA 1983a). This QAPjP describes the QA program for only those activities that are the responsibility of the PFP: operation, calibration, and maintenance of the sampling systems. The QA requirements for laboratory services, data compilation, and data reporting are beyond the scope of this QAPjP.
Kristofzski, J.G.; Alison, D.
1992-04-01
The information provided in this document meets the quality assurance (QA) requirements for the ``National Emission Standards for Hazardous Air Pollutants`` (NESHAP) (EPA 1989a) radionuclide airborne emissions control program in accordance with the regulation`s referenced stack monitoring method (i.e. Method 114) for the Plutonium Finishing Plant (PFP). At the Hanford Site, the operations personnel have primary responsibility for implementing the continuous radionuclide emission measurements in conformance with NESHAP. Continuous measurement is used to describe continuous sampling of the effluent stream withdrawn and subjected to radiochemical analysis, and monitoring of radionuclide particulate emissions for administrative control. This Quality Assurance Project Plan (QAPjP) fully describes these PFP- implemented activities and the associated QA program as required by the NESHAP. The information is provided in the format specified in QAMS/005, Interim Guidelines and Specifications for Preparing Quality Assurance Project Plans (EPA 1983a). This QAPjP describes the QA program for only those activities that are the responsibility of the PFP: operation, calibration, and maintenance of the sampling systems. The QA requirements for laboratory services, data compilation, and data reporting are beyond the scope of this QAPjP.
Perihelion precession for modified Newtonian gravity
Schmidt, Hans-Juergen
2008-07-15
We calculate the perihelion precession {delta} for nearly circular orbits in a central potential V(r). Differently from other approaches to this problem, we do not assume that the potential is close to the Newtonian one. The main idea in the deduction is to apply the underlying symmetries of the system to show that {delta} must be a function of r{center_dot}V{sup ''}(r)/V{sup '}(r) and to use the transformation behavior of {delta} in a rotating system of reference. This is equivalent to say that the effective potential can be written in a one-parameter set of possibilities as the sum of centrifugal potential and potential of the central force. We get the following universal formula valid for V{sup '}(r)>0 reading {delta}(r)=2{pi}{center_dot}[(1/{radical}(3+r{center_dot}V{sup ''}(r)/V{sup '}(r)))-1]. It has to be read as follows: a circular orbit at this value r exists and is stable if and only if this {delta} is well-defined as real; and if this is the case, then the angular difference from one perihelion to the next one for nearly circular orbits at this r is exactly 2{pi}+{delta}(r). Then we apply this result to examples of recent interest like modified Newtonian gravity and linearized fourth-order gravity. In the second part of the paper, we generalize this universal formula to static spherically symmetric space-times ds{sup 2}=-e{sup 2{lambda}}{sup (r)}dt{sup 2}+e{sup 2{mu}}{sup (r)}dr{sup 2}+r{sup 2}d{omega}{sup 2}; for orbits near r it reads {delta}=2{pi}{center_dot}[(e{sup {mu}}{sup (r)}/{radical}(3-2r{center_dot}{lambda}{sup '}(r)+r{center_dot}{lambda}{sup ''}(r)/{lambda}{sup '}(r)))-1] and can be applied to a large class of theories. For the Schwarzschild black hole with mass parameter m>0 it leads to {delta}=2{pi}{center_dot}[(1/{radical}(1-(6m/r)))-1], a surprisingly unknown formula. It represents a strict result and is applicable for all values r>6m and is in good agreement with the fact that stable circular orbits exist for r>6m only. For r>>m, one can develop in powers of m and get the well-known approximation {delta}{approx_equal}(6{pi}m/r)
Cosmological stability bound in massive gravity and bigravity
Fasiello, Matteo; Tolley, Andrew J. E-mail: andrew.j.tolley@case.edu
2013-12-01
We give a simple derivation of a cosmological bound on the graviton mass for spatially flat FRW solutions in massive gravity with an FRW reference metric and for bigravity theories. This bound comes from the requirement that the kinetic term of the helicity zero mode of the graviton is positive definite. The bound is dependent only on the parameters in the massive gravity potential and the Hubble expansion rate for the two metrics. We derive the decoupling limit of bigravity and FRW massive gravity, and use this to give an independent derivation of the cosmological bound. We recover our previous results that the tension between satisfying the Friedmann equation and the cosmological bound is sufficient to rule out all observationally relevant FRW solutions for massive gravity with an FRW reference metric. In contrast, in bigravity this tension is resolved due to different nature of the Vainshtein mechanism. We find that in bigravity theories there exists an FRW solution with late-time self-acceleration for which the kinetic terms for the helicity-2, helicity-1 and helicity-0 are generically nonzero and positive making this a compelling candidate for a model of cosmic acceleration. We confirm that the generalized bound is saturated for the candidate partially massless (bi)gravity theories but the existence of helicity-1/helicity-0 interactions implies the absence of the conjectured partially massless symmetry for both massive gravity and bigravity.
