Mielke, E W
2006-01-01
Anomalies in Yang-Mills type gauge theories of gravity are reviewed. Particular attention is paid to the relation between the Dirac spin, the axial current j_5 and the non-covariant gauge spin C. Using diagrammatic techniques, we show that only generalizations of the U(1)- Pontrjagin four--form F^ F= dC arise in the chiral anomaly, even when coupled to gravity. Implications for Ashtekar's canonical approach to quantum gravity are discussed.
Interior Alaska Bouguer Gravity Anomaly
National Oceanic and Atmospheric Administration, Department of Commerce — A 1 kilometer Complete Bouguer Anomaly gravity grid of interior Alaska. Only those grid cells within 10 kilometers of a gravity data point have gravity values....
Interior Alaska Bouguer Gravity Anomaly
National Oceanic and Atmospheric Administration, Department of Commerce — A 1 kilometer Complete Bouguer Anomaly gravity grid of interior Alaska. All grid cells within the rectangular data area (from 61 to 66 degrees North latitude and...
SEG US Bouguer Gravity Anomaly Grid
National Oceanic and Atmospheric Administration, Department of Commerce — The SEG gravity data are the product of the ad hoc Gravity Anomaly Map (GAM) Committee, sponsored by the Society of Exploration Geophysicists (SEG) and the U.S....
S. G. Pugacheva
2015-01-01
Full Text Available The source of gravity anomalies of the Moon are large mascons with a high mass concentration at a depth of volcanic plains and lunar Maria. New data on the gravitational field of the Moon were obtained from two Grail spacecrafts. The article presents the data of physical and mechanical properties of the surface soil layer of the lunar Maria and gives an assessment of the chemical composition of the soil. There have been calculated heterogeneity parameters of the surface macro-relief of the lunar Maria: albedo, soil density, average grain diameter of the particles forming the surface layer and the volume fraction occupied by particles. It can be assumed that mascons include rich KREEP rocks with a high content of thorium and iron oxide. Formation of mascons is connected with intensive development of basaltic volcanism on the Moon in the early periods of its existence.
Isostatic residual gravity anomaly data grid for the conterminous US
U.S. Geological Survey, Department of the Interior — The grid of isostatic residual gravity anomaly data was produced from the grid of Bouguer gravity anomaly data (see Bouguer gravity metadata) by using an...
Consistent anomalies of the induced W gravities
Abud, M; Cappiello, L
1995-01-01
The BRST anomaly which may be present in the induced W_n gravity quantized on the light-cone is evaluated in the geometrical framework of Zucchini. The cocycles linked by the cohomology of the BRST operator to the anomaly are straightforwardly calculated thanks to the analogy between this formulation and the Yang-Mills theory. We give also a conformally covariant formulation of these quantities including the anomaly, which is valid on arbitrary Riemann surfaces. The example of the W_3 theory is discussed and a comparison with other candidates for the anomaly available in the literature is presented.
Geologic Interpretation of Gravity Anomalies
1990-04-19
the density of the crystalline rocks virtually depends only on their chemical -mineralogical composition and structural special features. 0 DOC...point out that deep analog of gabbro (a-2.9 - 3.1 g/cm3) is eclogite, in essence not differing from it by chemical composition, but which is...qrivity interpretation. Geophys.. vol. X XV, No 3, I II0. If is g hs e s D. The analitic bas’ic of gravity interpirrtation. Geophys., J sin g K
Conformal Anomaly and Counterterms in Designer Gravity
Anabalon, Andres; Choque, David; Martinez, Cristian
2015-01-01
We construct concrete counterterms of the Balasubramanian-Kraus type for Einstein-scalar theories with designer gravity boundary conditions in AdS$_{4}$, so that the total action is finite on-shell and satisfy a well defined variational principle for an arbitrary scalar field potential. We focus on scalar fields with the conformal mass, $m^{2}=-2l^{-2}$, and show that the holographic mass matches the Hamiltonian mass for any boundary conditions. We compute the conformal anomaly of the dual field theory in the generic case, as well as when there exist logarithmic branches of non-linear origin. As expected, the conformal anomaly vanishes for the boundary conditions that are AdS invariant. When the anomaly does not vanish, the dual stress tensor describes a thermal gas with an equation of state related to the boundary conditions of the scalar field. When the anomaly vanishes, we recover the dual theory of a massless thermal gas. As an application of the formalism, we consider a general family of exact hairy blac...
Bouguer gravity anomaly data grid for the conterminous US
U.S. Geological Survey, Department of the Interior — The grid of gravity anomaly data for the conterminous United States and adjacent marine areas was constructed from National Information Mapping Agency (NIMA) gravity...
Gravity and geothermal anomalies in Borno Basin, Nigeria ...
PROMOTING ACCESS TO AFRICAN RESEARCH ... This paper briefly attempts the interpretation of the gravity anomalies to ... gravity data to geodynamics in the exploration for geothermal energy as an additional source of energy for Nigeria.
Axial gravity, massless fermions and trace anomalies
Bonora, L.; Cvitan, M.; Prester, P. Dominis; Pereira, A. Duarte; Giaccari, S.; Štemberga, T.
2017-08-01
This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones.
Forward Modeling of Gravity, Gravity Gradients,and Magnetic Anomalies due to Complex Bodies
Luo Yao; Yao Changli
2007-01-01
On the basis of the results of improved analytical expression of computation of gravity anomalies due to a homogeneous polyhedral body composed of polygonal facets, and applying the forward theory with the coordinate transformation of vectors and tensors, we deduced both the analytical expressions for gravity gradient tensors and for magnetic anomalies of a polygon, and obtained new analytical expressions for computing vertical gradients of gravity anomalies and vertical component of magnetic anomalies caused by a polyhedral body. And also we developed explicitly the complete unified expressions for the calculation of gravity anomalies, gravity gradient, and magnetic anomalies due to the homogeneous polyhedron. Furthermore, we deduced new analytical expressions for computing vertical gradients of gravity anomalies due to a finite rectangular prism by applying the newly obtained expressions for gravity gradient tensors due to a polyhedral target body. Comparison with forward calculation of models shows the correctness of these new expressions. It will reduce forward calculation time of gravity-magnetic anomalies and improve computational efficiency by applying our unified expressions for joint forward modeling of gravity-magnetic anomalies due to homogeneous polyhedral bodies.
Bouguer gravity anomaly data grid for the conterminous US
U.S. Geological Survey, Department of the Interior — The grid of gravity anomaly data for the conterminous United States and adjacent marine areas was constructed from National Information Mapping Agency (NIMA)...
Bouguer Gravity Anomaly Map of Bangladesh (grav8bg)
U.S. Geological Survey, Department of the Interior — This coverage includes arcs and arc labels that hold the Bouguer Gravity anomaly value for contours and type contours of the original map of Bangladesh with the same...
Quantum gravity momentum representation and maximum energy
Moffat, J. W.
2016-11-01
We use the idea of the symmetry between the spacetime coordinates xμ and the energy-momentum pμ in quantum theory to construct a momentum space quantum gravity geometry with a metric sμν and a curvature tensor Pλ μνρ. For a closed maximally symmetric momentum space with a constant 3-curvature, the volume of the p-space admits a cutoff with an invariant maximum momentum a. A Wheeler-DeWitt-type wave equation is obtained in the momentum space representation. The vacuum energy density and the self-energy of a charged particle are shown to be finite, and modifications of the electromagnetic radiation density and the entropy density of a system of particles occur for high frequencies.
Maine Offshore Free-air Anomaly Gravity
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (5,363 records) were compiled by the U. S. Geological Survey. This data base was received on February 23, 1993. Principal gravity parameters...
Maine Onshore Complete Bouguer Gravity Anomaly Data
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (18,461 records) were compiled by the U. S. Geological Survey. This data base was received on February 23, 1993. Principal gravity...
Detailed gravity anomalies from GEOS-3 satellite altimetry data
Gopalapillai, G. S.; Mourad, A. G.
1978-01-01
A technique for deriving mean gravity anomalies from dense altimetry data was developed. A combination of both deterministic and statistical techniques was used. The basic mathematical model was based on the Stokes' equation which describes the analytical relationship between mean gravity anomalies and geoid undulations at a point; this undulation is a linear function of the altimetry data at that point. The overdetermined problem resulting from the excessive altimetry data available was solved using Least-Squares principles. These principles enable the simultaneous estimation of the associated standard deviations reflecting the internal consistency based on the accuracy estimates provided for the altimetry data as well as for the terrestrial anomaly data. Several test computations were made of the anomalies and their accuracy estimates using GOES-3 data.
Fluid/Gravity Correspondence, Second Order Transport and Gravitational Anomaly
Megias, Eugenio
2013-01-01
We study the transport properties of a relativistic fluid affected by chiral and gauge-gravitational anomalies. The computation is performed in the framework of the fluid/gravity correspondence for a 5 dim holographic model with Chern-Simons terms in the action. We find new anomalous and non anomalous transport coefficients, as well as new contributions to the existing ones coming from the mixed gauge-gravitational anomaly. Consequences for the shear waves dispersion relation are analyzed.
Refining geoid and vertical gradient of gravity anomaly
Zhang Chijun
2011-11-01
Full Text Available We have derived and tested several relations between geoid (N and quasi-geoid (ζ with model validation. The elevation correction consists of the first-term (Bouguer anomaly and second-term (vertical gradient of gravity anomaly. The vertical gradient was obtained from direct measurement and terrain calculation. The test results demonstrated that the precision of geoid can reach centimeter-level in mountains less than 5000 meters high.
Transgressions and Holographic Conformal Anomalies for Chern-Simons Gravities
Mora, Pablo
2010-01-01
I present two calculations of the holographic Weyl anomalies induced by Chern-Simons gravity theories alternative to the ones presented in the literature. The calculations presented here rest on the extension from Chern-Simons to Transgression forms as lagrangians, motivated by gauge invariance, which automatically yields the boundary terms suitable to regularize the theory. The procedure followed here sheds light in the structure of Chern-Simons gravities and their regularization.
Gravity Anomaly Assessment Using Ggms and Airborne Gravity Data Towards Bathymetry Estimation
Tugi, A.; Din, A. H. M.; Omar, K. M.; Mardi, A. S.; Som, Z. A. M.; Omar, A. H.; Yahaya, N. A. Z.; Yazid, N.
2016-09-01
The Earth's potential information is important for exploration of the Earth's gravity field. The techniques of measuring the Earth's gravity using the terrestrial and ship borne technique are time consuming and have limitation on the vast area. With the space-based measuring technique, these limitations can be overcome. The satellite gravity missions such as Challenging Mini-satellite Payload (CHAMP), Gravity Recovery and Climate Experiment (GRACE), and Gravity-Field and Steady-State Ocean Circulation Explorer Mission (GOCE) has introduced a better way in providing the information on the Earth's gravity field. From these satellite gravity missions, the Global Geopotential Models (GGMs) has been produced from the spherical harmonics coefficient data type. The information of the gravity anomaly can be used to predict the bathymetry because the gravity anomaly and bathymetry have relationships between each other. There are many GGMs that have been published and each of the models gives a different value of the Earth's gravity field information. Therefore, this study is conducted to assess the most reliable GGM for the Malaysian Seas. This study covered the area of the marine area on the South China Sea at Sabah extent. Seven GGMs have been selected from the three satellite gravity missions. The gravity anomalies derived from the GGMs are compared with the airborne gravity anomaly, in order to figure out the correlation (R2) and the root mean square error (RMSE) of the data. From these assessments, the most suitable GGMs for the study area is GOCE model, GO_CONS_GCF_2_TIMR4 with the R2 and RMSE value of 0.7899 and 9.886 mGal, respectively. This selected model will be used in the estimating the bathymetry for Malaysian Seas in future.
GRAVITY ANOMALY ASSESSMENT USING GGMS AND AIRBORNE GRAVITY DATA TOWARDS BATHYMETRY ESTIMATION
A. Tugi
2016-09-01
Full Text Available The Earth’s potential information is important for exploration of the Earth’s gravity field. The techniques of measuring the Earth’s gravity using the terrestrial and ship borne technique are time consuming and have limitation on the vast area. With the space-based measuring technique, these limitations can be overcome. The satellite gravity missions such as Challenging Mini-satellite Payload (CHAMP, Gravity Recovery and Climate Experiment (GRACE, and Gravity-Field and Steady-State Ocean Circulation Explorer Mission (GOCE has introduced a better way in providing the information on the Earth’s gravity field. From these satellite gravity missions, the Global Geopotential Models (GGMs has been produced from the spherical harmonics coefficient data type. The information of the gravity anomaly can be used to predict the bathymetry because the gravity anomaly and bathymetry have relationships between each other. There are many GGMs that have been published and each of the models gives a different value of the Earth’s gravity field information. Therefore, this study is conducted to assess the most reliable GGM for the Malaysian Seas. This study covered the area of the marine area on the South China Sea at Sabah extent. Seven GGMs have been selected from the three satellite gravity missions. The gravity anomalies derived from the GGMs are compared with the airborne gravity anomaly, in order to figure out the correlation (R2 and the root mean square error (RMSE of the data. From these assessments, the most suitable GGMs for the study area is GOCE model, GO_CONS_GCF_2_TIMR4 with the R2 and RMSE value of 0.7899 and 9.886 mGal, respectively. This selected model will be used in the estimating the bathymetry for Malaysian Seas in future.
Bathymetry Prediction Based on the Admittance Theory of Gravity Anomalies
OUYANG Mingda
2015-10-01
Full Text Available Based on the admittance theory of gravity anomalies, the method of bathymetry prediction was studied in detail in this paper. In frequency domains, the correlation between gravity anomalies and bathymetry was analyzed, which suggests that the wavelength band correlated strongly was in a range of 20—300 km, this band was appropriated to inverse bathymetry by gravity anomalies. Took the Emperor Chain as an example, the uncompensated admittance model and flexural isostatic admittance model were used for researching, respectively, the included parameter of crust thickness and effective elastic thickness were calculated by the isostatic response function. As the down continuation factor was unstable, a high-cut filter was proposed in the inversion procedure to ensure convergence of series. The results showed that, the admittance theory of gravity anomalies can be used effectively in the bathymetry prediction, the predicted result was real and reliable, the relative precision was approximately 6%, which was equal to ETOPO1 model, and the detailed feature of sea floor which was not showed in ETOPO1 model can also be depicted; the precisions were not so well in areas of ocean mountains intensively distributed because of the complexion of the sea floor.
On the non-uniqueness of local quasi-geoids computed from terrestrial gravity anomalies
Prutkin, I.; Klees, R.
2007-01-01
We consider the problem of local (quasi-)geoid modelling from terrestrial gravity anomalies. Whereas this problem is uniquely solvable (up to spherical harmonic degree one) if gravity anomalies are globally available, the problem is non-unique if gravity anomalies are only available within a local a
On the non-uniqueness of local quasi-geoids computed from terrestrial gravity anomalies
Prutkin, I.; Klees, R.
2007-01-01
We consider the problem of local (quasi-)geoid modelling from terrestrial gravity anomalies. Whereas this problem is uniquely solvable (up to spherical harmonic degree one) if gravity anomalies are globally available, the problem is non-unique if gravity anomalies are only available within a local
Blaser, Nicole; Guskov, Sergei I; Entin, Vladimir A; Wolfer, David P; Kanevskyi, Valeryi A; Lipp, Hans-Peter
2014-11-15
The gravity vector theory postulates that birds determine their position to set a home course by comparing the memorized gravity vector at the home loft with the local gravity vector at the release site, and that they should adjust their flight course to the gravity anomalies encountered. As gravity anomalies are often intermingled with geomagnetic anomalies, we released experienced pigeons from the center of a strong circular gravity anomaly (25 km diameter) not associated with magnetic anomalies and from a geophysical control site, equidistant from the home loft (91 km). After crossing the border zone of the anomaly--expected to be most critical for pigeon navigation--they dispersed significantly more than control birds, except for those having met a gravity anomaly en route. These data increase the credibility of the gravity vector hypothesis. © 2014. Published by The Company of Biologists Ltd.
Hawking radiation from gravity's rainbow via gravitational anomaly
Zeng Xiao-Xiong; Yang Shu-Zheng; Chen De-You
2008-01-01
Based on the anomaly cancellation method,initiated by Robinson and Wilczek,we investigates Hawking radiation from the modified Schwarzschild black hole from gravity's rainbow from the anomaly point of view.Unlike the general Schwarzschild space-time,the metric of this black hole depends on the energies of probes.The obtained result shows to restore the underlying general covariance at the quantum level in the effective field,the covariant compensating flux of energy-momentum tensor,which is related to the energies of the probes,should precisely equal to that of a (1+1)-dimensional blackbody at the Hawking temperature.
Gravity anomaly during the Mohe total solar eclipse
无
2001-01-01
By using a high-precision LaCoste-Romberg (1)-122#) gravimeter, continuous and precise measurements were carried out during the March 9, 1997 total solar eclipse in the Mohe region in Northeast China. The gravity variations were digitally recorded during the total solar eclipse so as to investigate the possible anomaly of the sun and the moon's gravitational fields on the earth. After the careful processing and analysis of the observed data, no significant anomaly during the very solar eclipse has been found. Howmetrical decrease of about 6- 7 μGal at the first contact and the last contact. This is the anomaly phenomenon observed and reported for the first time in the literature. This note presents some analyses and discussions.
New analytic solutions for modeling vertical gravity gradient anomalies
Kim, Seung-Sep; Wessel, Paul
2016-05-01
Modern processing of satellite altimetry for use in marine gravimetry involves computing the along-track slopes of observed sea-surface heights, projecting them into east-west and north-south deflection of the vertical grids, and using Laplace's equation to algebraically obtain a grid of the vertical gravity gradient (VGG). The VGG grid is then integrated via overlapping, flat Earth Fourier transforms to yield a free-air anomaly grid. Because of this integration and associated edge effects, the VGG grid retains more short-wavelength information (e.g., fracture zone and seamount signatures) that is of particular importance for plate tectonic investigations. While modeling of gravity anomalies over arbitrary bodies has long been a standard undertaking, similar modeling of VGG anomalies over oceanic features is not commonplace yet. Here we derive analytic solutions for VGG anomalies over simple bodies and arbitrary 2-D and 3-D sources. We demonstrate their usability in determining mass excess and deficiency across the Mendocino fracture zone (a 2-D feature) and find the best bulk density estimate for Jasper seamount (a 3-D feature). The methodologies used herein are implemented in the Generic Mapping Tools, available from gmt.soest.hawaii.edu.
The interpretation of gravity anomaly on lunar Apennines
无
2009-01-01
The lunar Apennines,located in the southeast of Mare Imbrium,is the largest range on the Moon. The gravity anomalies on profiles across the mountains reveal evidence of a great fault zone characteristic. The deep crustal structures of lunar Apennines are analyzed on the basis of topographic data from Chang’E-1 satellite and gravity data from Lunar Prospector. The inverted crust-mantle models indicate the presence of a lithosphere fault beneath the mountains. Inverted results of gravity and the hypothe-sis of lunar thermal evolution suggest that the lunar lithosphere might be broken ～3.85 Ga ago due to a certain dynamic lateral movement and compression of lunar lithosphere. This event is associated with the history of magma filling and lithosphere deformation in the mountain zone and adjacent area. Moreover,the formation and evolution of Imbrium basin impose this effect on the process.
The interpretation of gravity anomaly on lunar Apennines
CHEN Chao; CHEN Bo; PING JinSong; LIANG Qing; HUANG Qian; ZHAO WenJin; ZHANG ChangDa
2009-01-01
The lunar Apennines, located in the southeast of Mare Imbrium, is the largest range on the Moon. The gravity anomalies on profiles across the mountains reveal evidence of a great fault zone characteristic.The deep crustal structures of lunar Apennines are analyzed on the basis of topographic data from Chang'E-1 satellite and gravity data from Lunar Prospector. The inverted crust-mantle models indicate the presence of a lithosphere fault beneath the mountains. Inverted results of gravity and the hypothesis of lunar thermal evolution suggest that the lunar lithosphere might be broken ～3.85 Ga ago due to a certain dynamic lateral movement and compression of lunar lithosphere. This event is associated with the history of magma filling and lithosphere deformation in the mountain zone and adjacent area. Moreover, the formation and evolution of Imbrium basin impose this effect on the process.
Gravity anomalies were developed in Fourier series in two test areas: 2 x 3 deg area in the State of Ohio, and 10 x 35 deg area in the Atlantic...based only on the original anomaly values and the topography, and the mean gravity anomalies were estimated for the same squares as in the Fourier series method...The result is that this second manual method has smaller standard errors than the Fourier series method, and that this kind of extrapolation
The quest for the perfect gravity anomaly: Part 2 - Mass effects and anomaly inversion
Keller, Gordon R.; Hildenbrand, T.G.; Hinze, W. J.; Li, X.; Ravat, D.; Webring, M.
2006-01-01
Gravity anomalies have become an important tool for geologic studies since the widespread use of high-precision gravimeters after the Second World War. More recently the development of instrumentation for airborne gravity observations, procedures for acquiring data from satellite platforms, the readily available Global Positioning System for precise vertical and horizontal control, improved global data bases, and enhancement of computational hardware and software have accelerated the use of the gravity method. As a result, efforts are being made to improve the gravity databases that are made available to the geoscience community by broadening their observational holdings and increasing the accuracy and precision of the included data. Currently the North American Gravity Database as well as the individual databases of Canada, Mexico, and the United States of America are being revised using new formats and standards. The objective of this paper is to describe the use of the revised standards for gravity data processing and modeling and there impact on geological interpretations. ?? 2005 Society of Exploration Geophysicists.
Altered orientation and flight paths of pigeons reared on gravity anomalies: a GPS tracking study.
Blaser, Nicole; Guskov, Sergei I; Meskenaite, Virginia; Kanevskyi, Valerii A; Lipp, Hans-Peter
2013-01-01
The mechanisms of pigeon homing are still not understood, in particular how they determine their position at unfamiliar locations. The "gravity vector" theory holds that pigeons memorize the gravity vector at their home loft and deduct home direction and distance from the angular difference between memorized and actual gravity vector. However, the gravity vector is tilted by different densities in the earth crust leading to gravity anomalies. We predicted that pigeons reared on different gravity anomalies would show different initial orientation and also show changes in their flight path when crossing a gravity anomaly. We reared one group of pigeons in a strong gravity anomaly with a north-to-south gravity gradient, and the other group of pigeons in a normal area but on a spot with a strong local anomaly with a west-to-east gravity gradient. After training over shorter distances, pigeons were released from a gravitationally and geomagnetically normal site 50 km north in the same direction for both home lofts. As expected by the theory, the two groups of pigeons showed divergent initial orientation. In addition, some of the GPS-tracked pigeons also showed changes in their flight paths when crossing gravity anomalies. We conclude that even small local gravity anomalies at the birth place of pigeons may have the potential to bias the map sense of pigeons, while reactivity to gravity gradients during flight was variable and appeared to depend on individual navigational strategies and frequency of position updates.
Altered orientation and flight paths of pigeons reared on gravity anomalies: a GPS tracking study.
Nicole Blaser
Full Text Available The mechanisms of pigeon homing are still not understood, in particular how they determine their position at unfamiliar locations. The "gravity vector" theory holds that pigeons memorize the gravity vector at their home loft and deduct home direction and distance from the angular difference between memorized and actual gravity vector. However, the gravity vector is tilted by different densities in the earth crust leading to gravity anomalies. We predicted that pigeons reared on different gravity anomalies would show different initial orientation and also show changes in their flight path when crossing a gravity anomaly. We reared one group of pigeons in a strong gravity anomaly with a north-to-south gravity gradient, and the other group of pigeons in a normal area but on a spot with a strong local anomaly with a west-to-east gravity gradient. After training over shorter distances, pigeons were released from a gravitationally and geomagnetically normal site 50 km north in the same direction for both home lofts. As expected by the theory, the two groups of pigeons showed divergent initial orientation. In addition, some of the GPS-tracked pigeons also showed changes in their flight paths when crossing gravity anomalies. We conclude that even small local gravity anomalies at the birth place of pigeons may have the potential to bias the map sense of pigeons, while reactivity to gravity gradients during flight was variable and appeared to depend on individual navigational strategies and frequency of position updates.
Optimal, scalable forward models for computing gravity anomalies
May, Dave A
2011-01-01
We describe three approaches for computing a gravity signal from a density anomaly. The first approach consists of the classical "summation" technique, whilst the remaining two methods solve the Poisson problem for the gravitational potential using either a Finite Element (FE) discretization employing a multilevel preconditioner, or a Green's function evaluated with the Fast Multipole Method (FMM). The methods utilizing the PDE formulation described here differ from previously published approaches used in gravity modeling in that they are optimal, implying that both the memory and computational time required scale linearly with respect to the number of unknowns in the potential field. Additionally, all of the implementations presented here are developed such that the computations can be performed in a massively parallel, distributed memory computing environment. Through numerical experiments, we compare the methods on the basis of their discretization error, CPU time and parallel scalability. We demonstrate t...
Optimization schemes for the inversion of Bouguer gravity anomalies
Zamora, Azucena
Data sets obtained from measurable physical properties of the Earth structure have helped advance the understanding of its tectonic and structural processes and constitute key elements for resource prospecting. 2-Dimensional (2-D) and 3-D models obtained from the inversion of geophysical data sets are widely used to represent the structural composition of the Earth based on physical properties such as density, seismic wave velocities, magnetic susceptibility, conductivity, and resistivity. The inversion of each one of these data sets provides structural models whose consistency depends on the data collection process, methodology, and overall assumptions made in their individual mathematical processes. Although sampling the same medium, seismic and non-seismic methods often provide inconsistent final structural models of the Earth with varying accuracy, sensitivity, and resolution. Taking two or more geophysical data sets with complementary characteristics (e.g. having higher resolution at different depths) and combining their individual strengths to create a new improved structural model can help achieve higher accuracy and resolution power with respect to its original components while reducing their ambiguity and uncertainty effects. Gravity surveying constitutes a cheap, non-invasive, and non-destructive passive remote sensing method that helps to delineate variations in the gravity field. These variations can originate from regional anomalies due to deep density variations or from residual anomalies related to shallow density variations [41]. Since gravity anomaly inversions suffer from significant non-uniqueness (allowing two or more distinct density structures to have the same gravity signature) and small changes in parameters can highly impact the resulting model, the inversion of gravity data represents an ill-posed mathematical problem. However, gravity studies have demonstrated the effectiveness of this method to trace shallow subsurface density variations
Fluid/Gravity Correspondence, Second Order Transport and Gravitational Anomaly***
Megías, Eugenio; Pena-Benitez, Francisco
2014-03-01
We study the transport properties of a relativistic fluid affected by chiral and gauge-gravitational anomalies. The computation is performed in the framework of the fluid/gravity correspondence for a 5 dim holographic model with Chern-Simons terms in the action. We find new anomalous and non anomalous transport coefficients, as well as new contributions to the existing ones coming from the mixed gauge-gravitational anomaly. Consequences for the shear waves dispersion relation are analyzed. Talk given by E. Megías at the International Nuclear Physics Conference INPC 2013, 2-7 June 2013, Firenze, Italy.Supported by Plan Nacional de Altas Energías (FPA2009-07908, FPA2011-25948), Spanish MICINN Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042), Comunidad de Madrid HEP-HACOS S2009/ESP-1473, Spanish MINECO's Centro de Excelencia Severo Ochoa Program (SEV-2012-0234, SEV-2012-0249), and the Juan de la Cierva Program.