Finite field-dependent symmetries in perturbative quantum gravity
Upadhyay, Sudhaker
2014-01-15
In this paper we discuss the absolutely anticommuting nilpotent symmetries for perturbative quantum gravity in general curved spacetime in linear and non-linear gauges. Further, we analyze the finite field-dependent BRST (FFBRST) transformation for perturbative quantum gravity in general curved spacetime. The FFBRST transformation changes the gauge-fixing and ghost parts of the perturbative quantum gravity within functional integration. However, the operation of such symmetry transformation on the generating functional of perturbative quantum gravity does not affect the theory on physical ground. The FFBRST transformation with appropriate choices of finite BRST parameter connects non-linear Curci–Ferrari and Landau gauges of perturbative quantum gravity. The validity of the results is also established at quantum level using Batalin–Vilkovisky (BV) formulation. -- Highlights: •The perturbative quantum gravity is treated as gauge theory. •BRST and anti-BRST transformations are developed in linear and non-linear gauges. •BRST transformation is generalized by making it finite and field dependent. •Connection between linear and non-linear gauges is established. •Using BV formulation the results are established at quantum level also.
The covariant formulation of $f(T)$ gravity
Krššák, Martin
2015-01-01
We show that the well-known problem of frame dependence and violation of local Lorentz invariance in the usual formulation of $f(T)$ gravity is a consequence of neglecting the role of spin connection. We re-formulate $f(T)$ gravity starting, instead of the "pure-tetrad" teleparallel gravity, from the covariant teleparallel gravity, using both the tetrad and the spin connection as dynamical variables, resulting in the fully covariant, consistent, and frame-independent, version of $f(T)$ gravity, which does not suffer from the notorious problems of the usual, pure-tetrad, $f(T)$ theory. We present the method to extract solutions for the most physically important cases, such as the Minkowski, the FRW and the spherically-symmetric ones. We show that in the covariant $f(T)$ gravity we are allowed to use an arbitrary tetrad in an arbitrary coordinate system along with the corresponding spin connection, resulting always to the same physically relevant field equations.
TESTING ALTERNATIVE THEORIES OF GRAVITY USING THE SUN
Casanellas, Jordi; Pani, Paolo; Lopes, Ilidio; Cardoso, Vitor E-mail: paolo.pani@ist.utl.pt E-mail: vitor.cardoso@ist.utl.pt
2012-01-20
We propose a new approach to test possible corrections to Newtonian gravity using solar physics. The high accuracy of current solar models and new precise observations allow us to constrain corrections to standard gravity at unprecedented levels. Our case study is Eddington-inspired gravity, an attractive modified theory of gravity which results in non-singular cosmology and collapse. The theory is equivalent to standard gravity in vacuum, but it sensibly differs from it within matter. For instance, it affects the evolution and the equilibrium structure of the Sun, giving different core temperature profiles, and deviations in the observed acoustic modes and in solar neutrino fluxes. Comparing the predictions from a modified solar model with observations, we constrain the coupling parameter of the theory, |{kappa}{sub g}| {approx}< 3 Multiplication-Sign 10{sup 5} m{sup 5} s{sup -2} kg{sup -1}. Our results show that the Sun can be used to efficiently constrain alternative theories of gravity.
2011-01-01
Summertime ambient formaldehyde in five U.S. metropolitanin Redistributing Formaldehyde to the Upper Troposphere Overoxidation in airborne formaldehyde measurements during
Post-Newtonian, Quasi-Circular Binary Inspirals in Quadratic Modified Gravity
Kent Yagi; Leo C. Stein; Nicolas Yunes; Takahiro Tanaka
2012-04-16
We consider a general class of quantum gravity-inspired, modified gravity theories, where the Einstein-Hilbert action is extended through the addition of all terms quadratic in the curvature tensor coupled to scalar fields with standard kinetic energy. This class of theories includes Einstein-Dilaton-Gauss-Bonnet and Chern-Simons modified gravity as special cases. We analytically derive and solve the coupled field equations in the post-Newtonian approximation, assuming a comparable-mass, spinning black hole binary source in a quasi-circular, weak-field/slow-motion orbit. We find that a naive subtraction of divergent piece associated with the point-particle approximation is ill-suited to represent compact objects in these theories. Instead, we model them by appropriate effective sources built so that known strong-field solutions are reproduced in the far-field limit. In doing so, we prove that black holes in Einstein-Dilaton-Gauss-Bonnet and Chern-Simons theory can have hair, while neutron stars have no scalar monopole charge, in diametrical opposition to results in scalar-tensor theories. We then employ techniques similar to the direct integration of the relaxed Einstein equations to obtain analytic expressions for the scalar field, metric perturbation, and the associated gravitational wave luminosity measured at infinity. We find that scalar field emission mainly dominates the energy flux budget, sourcing electric-type (even-parity) dipole scalar radiation and magnetic-type (odd-parity) quadrupole scalar radiation, correcting the General Relativistic prediction at relative -1PN and 2PN orders. Such modifications lead to corrections in the emitted gravitational waves that can be mapped to the parameterized post-Einsteinian framework. Such modifications could be strongly constrained with gravitational wave observations.