Inference of Altimeter Accuracy on Along-track Gravity Anomaly Recovery
LI Yang
2015-04-01
Full Text Available A correlation model between along-track gravity anomaly accuracy, spatial resolution and altimeter accuracy is proposed. This new model is based on along-track gravity anomaly recovery and resolution estimation. Firstly, an error propagation formula of along-track gravity anomaly is derived from the principle of satellite altimetry. Then the mathematics between the SNR (signal to noise ratio and cross spectral coherence is deduced. The analytical correlation between altimeter accuracy and spatial resolution is finally obtained from the results above. Numerical simulation results show that along-track gravity anomaly accuracy is proportional to altimeter accuracy, while spatial resolution has a power relation with altimeter accuracy. e.g., with altimeter accuracy improving m times, gravity anomaly accuracy improves m times while spatial resolution improves m0.4644 times. This model is verified by real-world data.
The 2017 solar eclipse and Majorana & Allais gravity anomalies
Munera, Hector A.
2017-01-01
Two little known anomalies hint to phenomena beyond current theory. Majorana effect: around 1920 in a series of well-designed experiments with a chemical laboratory balance, Quirino Majorana found in Italy that mercury (Hg) and lead (Pb) might shield terrestrial gravity. Majorana experiments were never repeated by the international scientific community. Instead his results were dismissed on theoretical claims: a) unobserved heating of earth by absorption of gravity, and b) unobserved cyclic lunar perturbation of solar gravity at earth’s surface. However, Majorana critics missed the crucial fact that shielding is not mere absorption, but also scattering, and that atomic number Z of matter in the moon is much lower than Z=80 (Hg) and Z=82 (Pb). From the June 30/1954 solar eclipse onwards, high-quality mechanical gravimeters were used to search for Majorana shielding by the moon. Results are positive, provided that shielding is interpreted as scattering rather than absorption of gravity by moon (H. A. Munera, Physics Essays 24, 428-434, 2011). Allais effect: during the same 1954 eclipse (partial in Paris) Maurice Allais had in operation a sensitive paraconical pendulum for a very different purpose. Surprisingly, the pendulum was perturbed by the eclipse, condition repeated once again in a 1959 solar eclipse, also partial in Paris. During the past sixty years, paraconical, torsion and Foucault pendula, and other mechanical devices, have been used to (dis)confirm Allais effect, but the results are not conclusive thus far. A book edited by this author (Should the laws of gravitation be revised? Apeiron 2011) describes some of those observations. Various unexpected effects, some of them torsional, appear both near the optical shadow, and far away. The Sun-Moon-Earth alignment in a solar eclipse allows detection on the terrestrial surface of the dark matter flow scattered on moon’s surface (flow not hitting earth in other geometries). Rotation of moon may induce
Gauge Symmetries and Holographic Anomalies of Chern-Simons and Transgression AdS Gravity
Mora, Pablo
2014-01-01
We review the issue of gauge and gravitational anomalies with backgrounds, maybe offering a new outlook on some aspects of these questions. We compute the holographic anomalies of hypothetical theories dual, in the sense of the AdS-CFT correspondence, to Chern-Simons AdS gravities. Those anomalies are either gauge anomalies associated to the AdS gauge group of the theory or diffeomorphism anomalies, with each kind related to the other. As a result of using suitable action principles por Chern-Simons AdS gravities, coming from Transgression forms, we obtain finite results without the need for further regularization. Our results are of potential interest for Lovelock gravity theories, as it has been shown that the boundary terms dictated by the transgressions for Chern-Simons gravities are also suitable to regularize Lovelock theories. The Wess-Zumino consistency condition ensures that anomalies of the generic form computed here should appear for these and other theories.
Calculating the Marine Gravity Anomaly of the South China Sea based on the Inverse Stokes Formula
Liu, Liang; Jiang, Xiaoguang; Liu, Shanwei; Zheng, Lei; Zang, Jinxia; Zhang, Xuehua; Liu, Longfei
2016-11-01
Marine gravity field information has a great significance for the resource, environment and military affairs. As a new way to get marine gravity data, the satellite altimetry technique makes up for what ship measuring means lack. The paper carries out the researches on how altimeter data applied for calculating marine gravity anomaly based on inverse Stokes formula. In the article, the editing of 14-track Jason-1 data over South China Sea for 7 years is for collinear processing and cross-point adjustment. The inverse Stokes formula and fast Flourier transform technique are applied to calculate marine gravity anomaly of the region (0°∼23°N, 103°∼120°E), and to draw gravity anomaly map. Compared with the gravity anomaly by ship observation, RMS is 12.6mGal, and single altimetry satellite has a good precision.
Hurtado-Cardador, Manuel; Urrutia-Fucugauchi, Jaime
2006-12-01
Since 1947 Petroleos Mexicanos (Pemex) has conducted oil exploration projects using potential field methods. Geophysical exploration companies under contracts with Pemex carried out gravity anomaly surveys that were referred to different floating data. Each survey comprises observations of gravity stations along highways, roads and trails at intervals of about 500 m. At present, 265 separate gravimeter surveys that cover 60% of the Mexican territory (mainly in the oil producing regions of Mexico) are available. This gravity database represents the largest, highest spatial resolution information, and consequently has been used in the geophysical data compilations for the Mexico and North America gravity anomaly maps. Regional integration of gravimeter surveys generates gradients and spurious anomalies in the Bouguer anomaly maps at the boundaries of the connected surveys due to the different gravity base stations utilized. The main objective of this study is to refer all gravimeter surveys from Pemex to a single new first-order gravity base station network, in order to eliminate problems of gradients and spurious anomalies. A second objective is to establish a network of permanent gravity base stations (BGP), referred to a single base from the World Gravity System. Four regional loops of BGP covering eight States of Mexico were established to support the tie of local gravity base stations from each of the gravimeter surveys located in the vicinity of these loops. The third objective is to add the gravity constants, measured and calculated, for each of the 265 gravimeter surveys to their corresponding files in the Pemex and Instituto Mexicano del Petroleo database. The gravity base used as the common datum is the station SILAG 9135-49 (Latin American System of Gravity) located in the National Observatory of Tacubaya in Mexico City. We present the results of the installation of a new gravity base network in northeastern Mexico, reference of the 43 gravimeter surveys
Tsoulis, Dimitrios; Patlakis, Konstantinos
2017-04-01
Gravity reductions and gravity anomalies express important tools for the analysis and interpretation of real gravity measurements at all spatial scales. Simple geometries of planar or spherical slabs for the topographic masses underlying the computation point down to a reference height surface produce the traditional definition of simple Bouguer anomalies. However, especially for gravity measurements obtained from local gravity surveys stretching up to only a few tens of kilometers, a detailed consideration of the deviations of the surface topographic relief from the ideal slab geometry is required and necessary in order to obtain the so-called refined Bouguer anomalies. The present contribution examines the further refinement of these computations depending on the exact geometric representation of the topographic surface and the corresponding masses defining the terrain correction quantity. Using as input data 328 surface gravity observations and a 20 km x 15 km Digital Terrain Model with a 50 m x 50 m spatial resolution of a steep terrain area in the Bavarian Alps different sets of gravity anomalies were computed from different geometrical and mathematical approximations of the topographic masses and its corresponding gravitational effect. Right rectangular prisms, polyhedrons, bilinear surfaces, mass-line and mass-prism FFT representations of the terrain effect have been implemented for the evaluation of refined Bouguer gravity anomalies over the 20 km x 15 km region and the computed grids have been compared both against each other as well as with respect to the topographic height.
Gravity anomalies and crustal structure of the Bay of Bengal
Subrahmanyam, V; Krishna, K.S.; Murthy, I.V; Sarma, K.V.L; Desa, M.; Ramana, M.V; KameshRaju, K.A.
The Bengal Fan is covered afresh by systematic geological and geophysical investigations by National Institute of Oceanography (NIO), India and a detailed free-air gravity map of the fan is prepared. The map shows two strong gravity lows - one...
Revised estimation of 550-km times 550-km mean gravity anomalies
Williamson, M. R.
1977-01-01
The calculation of 550-km x 550-km mean gravity anomalies from 1 degree x 1 degree mean free-air gravimetry data is discussed. The block estimate procedure developed by Kaula is used to obtain 1,504 of the 1,654 possible mean block anomalies. The estimated block anomalies calculated from 1 deg x 1 deg mean anomalies referred to the reference ellipsoid and from 1 degree x 1 degree mean anomalies referred to a 24th-degree-and-order field are compared.
Gravity anomalies, plate tectonics and the lateral growth of Precambrian North America
Thomas, M. D.; Grieve, R. A. F.; Sharpton, V. L.
1988-01-01
The widespread gravity coverage of North America provides a picture of the gross structural fabric of the continent via the trends of gravity anomalies. The structural picture so obtained reveals a mosaic of gravity trend domains, many of which correlate closely with structural provinces and orogenic terranes. The gravity trend map, interpreted in the light of plate-tectonic theory, thus provides a new perspective for examining the mode of assembly and growth of North America. Suture zones, palaeosubduction directions, and perhaps, contrasting tectonic histories may be identified using gravity patterns.
Gravity anomalies, plate tectonics and the lateral growth of Precambrian North America
Thomas, M. D.; Grieve, R. A. F.; Sharpton, V. L.
1988-01-01
The widespread gravity coverage of North America provides a picture of the gross structural fabric of the continent via the trends of gravity anomalies. The structural picture so obtained reveals a mosaic of gravity trend domains, many of which correlate closely with structural provinces and orogenic terranes. The gravity trend map, interpreted in the light of plate-tectonic theory, thus provides a new perspective for examining the mode of assembly and growth of North America. Suture zones, palaeosubduction directions, and perhaps, contrasting tectonic histories may be identified using gravity patterns.
Analyses on Origin of positive gravity anomalies of sedimentary basins of the Ross Sea
Gao, Jinyao; Yang, Chunguo; Ji, Fei; Wang, Wei; Shen, Zhongyan
2017-04-01
We have adopted gridded products describing surface elevation, ice-thickness and the sea floor and subglacial bed elevation south of 60◦ S from Bedmap2 and north of 60◦ S from JGP95E to calculate Bouguer and isostatic gravity anomaly of the Ross Sea region based on the DTU10 free-air gravity anomaly.Taking a view of the free-air, Bouguer and isostatic gravity anomalies, it is unusual that high values overlay the Victoria Land Basin, Central Trough, Northern Basin and Northern Central Trough while basement highs are associated with low value. A number of studies have attributed the high gravity anomalies across the depocenters to high-density volcanics deep within the basins or magmatic intrusions within the region of the thinned crust or upper mantle (e. g., Edwards et al., 1987). According to the conclusion from Karner et al. (2005), the anticorrelation of gravity anomalies with sediment basement can be reproduced if the flexural strength of the lithosphere during the late Cretaceous rifting is significantly lower than the flexural strength of the lithosphere at the Oligocene and Neogene time of sedimentation. We note that the isostatic gravity anomalies are higher than the free-air gravity anomalies adjacent to the Transantarctic Mountains, and vice versa away from the Transantarctic Mountains. We may ignore the constraints offered by the tranditional isostasy in the local gravity studies of the Ross Sea basins, especially advancing the concept of high density material in the lower crust or upper mantle. In particular, the modeled gravity does not laterally integrate to zero, due to the existence of unbalanced forces induced by mantle. Along the outer shelf uplift zone surrouding Antarctica, the positive gravity belt has higher values in free-air gravity anomalies than those in isostatic gravity anomalies. Meanwhile, the positive gravity belt of isostatic gravity anomalies almost disappears in the background anomalies of 20 mGal to 10 mGal facing the
Long wavelength gravity anomalies over India: Crustal and lithospheric structures and its flexure
Tiwari, V. M.; Ravi Kumar, M.; Mishra, D. C.
2013-07-01
Long wavelength gravity anomalies over India were obtained from terrestrial gravity data through two independent methods: (i) wavelength filtering and (ii) removing crustal effects. The gravity fields due to the lithospheric mantle obtained from two methods were quite comparable. The long wavelength gravity anomalies were interpreted in terms of variations in the depth of the lithosphere-asthenosphere boundary (LAB) and the Moho with appropriate densities, that are constrained from seismic results at certain points. Modeling of the long wavelength gravity anomaly along a N-S profile (77°E) suggest that the thickness of the lithosphere for a density contrast of 0.05 g/cm3 with the asthenosphere is maximum of ˜190 km along the Himalayan front that reduces to ˜155 km under the southern part of the Ganga and the Vindhyan basins increasing to ˜175 km south of the Satpura Mobile belt, reducing to ˜155-140 km under the Eastern Dharwar craton (EDC) and from there consistently decreasing south wards to ˜120 km under the southernmost part of India, known as Southern Granulite Terrain (SGT). The crustal model clearly shows three distinct terrains of different bulk densities, and thicknesses, north of the SMB under the Ganga and the Vindhyan basins, and south of it the Eastern Dharwar Craton (EDC) and the Southern Granulite Terrain (SGT) of bulk densities 2.87, 2.90 and 2.96 g/cm3, respectively. It is confirmed from the exposed rock types as the SGT is composed of high bulk density lower crustal rocks and mafic/ultramafic intrusives while the EDC represent typical granite/gneisses rocks and the basement under the Vindhyan and Ganga basins towards the north are composed of Bundelkhand granite massif of the lower density. The crustal thickness along this profile varies from ˜37-38 km under the EDC, increasing to ˜40-45 km under the SGT and ˜40-42 km under the northern part of the Ganga basin with a bulge up to ˜36 km under its southern part. Reduced lithospheric and
Gravity anomalies and basement structure in Osaka plain; Osaka heiya no juryoku ijo to kiban kozo
Inoue, N.; Nakagawa, K. [Osaka City University, Osaka (Japan). Faculty of Science; Ryoki, K. [Osaka Polytechnical College, Osaka (Japan)
1998-02-01
Many kinds of new information about the underground structure are necessary for elucidating problems on the distribution characteristics of the structural damage and the ground failure due to the 1995 Hyogo-ken Nanbu Earthquake. The gravity anomalies in and around the Osaka sedimentary basin, which is mainly composed of Mesozoic granitic basement and post Tertiary sedimentary layers covering the basement, has been compiled with the data additional gravity measurements in the Hanshin-Osaka area. Basement configuration plays the important role in concentration or dispersion of seismic waves. In general, trends of the gravity anomalies should be removed from obtained gravity anomalies in order to estimate the sub-surface structures. The local free-air anomalies, which are residual anomalies obtained by applying regression technique to regional trends, exhibit linear relationship with the depth to the basement surface. In this study, therefore, the underground structure of the Osaka basin was estimated from the local free-air anomalies. First approximate model of basement surface was constructed by means of the method mentioned above, based upon the two layer (basement rock and the sedimentary cover) model. Further three dimensional model was developed based on the characteristic distribution of density inferred from seismic exploration analysis. 19 refs., 21 figs., 1 tab.
Kusznir, Nick; Gozzard, Simon; Alvey, Andy
2016-04-01
The distribution of ocean crust and lithosphere within the South China Sea (SCS) are controversial. Sea-floor spreading re-orientation and ridge jumps during the Oligocene-Miocene formation of the South China Sea led to the present complex distribution of oceanic crust, thinned continental crust, micro-continents and volcanic ridges. We determine Moho depth, crustal thickness and continental lithosphere thinning (1- 1/beta) for the South China Sea using a gravity inversion method which incorporates a lithosphere thermal gravity anomaly correction (Chappell & Kusznir, 2008). The gravity inversion method provides a prediction of ocean-continent transition structure and continent-ocean boundary location which is independent of ocean isochron information. A correction is required for the lithosphere thermal gravity anomaly in order to determine Moho depth accurately from gravity inversion; the elevated lithosphere geotherm of the young oceanic and rifted continental margin lithosphere of the South China Sea produces a large lithosphere thermal gravity anomaly which in places exceeds -150 mGal. The gravity anomaly inversion is carried out in the 3D spectral domain (using Parker 1972) to determine 3D Moho geometry and invokes Smith's uniqueness theorem. The gravity anomaly contribution from sediments assumes a compaction controlled sediment density increase with depth. The gravity inversion includes a parameterization of the decompression melting model of White & McKenzie (1999) to predict volcanic addition generated during continental breakup lithosphere thinning and seafloor spreading. Public domain free air gravity anomaly, bathymetry and sediment thickness data are used in this gravity inversion. Using crustal thickness and continental lithosphere thinning factor maps with superimposed shaded-relief free-air gravity anomaly, we improve the determination of pre-breakup rifted margin conjugacy, rift orientation and sea-floor spreading trajectory. SCS conjugate margins
Conformal anomaly and off-shell extensions of gravity
Meissner, Krzysztof A.; Nicolai, Hermann
2017-08-01
The gauge dependence of the conformal anomaly for spin-3/2 and spin-2 fields in nonconformal supergravities has been a long standing puzzle. In this paper we argue that the "correct" gauge choice is the one that follows from requiring all terms that would imply a violation of the Wess-Zumino consistency condition to be absent in the counterterm, because otherwise the usual link between the anomaly and the one-loop divergence becomes invalid. Remarkably, the "good" choice of gauge is the one that confirms our previous result [K. A. Meissner and H. Nicolai, Phys. Lett. B 772, 169 (2017)., 10.1016/j.physletb.2017.06.031] that a complete cancellation of conformal anomalies in D =4 can only be achieved for N -extended (Poincaré) supergravities with N ≥5 .
On the recovery of gravity anomalies from high precision altimeter data
Lelgemann, D.
1976-01-01
A model for the recovery of gravity anomalies from high precision altimeter data is derived which consists of small correction terms to the inverse Stokes' formula. The influence of unknown sea surface topography in the case of meandering currents such as the Gulf Stream is discussed. A formula was derived in order to estimate the accuracy of the gravity anomalies from the known accuracy of the altimeter data. It is shown that for the case of known harmonic coefficients of lower order the range of integration in Stokes inverse formula can be reduced very much.
Phenomenology of Quantum Gravity and its Possible Role in Neutrino Anomalies
Acero, Mario A
2012-01-01
New phenomenological models of Quantum Gravity have suggested that a Lorentz-Invariant discrete spacetime structure may become manifest through a nonstandard coupling of matter fields and spacetime curvature. On the other hand, there is strong experimental evidence suggesting that neutrino oscillations cannot be described by simply considering neutrinos as massive particles. In this manuscript we motivate and construct one particular phenomenological model of Quantum Gravity that could account for the so-called neutrino anomalies.
Spherical earth gravity and magnetic anomaly analysis by equivalent point source inversion
Von Frese, R. R. B.; Hinze, W. J.; Braile, L. W.
1981-01-01
To facilitate geologic interpretation of satellite elevation potential field data, analysis techniques are developed and verified in the spherical domain that are commensurate with conventional flat earth methods of potential field interpretation. A powerful approach to the spherical earth problem relates potential field anomalies to a distribution of equivalent point sources by least squares matrix inversion. Linear transformations of the equivalent source field lead to corresponding geoidal anomalies, pseudo-anomalies, vector anomaly components, spatial derivatives, continuations, and differential magnetic pole reductions. A number of examples using 1 deg-averaged surface free-air gravity anomalies of POGO satellite magnetometer data for the United States, Mexico, and Central America illustrate the capabilities of the method.
Bowin, C.
1982-01-01
A negative free-air gravity anomaly which occurs in the central part of the Philippine Sea was examined to determine the distribution and nature of possible regional mass excesses or deficiencies. Geoid anomalies from GEOS-3 observation were positive. A negative residual geoid anomaly consistent with the area of negative free-air gravity anomalies were found. Theoretical gravity-topography and geoid-topography admittance functions indicated that high density mantle at about 60 km dept could account for the magnitudes of the gravity and residual geoid anomaly and the 1 km residual water depth anomaly in the Philippine Sea. The negative residual depth anomaly may be compensated for by excess density in the uppermost mantle, but the residual geoid and regional free-air gravity anomalies and a slow surface wave velocity structure might result from low-density warm upper mantle material lying beneath the zone of high-density uppermost mantle. From a horizontal disk approximation, the depth of the low-density warm mantle was estimated to be on the order of 200 km.
The estimation of 550 km x 550 km mean gravity anomalies. [from free atmosphere gravimetry data
Williamson, M. R.; Gaposchkin, E. M.
1975-01-01
The calculation of 550 km X 550 km mean gravity anomalies from 1 degree X 1 degree mean free-air gravimetry data is discussed. The block estimate procedure developed by Kaula was used, and estimates for 1452 of the 1654 blocks were obtained.
MULTI-SCALE DECOMPOSITION OF BOUGUER GRAVITY ANOMALY AND SEISMIC ACTIVITY IN NORTH CHINA
FangShengming; ZhangXiankang; JiaShixu; DuanYonghong; YangZhuoxin; QiuShuyan
2003-01-01
Bouguer gravity anomaly in North China is decomposed with multi-scale decomposition technique of wavelet transform. Gravity anomalies produced by anomalous density bodies of various scales are revealed from surface to Moho. Characteristics of anomalies of different orders and corresponding structural features are discussed. The result shows that details of wavelet transform of different orders reflect the distribution features of rock density at different depths and in various scales. In most cases, the two sides of a fault-especially a deep and large fault-in North China differ greatly in rock density. This difference records the history of the formation and evolution of the crust. Deep structural setting for the Ms≥7.0 strong earthquakes in this region is also discussed.
World Gravity Map: a set of global complete spherical Bouguer and isostatic anomaly maps and grids
Bonvalot, S.; Balmino, G.; Briais, A.; Kuhn, M.; Peyrefitte, A.; Vales, N.; Biancale, R.; Gabalda, G.; Reinquin, F.
2012-04-01
We present here a set of digital maps of the Earth's gravity anomalies (surface free air, Bouguer and isostatic), computed at Bureau Gravimetric International (BGI) as a contribution to the Global Geodetic Observing Systems (GGOS) and to the global geophysical maps published by the Commission for the Geological Map of the World (CGMW) with support of UNESCO and other institutions. The Bouguer anomaly concept is extensively used in geophysical interpretation to investigate the density distributions in the Earth's interior. Complete Bouguer anomalies (including terrain effects) are usually computed at regional scales by integrating the gravity attraction of topography elements over and beyond a given area (under planar or spherical approximations). Here, we developed and applied a worldwide spherical approach aimed to provide a set of homogeneous and high resolution gravity anomaly maps and grids computed at the Earth's surface, taking into account a realistic Earth model and reconciling geophysical and geodetic definitions of gravity anomalies. This first version (1.0) has been computed by spherical harmonics analysis / synthesis of the Earth's topography-bathymetry up to degree 10800. The detailed theory of the spherical harmonics approach is given in Balmino et al., (Journal of Geodesy, 2011). The Bouguer and terrain corrections have thus been computed in spherical geometry at 1'x1' resolution using the ETOPO1 topography/bathymetry, ice surface and bedrock models from the NOAA (National Oceanic and Atmospheric Administration) and taking into account precise characteristics (boundaries and densities) of major lakes, inner seas, polar caps and of land areas below sea level. Isostatic corrections have been computed according to the Airy-Heiskanen model in spherical geometry for a constant depth of compensation of 30km. The gravity information given here is provided by the Earth Geopotential Model (EGM2008), developed at degree 2160 by the National Geospatial
Ryzhii, B. P.; Nachapkin, N. I.; Milanovsky, S. Yu.
2003-04-01
According developed concept the areas heightened intraplate seismicity are connected with the increased silica contents in the rocks, i.e. with patterns of acidic composition and, accordingly, with negative Bouguer gravity anomalies. Done statistical analysis of intraplate allocation of earthquakes on territory of Russia, Africa and Australia has confirmed effect of correlation of their position with areas of negative Bouguer anomalies. In this paper we made pattern analysis of the link of areas heightened intraplate seismicity for South and North America with anomalies of a gravity field - Bouguer and isostatic. If Bouguer anomalies are mainly related to morphology and composition of structural complexes of Earth crust, the isostatic anomalies, as a rule, are connected with acting tectonic forces and characterize a modern stress of Earth crust. For South America we analyzed 139 seismic events, which have occurred in a crust of Brazilian Platform in the period from 1692 to 2002. In regions with negative values of Bouguer anomalies, smaller than its mean for the Platform (-30 mgal), there occur 70% of all earthquakes. The correlation of a magnitude and depth of a hypocenter of earthquake is supervised depending on the value of Bouguer anomalies in its epicenter. In regions with positive values of isostatic anomaly, larger its mean magnitude for the Platform (1 mgal), there occur 77 % of all earthquakes. For North America we analyzed 383 seismic events which have occurred in a crust of North-American Platform in a period with 1929 on 2002. From 383 events 288 (75 %) has taken place in areas with negative values of Bouguer anomalies and 95 (25 %) - with positive values. Thus, the amount of earthquakes recorded in a negative gravitational field, in 4 times exceeds an amount of earthquakes in a positive field. At values of isostatic anomalies close to normal (-10 - 10 mgal) there was 55 % of all earthquakes and 41 % - recorded in ecstatically disturbed regions at values
Gravity Anomalies of Arbitrary 3D Polyhedral Bodies with Horizontal and Vertical Mass Contrasts
Ren, Zhengyong; Chen, Chaojian; Pan, Kejia; Kalscheuer, Thomas; Maurer, Hansruedi; Tang, Jingtian
2017-03-01
During the last 15 years, more attention has been paid to derive analytic formulae for the gravitational potential and field of polyhedral mass bodies with complicated polynomial density contrasts, because such formulae can be more suitable to approximate the true mass density variations of the earth (e.g., sedimentary basins and bedrock topography) than methods that use finer volume discretization and constant density contrasts. In this study, we derive analytic formulae for gravity anomalies of arbitrary polyhedral bodies with complicated polynomial density contrasts in 3D space. The anomalous mass density is allowed to vary in both horizontal and vertical directions in a polynomial form of λ =ax^m+by^n+cz^t, where m, n, t are nonnegative integers and a, b, c are coefficients of mass density. First, the singular volume integrals of the gravity anomalies are transformed to regular or weakly singular surface integrals over each polygon of the polyhedral body. Then, in terms of the derived singularity-free analytic formulae of these surface integrals, singularity-free analytic formulae for gravity anomalies of arbitrary polyhedral bodies with horizontal and vertical polynomial density contrasts are obtained. For an arbitrary polyhedron, we successfully derived analytic formulae of the gravity potential and the gravity field in the case of m≤ 1, n≤ 1, t≤ 1, and an analytic formula of the gravity potential in the case of m=n=t=2. For a rectangular prism, we derive an analytic formula of the gravity potential for m≤ 3, n≤ 3 and t≤ 3 and closed forms of the gravity field are presented for m≤ 1, n≤ 1 and t≤ 4. Besides generalizing previously published closed-form solutions for cases of constant and linear mass density contrasts to higher polynomial order, to our best knowledge, this is the first time that closed-form solutions are presented for the gravitational potential of a general polyhedral body with quadratic density contrast in all spatial
Yokoyama, I.; Mena, M.
1991-07-01
Previous studies of La Primavera caldera have mostly been based on surface geology and topography. Since 1980, many wells, exploring for geothermal energy, have reached depths of about 2 to 3 km at the center of the caldera. The results of the drillings, together with those of the gravity surveys, provide information about the subsurface structure of the caldera, and shed light on its formation. The drilling results and gravity anomalies at La Primavera caldera and San Marcos, located at about 40 km distance from the caldera, suggest that regional gravity anomalies can be interpreted in terms of depths of the granitic basements: the basement beneath La Primavera caldera is about 3 km deep and consists of roughly the same horizon as that beneath San Marcos. The drilling results within the caldera reveal that the depth of the caldera fills ranges from 0.3 to 1 km at the drilling sites. The andesite basement, about 1 km deep, remains approximately horizontal, and the granitic basement has a depth of about 3 km. The surface topographies, such as the postcaldera domes, scarcely disturb the subsurface strata. The local gravity anomalies show two lows within the caldera reflecting the configuration of caldera bottom, two funnel-shaped depressions, one of which corresponds to a vent of the Tala tuff deduced from geological observations. The mass deficiency within the caldera estimated from the gravity anomaly, satisfies the general relationship that the mass deficiency is proportional to the caldera diameter cubed. This means that caldera structure is three-dimensional: the larger the diameter, the deeper the funnel-shape. At present this argument may be limited to funnel-shaped calderas.
General proof of (maximum) entropy principle in Lovelock gravity
Cao, Li-Ming
2014-01-01
We consider a static self-gravitating perfect fluid system in Lovelock gravity theory. For a spacial region on the hypersurface orthogonal to static Killing vector, by the Tolman's law of temperature, the assumption of a fixed total particle number inside the spacial region, and all of the variations (of relevant fields) in which the induced metric and its first derivatives are fixed on the boundary of the spacial region, then with the help of the gravitational equations of the theory, we can prove a theorem says that the total entropy of the fluid in this region takes an extremum value. A converse theorem can also be obtained following the reverse process of our proof.
General proof of (maximum) entropy principle in Lovelock gravity
Cao, Li-Ming; Xu, Jianfei
2015-02-01
We consider a static self-gravitating perfect fluid system in Lovelock gravity theory. For a spacial region on the hypersurface orthogonal to static Killing vector, by the Tolman's law of temperature, the assumption of a fixed total particle number inside the spacial region, and all of the variations (of relevant fields) in which the induced metric and its first derivatives are fixed on the boundary of the spacial region, then with the help of the gravitational and fluid equations of the theory, we can prove a theorem says that the total entropy of the fluid in this region takes an extremum value. A converse theorem can also be obtained following the reverse process of our proof. We also propose the definition of isolation quasilocally for the system and explain the physical meaning of the boundary conditions in the proof of the theorems.
Anomalies and Hawking fluxes from the black holes of topologically massive gravity
Porfyriadis, Achilleas P
2009-01-01
The anomaly cancelation method proposed by Wilczek et al. is applied to the black holes of topologically massive gravity (TMG) and topologically massive gravito-electrodynamics (TMGE). Thus the Hawking temperature and fluxes of the ACL and ACGL black holes are found. The Hawking temperatures obtained agree with the surface gravity formula. Both black holes are rotating and this gives rise to appropriate terms in the effective U(1) gauge field of the reduced (1+1)-dimensional theory. It is found that the terms in this U(1) gauge field correspond exactly to the correct angular velocities on the horizon of both black holes as well as the correct electrostatic potential of the ACGL black hole. So the results for the Hawking fluxes derived here from the anomaly cancelation method, are in complete agreement with the ones obtained from integrating the Planck distribution.
Herceg, Matija; Artemieva, Irina; Thybo, Hans
2013-01-01
We investigate the effect of the crustal structure heterogeneity and uncertainty in its determination on stripped gravity field. The analysis is based on interpretation of residual upper mantle gravity anomalies which are calculated by subtracting (stripping) the gravitational effect of the crust...... (including topography) from the observed satellite gravity field data (GOCE Direct release 3). We apply our analysis to Siberia for which a new regional crustal model has recently become available. Uncertainties in the residual upper (lithospheric) mantle gravity anomalies result from several sources: (i...
Joint Interpretation of Bathymetric and Gravity Anomaly Maps Using Cross and Dot-Products.
Jilinski, Pavel; Fontes, Sergio Luiz
2010-05-01
0.1 Summary We present the results of joint map interpretation technique based on cross and dot-products applied to bathymetric and gravity anomaly gradients maps. According to the theory (Gallardo, Meju, 2004) joint interpretation of different gradient characteristics help to localize and empathize patterns unseen on one image interpretation and gives information about the correlation of different spatial data. Values of angles between gradients and their cross and dot-product were used. This technique helps to map unseen relations between bathymetric and gravity anomaly maps if they are analyzed separately. According to the method applied for the southern segment of Eastern-Brazilian coast bathymetrical and gravity anomaly gradients indicates a strong source-effect relation between them. The details of the method and the obtained results are discussed. 0.2 Introduction We applied this method to investigate the correlation between bathymetric and gravity anomalies at the southern segment of the Eastern-Brazilian coast. Gridded satellite global marine gravity data and bathymetrical data were used. The studied area is located at the Eastern- Brazilian coast between the 20° W and 30° W meridians and 15° S and 25° S parallels. The volcanic events responsible for the uncommon width of the continental shelf at the Abrolhos bank also were responsible for the formation of the Abrolhos islands and seamounts including the major Vitoria-Trindade chain. According to the literature this volcanic structures are expected to have a corresponding gravity anomaly (McKenzie, 1976, Zembruscki, S.G. 1979). The main objective of this study is to develop and test joint image interpretation method to compare spatial data and analyze its relations. 0.3 Theory and Method 0.3.1 Data sources The bathymetrical satellite data were derived bathymetry 2-minute grid of the ETOPO2v2 obtained from NOAA's National Geophysical Data Center (http://www.ngdc.noaa.gov). The satellite marine gravity 1
Application of 3D variation-density interface inversion of gravity anomalies in South China Sea
Li, Shuling; Meng, Xiaohong
2017-04-01
The South China Sea (SCS) is a marginal basin with extremely complicated crustal structure and whose evolutional history is associated with continental rifting and seafloor spreading. The gravity data are among the most important data sets for studying deep crustal structures and the tectonic evolution. Density interface inversion by gravity anomalies can effectively estimate the depth of Moho interface. However, the Moho interface inversion in SCS are facing challenges due to the density contract of crust-mantle vary in three dimensions, which are associated with the complicated crustal structure (co-existing oceanic crust, continental crust and transitional crust). The regular inversion methods always assume the density contract on both sides of the interface would be constant, which is quite unrealistic since actual strata densities vary both vertically and laterally. To meet the challenges of 3D variation of density in SCS, we present an improved 3D variation-density interface inversion of gravity anomalies based on Parker-Oldenburg method. We first construct two variation density models with exponential density-depth relationships, which expressed the variation of stratum density depending on the depth in oceanic and continental crust respectively. Meanwhile, to minimize multiple solutions for potential field inversion, we collect deep seismic sounding data and employ the gravity inversion by joint using seismic data to be constraint for depth of Moho. Finally, we have estimated the depth of Moho interface which infers the tectonic significance in SCS. The inversion results agree well with seismic data in SCS show this approach is more effective and precise to quantitative estimate the depth of interface. Keywords: South China Sea; Gravity anomalies; Density interface inversion;
Processing and interpretation of gravity anomaly data in Dagang-west Bohai area
Hualin, Z.; Hua, Y
1991-01-01
In the area of Dagang oil field and west Bohai oil field, there exist three major density interfaces: S{sub 1} interface between Cenozoic group and Mesozoic group (or upper Paleozoic group), S{sub 2} interface between Mesozoic-group (or upper Paleozoic group) and lower Paleozoic group, and S{sub 3} interface-Moho (Mohorovicic discontinuity). Gravimetric Bouguer anomaly in this area is actually the sum of the anomalies which result from the three interfaces. The author's objective is to ascertain the depth of S{sub 2} interface (the top of lower Paleozoic group) by separating out S{sub 2} interface anomaly from existing Bouguer anomaly map. This is achieved in the following steps. First gravity values {Beta}g{sub s{sub 1}} and {Beta}g{sub s{sub 3}} which result from S{sub 1} and S{sub 3} interfaces are calculated respectively by making forward modeling with the use of linear element method. Then, gravity value {Beta}g{sub s{sub 2}} corresponding to S{sub 2} interface is obtained by subtracting {Beta}g{sub s{sub 1}} and {Beta}s{sub s{sub 3}} from the total observed gravity value. Finally, the depth of S{sub 2} interface can be ascertained by making inverse modeling of {Beta}g{sub s{sub 2}} with the use of Cordell's method. This calculated depth quite agrees with those which are determined respectively from seismic reflection survey and drilling.
The New Gravity System: Changes in International Gravity Base Values and Anomaly Values
1980-10-01
Johannesburg and Capetown , and that the apparent resulting slope defined is fortuitously reinforced by a poor gravity connection between Khartoum and...is indicated by the data for the West African series. This series (Section C) indicates that all values from Madrid through to Capetown except that...mrea) is much the same as that for the northern sector of the mid-continent East Africa series (14.75 mgal) , and since the Capetown value would only
National Aeronautics and Space Administration — PROBABILITY CALIBRATION BY THE MINIMUM AND MAXIMUM PROBABILITY SCORES IN ONE-CLASS BAYES LEARNING FOR ANOMALY DETECTION GUICHONG LI, NATHALIE JAPKOWICZ, IAN HOFFMAN,...
The maximum sizes of large scale structures in alternative theories of gravity
Bhattacharya, Sourav; Romano, Antonio Enea; Skordis, Constantinos; Tomaras, Theodore N
2016-01-01
The maximum size of a cosmic structure is given by the maximum turnaround radius -- the scale where the attraction due to its mass is balanced by the repulsion due to dark energy. We derive generic formulas for the estimation of the maximum turnaround radius in any theory of gravity obeying the Einstein equivalence principle, in two situations: on a spherically symmetric spacetime and on a perturbed Friedman-Robertson-Walker spacetime. We show that the two formulas agree. As an application of our formula, we calculate the maximum turnaround radius in the case of the Brans-Dicke theory of gravity. We find that for this theory, such maximum sizes always lie above the $\\Lambda$CDM value, by a factor $1 + \\frac{1}{3\\omega}$, where $\\omega\\gg 1$ is the Brans-Dicke parameter, implying consistency of the theory with current data.
Chakravarthi, V.; Mallesh, K.; Ramamma, B.
2017-03-01
We develop two automatic techniques in the spatial domain using the exponential density contrast model (EDCM) to trace the bottom surface of a 2.5D sedimentary basin from the observed gravity anomalies. The interface between the sediments and basement is described with a finite strike polygonal source, whose depth ordinates become the unknown parameters to be estimated. The proposed automatic modeling technique makes use of the forward difference approximation and the inversion solves a system of normal equations using the ridge regression to estimate the unknown parameters. Furthermore, the proposed inversion technique simultaneously estimates the regional gravity background that is associated with the residual gravity anomaly. In either case, forward modeling is realized in the spatial domain through a method that combines both analytical and numerical approaches. The utility of each algorithm was successfully tested on a theoretically produced noisy residual gravity dataset. The validity of the inversion technique is also exemplified with the noisy gravity anomalies attributable to a synthetic structure in the presence of regional gravity background. We demonstrate that the magnitude of gravity anomaly is offset dependent and that it would influence the modeling result. Additionally, some applications with real gravity datasets from the Gediz and Büyük Menderes grabens in western Turkey using the derived EDCMs have produced geologically reasonable results which are in close agreement with those reported previously.
Subrahmanyam, V.; Rao, D.G.; Ramprasad, T.; KameshRaju, K.A.; Rao, M.G.
Bathymetric and gravity data totalling 2000 line km on the continental margin off Goa and Mulki, west of India have been studied. The free-air gravity anomalies vary between -60 to 25 mgals with prominent NNW-SSE trends in the outer shelf region...
Chen, C.; Hu, Z.; Du, J.; Wang, Q.
2011-12-01
The Philippine Sea, situated in the northwestern Pacific, is one of the largest marginal seas on the Earth. Analysis of the Philippine Sea's intraplate fault tectonic systems and lithosphere's density and magnetism structures has a significant contribution to understanding not only the dynamic principles of subduction and convergence zones but also effect of plate subduction on back-arc area. It is also important to have cognizance for structure evolution of the ocean crust, the tension and extending progress of marginal sea basins and the mechanisms of geodynamics. Meanwhile, it can be a significant approach for researching the evolution of the East China Sea and the South China Sea. Using high-precision gravity forwarding method based on spatial domain in spherical coordinate, we have calculated the Bouguer gravity disturbance (BGD) in the Philippine Sea based on the ETOPO1 1 arc-minute topography & bathymetry data and the gravity field model EIGEN-6C. After removing the gravity effect of the sediments and deep abnormal materials, we make spherical cap harmonic analysis of the residual anomaly and obtain the topography of Moho and apparent-density's distribution of our study area by alternate iteration inversion method. Then, we calculate the distributions of the study area's magnetic anomalies based on the Earth magnetic model NGDC720, reduce to the pole of the study area's magnetic anomalies by the equivalent source method based on spherical prism magnetic forwarding, inverse the processed magnetic anomalies with spherical cap harmonic analysis to obtain the topography of Curie surface and the apparent magnetic susceptibility distribution. Finally, we divide the Philippine Sea block into tectonic units and derive the faults distributions through the analysis of gravity magnetic anomalies' linear characteristics. The results show that West Philippine Basin is divided by Central Basin Ridge into two block units, the tectonic trend of the north block is south
Massive torsion modes, chiral gravity and the Adler–Bell–Jackiw anomaly
Chang, L N; Chang, Lay Nam; Soo, Chopin
2003-01-01
Regularization of quantum field theories introduces a mass scale which breaks axial rotational and scaling invariances. We demonstrate from first principles that axial torsion and torsion trace modes have non-tranverse vacuum polarization tensors, and become massive as a result of the Adler-Bell-Jackiw (ABJ) and scaling anomalies. Since these are the only torsion components that can couple minimally to spin 1/2 particles, the anomalous generation of masses for these modes, naturally of the order of the regulator scale, may help to explain why torsion and its associated effects, including CPT violation in chiral gravity, have so far escaped detection. As a simpler manifestation of the ABJ anomaly than triangle diagrams, the vacuum polarization demonstration is also pedagogically useful.
Massive torsion modes, chiral gravity, and the Adler-Bell-Jackiw anomaly
Chang, L N; Chang, Lay Nam; Soo, Chopin
2003-01-01
Regularization of quantum field theories introduces a mass scale which breaks axial rotational and scaling invariances. We demonstrate from first principles that axial torsion and torsion trace modes have non-transverse vacuum polarization tensors, and become massive as a result. The underlying reasons are similar to those responsible for the Adler-Bell-Jackiw (ABJ) and scaling anomalies. Since these are the only torsion components that can couple minimally to spin 1/2 particles, the anomalous generation of masses for these modes, naturally of the order of the regulator scale, may help to explain why torsion and its associated effects, including CPT violation in chiral gravity, have so far escaped detection. As a simpler manifestation of the reasons underpinning the ABJ anomaly than triangle diagrams, the vacuum polarization demonstration is also pedagogically useful. In addition it is shown that the teleparallel limit of a Weyl fermion theory coupled only to the left-handed spin connection leads to a counter...
Finite-time singularities in f(R, T) gravity and the effect of conformal anomaly
Houndjo, M J S; Campos, J P; Piattella, O F
2012-01-01
We investigate $f(R,T)$ gravity models ($R$ is the curvature scalar and $T$ is the trace of the stress-energy tensor of ordinary matter) that are able to reproduce the four known types of future finite-time singularities. We choose a suitable expression for the Hubble parameter in order to realise the cosmic acceleration and we introduce two parameters, $\\alpha$ and $H_s$, which characterise each type of singularity. We address conformal anomaly and we observe that it cannot remove the sudden singularity or the type IV one, but, for some values of $\\alpha$, the big rip and the type III singularity may be avoided. We also find that, even without taking into account conformal anomaly, the big rip and the type III singularity may be removed thanks to the presence of the $T$ contribution of the $f(R,T)$ theory.
Higgs Mass and Muon $g-2$ Anomaly in MSSM with Gauge-Gravity hybrid Mediation
Zhu, Bin; Li, Tianjun
2016-01-01
We propose a gauge mediation model with split messengers to explain the muon $g-2$ anomaly in consistent with $125$ GeV higgs mass requirement. The special properties is that all of color sparticles masses fall into several TeV region due to the large messenger splitting which are well beyond the scope of current LHC Run II limits. Meanwhile, sleptons and electroweakinos are light enough to retain advantages of electroweak supersymmetry. This type of spectrum can be realized by introducing hybrid model which combines gauge and gravity mediation. In addition, this mechanism is also responsible for solving tachyonic problem of slepton sector.
Rossetti, Dilce de Fátima; Cassola Molina, Eder; Cremon, Édipo Henrique
2016-08-01
The Pantanal Setentrional (PS) is the second largest wetland in Brazil, occurring in a region of northern Amazonia previously regarded as part of the intracratonic Solimões Basin. However, while Paleozoic to Neogene strata are recorded in this basin, the PS constitutes a broad region with an expressive record of only Late Pleistocene and Holocene deposits. The hypothesis investigated in the present work is if these younger deposits were formed within a sedimentary basin having a geological history separated from the Solimões Basin. Due to the location in a remote region of low accessibility, the sedimentary fill of the PS wetland remains largely unknown in subsurface. In the present work, we combine geomorphological and gravity data acquired on a global basis by several satellite gravity missions to approach the geological context of this region. The results revealed a wetland characterized in surface by a low-lying terrain with wedge shape and concave-up geometry that is in sharp contact with highland areas of Precambrian rocks of the Guiana Shield. Such contact is defined by a series of mainly NE- or NW-trending straight lineaments that eventually extend into both the Guiana Shield and the PS wetland. Also of relevance is that a great part of the PS wetland sedimentary cover consists of dominantly sandy deposits preserved as residual paleo-landforms with triangular shapes previously related to megafan depositional systems. These are distributed radially at the northern margin of the PS, with axis toward basement rocks and fringes toward the wetland's center, the latter containing the largest megafan landform. The analysis of gravity anomaly data revealed a main NNE-trending chain ∼500 km in length defined by high gravity values (i.e., up to 60 mGal); these are bounded by negative anomalies as low as -90 mGal. The chain with positive gravity anomaly marks the center of a subsiding area having a geological evolution that differs from the adjacent intracratonic
Online-Offline, 1999
1999-01-01
This theme issue on anomalies includes Web sites, CD-ROMs and software, videos, books, and additional resources for elementary and junior high school students. Pertinent activities are suggested, and sidebars discuss UFOs, animal anomalies, and anomalies from nature; and resources covering unexplained phenonmenas like crop circles, Easter Island,…
Massive torsion modes, chiral gravity and the Adler-Bell-Jackiw anomaly
Chang, Lay Nam [Department of Physics, Virginia Tech., Blacksburg, VA 24061-0435 (United States); Soo Chopin [Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (China)
2003-04-07
Regularization of quantum field theories introduces a mass scale which breaks axial rotational and scaling invariances. We demonstrate from first principles that axial torsion and torsion trace modes have non-transverse vacuum polarization tensors, and become massive as a result. The underlying reasons are similar to those responsible for the Adler-Bell-Jackiw (ABJ) and scaling anomalies. Since these are the only torsion components that can couple minimally to spin-1/2 particles, the anomalous generation of masses for these modes, naturally of the order of the regulator scale, may help to explain why torsion and its associated effects, including CPT violation in chiral gravity, have so far escaped detection. As a simpler manifestation of the reasons underpinning the ABJ anomaly than triangle diagrams, the vacuum polarization demonstration is also pedagogically useful. In addition, it is shown that the teleparallel limit of a Weyl fermion theory coupled only to the left-handed spin connection leads to a counter term which is the Samuel-Jacobson-Smolin action of chiral gravity in four dimensions.
Zhang, Shengjun; Sandwell, David T.; Jin, Taoyong; Li, Dawei
2017-02-01
The accuracy and resolution of marine gravity field derived from satellite altimetry mainly depends on the range precision and dense spatial distribution. This paper aims at modeling a regional marine gravity field with improved accuracy and higher resolution (1‧ × 1‧) over Southeastern China Seas using additional data from CryoSat-2 as well as new data from AltiKa. Three approaches are used to enhance the precision level of satellite-derived gravity anomalies. Firstly we evaluate a suite of published retracking algorithms and find the two-step retracker is optimal for open ocean waveforms. Secondly, we evaluate the filtering and resampling procedure used to reduce the full 20 or 40 Hz data to a lower rate having lower noise. We adopt a uniform low-pass filter for all altimeter missions and resample at 5 Hz and then perform a second editing based on sea surface slope estimates from previous models. Thirdly, we selected WHU12 model to update the corrections provided in geophysical data record. We finally calculated the 1‧ × 1‧ marine gravity field model by using EGM2008 model as reference field during the remove/restore procedure. The root mean squares of the discrepancies between the new result and DTU10, DTU13, V23.1, EGM2008 are within the range of 1.8- 3.9 mGal, while the verification with respect to shipboard gravity data shows that the accuracy of the new result reached a comparable level with DTU13 and was slightly superior to V23.1, DTU10 and EGM2008 models. Moreover, the new result has a 2 mGal better accuracy over open seas than coastal areas with shallow water depth.
Seismic and gravity anomaly evidence of large-scale compressional deformation off SW Portugal
Cunha, T. A.; Watts, A. B.; Pinheiro, L. M.; Myklebust, R.
2010-04-01
Multi-channel seismic and gravity anomaly data have been used to determine the extent of compressional deformation along the SW Portugal rifted continental margin and place constraints on the long-term (> 1 M.a.) strength of the lithosphere. The seismic sections suggest that the region of compressional deformation is broad (˜ 100 km) and has been active since the Miocene. Integration with recently compiled high-resolution bathymetric data shows that the main thrust front is located along the base of the continental slope, between north of the Gorringe Bank and the Setúbal Canyon. Gravity data show that the thrust front is associated with a narrow isostatic anomaly 'high' of up to 70 mGal that is flanked on its NW edge by a broad 'low' of up to 20 mGal. This high-low 'couple' can be explained by compressional loading of extended continental lithosphere that increased its flexural strength (or equivalent elastic thickness, Te) since rifting. Based on combined 2-D backstripping and gravity modelling techniques we estimate a Te of ˜ 10 km during the main stretching episode, in the Late Jurassic (maybe earliest Cretaceous?), and of 35-50 km during the Miocene to Recent compression. The existence of a broad region of deformation off SW Portugal together with a strong lithosphere have implications for the rupture models of large earthquakes in the region, such as the 1755 Great Lisbon earthquake, particularly when accounting for a complex, multiple rupture in faults which cut through lithosphere of distinct nature and origin, as appears to be required by modellers to explain the historical observational data.
Paleocene-Eocene Thermal Maximum triggered by Volcanism revealed by Mercury anomalies
Khozyem, Hassan; Adatte, Thierry; Mbabi Bitchong, André; Chevalier, Yoann; Keller, Gerta
2017-04-01
The Paleocene-Eocene Thermal Maximum (PETM, 55.8±0.2 Ma) is marked by a global drop of 2-6‰ in 13C values and rapid warming of 4-5°C in tropical surface waters and 4-8°C in high latitudes. Climate warming persisted for several tens of thousands of years and resulted in rapid diversification in terrestrial mammals and marine planktic foraminifera. Deep-water bathyal benthic foraminifera suffered a mass extinction ( 40% species) but no significant extinctions occurred shallow shelf environments. Benthic extinctions are commonly explained as the effects of the initial stage of climate warming due to North Atlantic Volcanic Province volcanism (NAVP), which triggered methane release from ocean sediments causing global warming and ocean acidification. But the relationship between NAPV and the PETM events are not clearly demonstrated. Several studies [1-4] demonstrated the relationship between Hg anomalies in sediments and LIP activity associated with mass extinctions. We investigated the mercury (Hg) content of several sections located in deep bathyal (Zumaya, Trabakua, N-Spain) and outer shelf environments (Dababiya GSSP, Duwi, Egypt). At Zumaya the PETM is marked by a red clayey and marly interval poor in organic matter and coincident with a pronounced ∂13C negative shift. A comparable clay interval with low TOC content is also present in the Dababyia section in the lower part of the negative ∂13C shift, whereas the upper part of is enriched in TOC, reflecting increased productivity. A significant but unique Hg enrichment is observed at the onset of the PETM just below the carbone isotope shift in Spain as well as in Egypt. This increase, which is not correlated with clay or total organic carbon contents, suggests the Hg anomaly resulted from higher atmospheric Hg input into the marine realm, rather than organic matter scavenging and/or increased run-off. This Hg anomaly at the onset of the PETM provides the first direct evidence that volcanism played a
3D free-air gravity anomaly modeling for the Southeast Indian Ridge
Girolami, Chiara; Heyde, Ingo; Rinaldo Barchi, Massimiliano; Pauselli, Cristina
2016-04-01
In this study we analyzed the free-air gravity anomalies measured on the northwestern part of the Southeast Indian Ridge (hereafter SEIR) during the BGR cruise INDEX2012 with RV FUGRO GAUSS. The survey area covered the ridge from the Rodriguez Triple Junction along about 500 km towards the SSE direction. Gravity and magnetic data were measured along 65 profiles with a mean length of 60 km running approximately perpendicular to the ridge axis. The final gravity data were evaluated every 20 seconds along each profile. This results in a sampling interval of about 100 m. The mean spacing of the profiles is about 7 km. Together with the geophysical data also the bathymetry was measured along all profiles with a Kongsberg Simrad EM122 multibeam echosounder system. Previous studies reveal that the part of the ridge covered by the high resolution profiles is characterized by young geologic events (the oldest one dates back to 1 Ma) and that the SEIR is an intermediate spreading ridge. We extended the length of each profile to the area outside the ridge, integrating INDEX2012 high resolution gravity and bathymetric data with low resolution data derived from satellite radar altimeter measurements. The 3D forward gravity modeling made it possible to reconstruct a rough crustal density model for an extended area (about 250000 km2) of the SEIR. We analyzed the gravity signal along those 2D sections which cross particular geological features (uplifted areas, accommodation zones, hydrothermal fields and areas with hints for extensional processes e.g. OCCs) in order to establish a correlation between the gravity anomaly signal and the surface geology. We started with a simple "layer-cake" geologic model consisting of four density bodies which represent the sea, upper oceanic crust, lower oceanic crust and the upper mantle. Considering that in the study area the oceanic crust is young, we did not include the sediment layer. We assumed the density values of these bodies considering
Brown, Gareth; Ridley, Kevin; Rodgers, Anthony; de Villiers, Geoffrey
2016-10-01
Recent advances in the field of quantum technology offer the exciting possibility of gravimeters and gravity gradiometers capable of performing rapid surveys with unprecedented precision and accuracy. Measurements with sub nano-g (a billionth of the acceleration due to gravity) precision should enable the resolution of underground structures on metre length scales. However, deducing the exact dimensions of the structure producing the measured gravity anomaly is known to be an ill-posed inversion problem. Furthermore, the measurement process will be affected by multiple sources of uncertainty that increase the range of plausible solutions that fit the measured data. Bayesian inference is the natural framework for accommodating these uncertainties and providing a fully probabilistic assessment of possible structures producing inhomogeneities in the gravitational field. Previous work introduced the probability of excavation map as a means to convert the high-dimensional space belonging to the posterior distribution to an easily interpretable map. We now report on the development of the inference model to account for spatial correlations in the gravitational field induced by variations in soil density.
Eggers, G. L.; Lewis, K. W.; Simons, F. J.; Olhede, S.
2013-12-01
Venus does not possess a plate-tectonic system like that observed on Earth, and many surface features--such as tesserae and coronae--lack terrestrial equivalents. To understand Venus' tectonics is to understand its lithosphere, requiring a study of topography and gravity, and how they relate. Past studies of topography dealt with mapping and classification of visually observed features, and studies of gravity dealt with inverting the relation between topography and gravity anomalies to recover surface density and elastic thickness in either the space (correlation) or the spectral (admittance, coherence) domain. In the former case, geological features could be delineated but not classified quantitatively. In the latter case, rectangular or circular data windows were used, lacking geological definition. While the estimates of lithospheric strength on this basis were quantitative, they lacked robust error estimates. Here, we remapped the surface into 77 regions visually and qualitatively defined from a combination of Magellan topography, gravity, and radar images. We parameterize the spectral covariance of the observed topography, treating it as a Gaussian process assumed to be stationary over the mapped regions, using a three-parameter isotropic Matern model, and perform maximum-likelihood based inversions for the parameters. We discuss the parameter distribution across the Venusian surface and across terrain types such as coronoae, dorsae, tesserae, and their relation with mean elevation and latitudinal position. We find that the three-parameter model, while mathematically established and applicable to Venus topography, is overparameterized, and thus reduce the results to a two-parameter description of the peak spectral variance and the range-to-half-peak variance (in function of the wavenumber). With the reduction the clustering of geological region types in two-parameter space becomes promising. Finally, we perform inversions for the JOINT spectral variance of
HWANG; CheinWay
2010-01-01
The quality of satellite radar altimetric data is very important in studies of geodesy,geophysics,and oceanography.Over coastal oceans,altimeter waveforms are contaminated by the terrain and physical environments so that the accuracy of altimeter data is lower than that over open oceans.Here we develop a new multi-subwaveform parametric retracker(MSPR) to improve the quality of altimeter data for the recovery of gravity anomaly in coastal oceans.The least squares collocation method is used to recover the residual gravity anomaly over the coastal water from altimetric data.The waveform data records from Geosat/GM around Taiwan Island are practically retracked with MSPR.When compared with the Taiwan geoid height,the results retracked by MSPR are more accurate than those retracked by the well-known β-5-parmeter method and from the geophysical data records(GDRs).The gravity anomalies over Taiwan coastal waters are calculated from the retracked altimeter data with the least squares collocation.When we compared gravity anomalies computed using altimeter GDRs with the ship-borne gravity data over Taiwan coastal ocean,we found that the results from retracked data are more accurate than those from GDRs.
Gravity anomalies, flexure and mantle rheology seaward of circum-Pacific trenches
Hunter, J.; Watts, A. B.
2016-10-01
We have used ensemble averages of satellite-derived free-air gravity anomaly data, together with inverse modelling techniques, to determine the effective elastic thickness, Te, of circum-Pacific subducting oceanic lithosphere and its relationship to plate age. Synthetic modelling tests show that Te can be recovered best using gravity anomaly, rather than bathymetry, data and profiles that are at least 750 km long. Inverse modelling based on a uniform Te elastic plate suggests that Te increases with age of the subducting oceanic lithosphere and is given approximately by the depth to the 390 ± 10 °C oceanic isotherm based on a cooling plate model. Misfits between the observed and calculated gravity anomalies are significantly improved if a mechanically weak zone is included between the trench axis and the outer rise. This weak zone is coincident with observations of bend-faulting and seismicity. Inverse modelling shows that Te landward of the outer rise is generally 40-65 per cent less than the Te seaward of the outer rise. Both landward and seaward Te increases with age of the lithosphere and are given by the depth to the 342-349 °C and 671-714 °C oceanic isotherm, respectively. A dependence of Te on age is consistent with models for the cooling of oceanic lithosphere as it moves away from a mid-ocean ridge and the temperature-dependent ductile creep of oceanic lithospheric minerals such as olivine. By comparing the observed Te to the predicted Te based on laboratory-derived yield strength envelopes and an assumption of elastic-perfectly plastic deformation, we have attempted to constrain the rheology of oceanic lithosphere. Regardless of the assumed friction coefficient, the dry-olivine low-temperature plasticity flow laws of Goetze, Evans & Goetze, Raterron et al. and Mei et al. all provide quite a good fit to the observed Te at circum-Pacific subduction zones. This result contrasts with the Hawaiian Islands, where these flow laws are generally too strong to
Gravity anomalies, flexure and mantle rheology seaward of Circum-Pacific trenches
Hunter, J.; Watts, A. B.
2016-07-01
We have used ensemble averages of satellite-derived free-air gravity anomaly data, together with inverse modelling techniques, to determine the effective elastic thickness, Te, of circum-Pacific subducting oceanic lithosphere and its relationship to plate age. Synthetic modelling tests show that Te can be recovered best using gravity anomaly, rather than bathymetry, data and profiles that are at least 750 km long. Inverse modeling based on a uniform Te elastic plate suggests that Te increases with age of the subducting oceanic lithosphere and is given approximately by the depth to the 390 ± 10°C oceanic isotherm based on a cooling plate model. Misfits between the observed and calculated gravity anomalies are significantly improved if a mechanically weak zone is included between the trench axis and the outer rise. This weak zone is coincident with observations of bend-faulting and seismicity. Inverse modelling shows that Te landward of the outer rise is generally 40-65% less than the Te seaward of the outer rise. Both landward and seaward Te increases with age of the lithosphere and are given by the depth to the 342-349°C and 671-714°C oceanic isotherm respectively. A dependence of Te on age is consistent with models for the cooling of oceanic lithosphere as it moves away from a mid-ocean ridge and the temperature-dependent ductile creep of oceanic lithospheric minerals such as olivine. By comparing the observed Te to the predicted Te based on laboratory-derived yield strength envelopes and an assumption of elastic-perfectly plastic deformation, we have attempted to constrain the rheology of oceanic lithosphere. Regardless of the assumed friction coefficient, the dry-olivine low-temperature plasticity flow laws of Goetze (1978), Evans & Goetze (1979), Raterron et al. (2004) and Mei et al. (2010) all provide quite a good fit to the observed Te at circum-Pacific subduction zones. This result contrasts with the Hawaiian Islands, where these flow laws are generally
Cabrera, M.A. [Universidad Tecnologica Nacional, Tucuman (Argentina). CIASUR, Facultad Regional Tucuman; Universidad Nacional de Tucuman (Argentina). Lab. de Ionosfera; Pezzopane, M.; Zuccheretti, E. [Istituto Nazionale di Geofisica e Vulcanologia, Rome (Italy); Ezquer, R.G. [Universidad Tecnologica Nacional, Tucuman (Argentina). CIASUR, Facultad Regional Tucuman; Universidad Nacional de Tucuman (Argentina). Lab. de Ionosfera; Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires (Argentina)
2010-07-01
Range spread-F (RSF) and occurrence of ''satellite'' traces prior to RSF onset were studied at the southern peak of the ionospheric equatorial anomaly (EA). Ionograms recorded in September 2007 at the new ionospheric station of Tucuman, Argentina (26.9 S, 294.6 E, dip latitude 15.5 S), by the Advanced Ionospheric Sounder (AIS) developed at the Istituto Nazionale di Geofisica e Vulcanologia (INGV), were considered. Satellite traces (STs) are confirmed to be a necessary precursor to the appearance of an RSF trace on the ionograms. Moreover, an analysis of isoheight contours of electron density seems to suggest a relationship between RSF occurrence and gravity wave (GW) propagation. (orig.)
Holonomies, anomalies and the Fefferman-Graham ambiguity in AdS{sub 3} gravity
Rooman, M. E-mail: mrooman@ulb.ac.be; Spindel, Ph. E-mail: spindel@umh.ac.be
2001-01-29
Using the Chern-Simons formulation of (2+1)-gravity, we derive, for the general asymptotic metrics given by the Fefferman-Graham-Lee theorems, the emergence of the Liouville mode associated to the boundary degrees of freedom of (2+1)-dimensional anti-de-Sitter geometries. Holonomies are described through multi-valued gauge and Liouville fields and are found to algebraically couple the fields defined on the disconnected components of spatial infinity. In the case of flat boundary metrics, explicit expressions are obtained for the fields and holonomies. We also show the link between the variation under diffeomorphisms of the Einstein theory of gravitation and the Weyl anomaly of the conformal theory at infinity.
Modelling the gravity and magnetic field anomalies of the Chicxulub crater
Aleman, C. Ortiz; Pilkington, M.; Hildebrand, A. R.; Roest, W. R.; Grieve, R. A. F.; Keating, P.
1993-01-01
The approximately 180-km-diameter Chicxulub crater lies buried by approximately 1 km of sediment on the northwestern corner of the Yucatan Peninsula, Mexico. Geophysical, stratigraphic and petrologic evidence support an impact origin for the structure and biostratigraphy suggests that a K/T age is possible for the impact. The crater's location is in agreement with constraints derived from proximal K/T impact-wave and ejecta deposits and its melt-rock is similar in composition to the K/T tektites. Radiometric dating of the melt rock reveals an age identical to that of the K/T tektites. The impact which produced the Chicxulub crater probably produced the K/T extinctions and understanding the now-buried crater will provide constraints on the impact's lethal effects. The outstanding preservation of the crater, the availability of detailed gravity and magnetic data sets, and the two-component target of carbonate/evaporites overlying silicate basement allow application of geophysical modeling techniques to explore the crater under most favorable circumstances. We have found that the main features of the gravity and magnetic field anomalies may be produced by the crater lithologies.
Modelling the gravity and magnetic field anomalies of the Chicxulub crater
Aleman, C. Ortiz; Pilkington, M.; Hildebrand, A. R.; Roest, W. R.; Grieve, R. A. F.; Keating, P.
1993-01-01
The approximately 180-km-diameter Chicxulub crater lies buried by approximately 1 km of sediment on the northwestern corner of the Yucatan Peninsula, Mexico. Geophysical, stratigraphic and petrologic evidence support an impact origin for the structure and biostratigraphy suggests that a K/T age is possible for the impact. The crater's location is in agreement with constraints derived from proximal K/T impact-wave and ejecta deposits and its melt-rock is similar in composition to the K/T tektites. Radiometric dating of the melt rock reveals an age identical to that of the K/T tektites. The impact which produced the Chicxulub crater probably produced the K/T extinctions and understanding the now-buried crater will provide constraints on the impact's lethal effects. The outstanding preservation of the crater, the availability of detailed gravity and magnetic data sets, and the two-component target of carbonate/evaporites overlying silicate basement allow application of geophysical modeling techniques to explore the crater under most favorable circumstances. We have found that the main features of the gravity and magnetic field anomalies may be produced by the crater lithologies.
Agarwal, B. N. P.; Srivastava, Shalivahan
2010-07-01
In view of the several publications on the application of the Finite Element Method (FEM) to compute regional gravity anomaly involving only 8 nodes on the periphery of a rectangular map, we present an interactive FORTRAN program, FEAODD.FOR, for wider applicability of the technique. A brief description of the theory of FEM is presented for the sake of completeness. The efficacy of the program has been demonstrated by analyzing the gravity anomaly over Salt dome, South Houston, USA using two differently oriented rectangular blocks and over chromite deposits, Camaguey, Cuba. The analyses over two sets of data reveal that the outline of the ore body/structure matches well with the maxima of the residuals. Further, the data analyses over South Houston, USA, have revealed that though the broad regional trend remains the same for both the blocks, the magnitudes of the residual anomalies differ approximately by 25% of the magnitude as obtained from previous studies.
Sreejith, K.M.; Radhakrishna, M.; Krishna, K.S.; Majumdar, T.J.
The 85 degrees E Ridge is associated with two contrasting gravity anomalies: negative anomaly over the north part (up to 5 degrees N latitude), where the ridge structure is buried under thick Bengal Fan sediments and positive anomaly over the south...
Gabtni, H.; Jallouli, C.; Mickus, K. L.; Zouari, H.; Turki, M. M.
2006-03-01
Gravity and magnetic data were analyzed to add constraints on the location and nature of the Telemzan-Ghadames boundary (TGB) and structure of the Ghadames basin in southern Tunisia. TGB is the boundary between the thick sedimentary cover of the intracratonic Ghadames basin to the south and the thin sedimentary cover of the Saharan platform to the north. The upward continuation of the Bouguer gravity anomalies showed that the TGB is a regional geophysical feature that may have controlled the amount of sediment being deposited both north and south of the boundary and the tectonic environment in the region since Paleozoic time. To emphasize the shorter wavelength gravity and magnetic anomalies, a series of gray scale images of the directional horizontal gradients were constructed that determined a series of previously unknown east-west-trending gravity and magnetic anomalies south of 31.6°N that correspond to lineaments seen on a Landsat 7 image and the location of the TGB. Also, an edge-enhancement analysis illustrated the same linear gravity anomalies and showed the subbasins and uplifts within the Ghadames basin had source depths of between 0.5 and 3.4 km. A north-south trending gravity model showed that the TGB is a relatively gradual feature (possibly basement stepped down by relatively low-displacement faulting) controlling the subsidence of the main Ghadames basin and confirms the edge-enhancement analysis that subbasin S3 and uplift U1 are the main structural features within the Ghadames basin. The knowledge of basement architecture of the Ghadames basin is important for future petroleum exploration within this intracratonic basin.
A continuing discussion about the correlation of tidal gravity anomalies and heat flow densities
Melchior, P.
1995-04-01
to take into account the role of fluids (lubrication and stress corrosion owing to deep-seated saline waters or fluids) in crustal processes such as tidal deformations, such small tidal gravity anomalies cannot be correctly calculated. The use of a correlation technique therefore remains the only way to treat unexplained residues, even if this does not constitute an unequivocal proof. Other arguments have to be found to deny the existence of this correlation.
Agrawal, R.; Singh, S. K.; Rajawat, A. S.; Ajai
2014-11-01
Time-variable gravity changes are caused by a combination of postglacial rebound, redistribution of water and snow/ice on land and as well as in the ocean. The Gravity Recovery and Climate Experiment (GRACE) satellite mission, launched in 2002, provides monthly average of the spherical harmonic co-efficient. These spherical harmonic co-efficient describe earth's gravity field with a resolution of few hundred kilometers. Time-variability of gravity field represents the change in mass over regional level with accuracies in cm in terms of Water Equivalent Height (WEH). The WEH reflects the changes in the integrated vertically store water including snow cover, surface water, ground water and soil moisture at regional scale. GRACE data are also sensitive towards interior strain variation, surface uplift and surface subsidence cover over a large area. GRACE data was extracted over the three major Indian River basins, Indus, Ganga and Brahmaputra, in the Himalayas which are perennial source of fresh water throughout the year in Northern Indian Plain. Time series analysis of the GRACE data was carried out from 2003-2012 over the study area. Trends and amplitudes of the regional mass anomalies in the region were estimated using level 3 GRACE data product with a spatial resolution at 10 by 10 grid provided by Center for Space Research (CSR), University of Texas at Austin. Indus basin has shown a subtle decreasing trend from 2003-2012 however it was observed to be statistically insignificant at 95 % confidence level. Ganga and Brahmaputra basins have shown a clear decreasing trend in WEH which was also observed to be statistically significant. The trend analysis over Ganga and Brahamputra basins have shown an average annual change of -1.28 cm and -1.06 cm in terms of WEH whereas Indus basin has shown a slight annual change of -0.07 cm. This analysis will be helpful to understand the loss of mass in terms of WEH over Indian Himalayas and will be crucial for hydrological and
One-loop anomaly mediated scalar masses and (g - 2){sub μ} in pure gravity mediation
Evans, Jason L.; Olive, Keith A. [University of Minnesota, School of Physics and Astronomy, William I. Fine Theoretical Physics Institute, Minneapolis, MN (United States); Ibe, Masahiro [ICRR, University of Tokyo, Kashiwa (Japan); University of Tokyo, Kavli IPMU (WPI), TODIAS, Kashiwa (Japan); Yanagida, Tsutomu T. [University of Tokyo, Kavli IPMU (WPI), TODIAS, Kashiwa (Japan)
2014-02-15
We consider the effects of non-universalities among sfermion generations in models of PureGravity Mediation (PGM). In PGM models and in many models with strongly stabilized moduli, the gravitino mass may be O(100) TeV, whereas gaugino masses, generated through anomalies at one loop, remain relatively light O(1) TeV. In models with scalar mass universality, input scalar masses are generally very heavy (m{sub 0} ≅ m{sub 3/2}), resulting in a mass spectrum resembling that in split supersymmetry. However, if one adopts a no-scale or partial no-scale structure for theKahler manifold, sfermion masses may vanish at the tree level. It is usually assumed that the leading order anomaly mediated contribution to scalar masses appears at two loops. However, there are at least two possible sources for one-loop scalar masses. These may arise if Pauli.Villars fields are introduced as messengers of supersymmetry breaking. We consider the consequences of a spectrum in which the scalar masses associated with the third generation are heavy (order m{sub 3/2}) with one-loop scalar masses for the first two generations. A similar spectrum is expected to arise in GUT models based on E{sub 7}/SO(10) where the first two generations of scalars act as pseudo-Nambu-Goldstone bosons. Explicit breaking of this symmetry by the gauge couplings then generates one-loop masses for the first two generations. In particular, we show that it may be possible to reconcile the g{sub μ} - 2 discrepancy with potentially observable scalars and gauginos at the LHC. (orig.)
Bathymetry Prediction in Shallow Water by the Satellite Altimetry-Derived Gravity Anomalies
Kim, Kwang Bae; Yun, Hong Sik
2017-04-01
The satellite altimetry-derived free-air gravity anomalies (SAFAGAs) are correlated with undulations of crustal density variations under the seafloor. In this study, shipborne bathymetry from the Korea Rural Community Corporation (KRC) and the SAFAGAs from Scripps Institution of Oceanography were combined to predict bathymetry in shallow water. Density contrast of 5.0 g/cm3 estimated by the check points method of the gravity-geologic method (GGM) between seawater and the seafloor topographic mass was applied to predict bathymetry in shallow water areas outside of the Saemangeum Seawall located on the southwest coast of the Korean peninsula. Bathymetry predicted by the GGM was compared with depth measurements on the shipborne locations to analyze the bathymetry accuracy. The root mean square error (RMSE) of the differences of bathymetry between GGM and KRC on the KRC shipborne tracks in shallow water around the Saemangeum Seawall is 0.55 m. The topographic effects in off-tracks extracted from SAFAGAs in the GGM can be effectively utilized to predict bathymetry by combining with shipborne depth data in shallow water where shipborne depth data are limited. In addition, bathymetry and the SAFAGAs have a linear correlation in the 20 160 km wavelength. The coherency analysis was performed by computing the cross-spectral coherence between satellite altimetry derived bathymetry and the SAFAGAs. Acknowledgement This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2016R1A6A3A11931032).
Special relativity and theory of gravity via maximum symmetry and localization
2008-01-01
Like Euclid,Riemann and Lobachevski geometries are on an almost equal footing,based on the principle of relativity of maximum symmetry proposed by Professor Lu Qikeng and the postulate on invariant universal constants c and R,the de Sitter/anti-de Sitter（dS/AdS）special relativity on dS/AdS-space with radius R can be set up on an almost equal footing with Einstein’s special relativity on the Minkowski-space in the case of R→∞. Thus the dS-space is coin-like:a law of inertia in Beltrami atlas with Beltrami time simultaneity for the principle of relativity on one side,and the proper-time simultaneity and a Robertson-Walker-like dS-space with entropy and an accelerated expanding S3 fitting the cosmological principle on another side. If our universe is asymptotic to the Robertson-Walker-like dS-space of R（?）（3/Λ）1/2,it should be slightly closed in O（A）with entropy bound S（?）3πc3kB/ΛGh.Contrarily,via its asymptotic behavior, it can fix on Beltrami inertial frames without‘an argument in a circle’and acts as the origin of inertia. There is a triality of conformal extensions of three kinds of special relativity and their null physics on the projective boundary of a 5-d AdS-space,a null cone modulo projective equivalence[N]（?）p（AdS5）. Thus there should be a dS-space on the boundary of S5×AdS5 as a vacuum of supergravity. In the light of Einstein’s‘Galilean regions’,gravity should be based on the localized principle of relativity of full maximum symmetry with a gauge-like dynamics.Thus,this may lead to the theory of gravity of corresponding local symmetry.A simple model of dS-gravity characterized by a dimensionless constant g（?）（AGh/3c3）1/2～10-61shows the features on umbilical manifolds of local dS-invariance. Some gravitational effects out of general relativity may play a role as dark matter. The dark universe and its asymptotic behavior may already indicate that the dS special relativity and dS-gravity be the
Special relativity and theory of gravity via maximum symmetry and localization
GUO HanYing
2008-01-01
Like Euclid,Riemann and Lobachevski geometries are on an almost equal footing,based on the principle of relativity of maximum symmetry proposed by Professor Lu Qikeng and the postulate on invariant universal constants c and R,the de Sitter/anti-de Sitter (dS/AdS) special relativity on dS/AdS-space with radius R can be set up on an almost equal footing with Einstein's special relativity on the Minkowski-space in the case of R →∞.Thus the dS-space is coin-like: a law of inertia in Beltrami atlas with Beltrami time simultaneity for the principle of relativity on one side,and the proper-time simultaneity and a Robertson-Walker-like dS-space with entropy and an accelerated expanding S3 fitting the cosmological principle on another side.If our universe is asymptotic to the Robertson-Walker-like dS-space of R≈(3/∧)1/2,it should be slightly closed in O(A) with entropy bound S≈3πc3kB/∧Gh.Contrarily,via its asymptotic behavior,it can fix on Beltrami inertial frames without 'an argument in a circle' and acts as the origin of inertia.There is a triality of conformal extensions of three kinds of special relativity and their null physics on the projective boundary of a 5-d AdS-space,a null cone modulo projective equivalence [N]≈(e)p(AdS5).Thus there should be a dS-space on the boundary of S5 × AdS5 as a vacuum of supergravity.In the light of Einstein's 'Galilean regions',gravity should be based on the localized principle of relativity of full maximum symmetry with a gauge-like dynamics.Thus,this may lead to the theory of gravity of corresponding local symmetry.A simple model of dS-gravity characterized by a dimensionless constant g≈(∧Gh/3c3)1/2 ～ 10-61 shows the features on umbilical manifolds of local dS-invariance.Some gravitational effects out of general relativity may play a role as dark matter.The dark universe and its asymptotic behavior may already indicate that the dS special relativity and dS-gravity be the foundation of large scale physics.
Cowie, Leanne; Kusznir, Nick; Manatschal, Gianreto
2015-11-01
Knowledge and understanding of the ocean-continent transition (OCT) structure, continent-ocean boundary (COB) location and crustal type are of critical importance in evaluating rifted continental margin formation and evolution. OCT structure, COB location and magmatic type also have important implications for the understanding of the geodynamics of continental breakup and in the evaluation of petroleum systems in deep-water frontier oil and gas exploration at rifted continental margins. Mapping the distribution of thinned continental crust and lithosphere, its distal extent and the start of unequivocal oceanic crust and hence determining the OCT structure and COB location at rifted continental margins is therefore a generic global problem. In order to assist in the determination of the OCT structure and COB location, we present methodologies using gravity anomaly inversion, residual depth anomaly (RDA) analysis and subsidence analysis, which we apply to the west Iberian rifted continental margin. The west Iberian margin has one of the most complete data sets available for deep magma-poor rifted margins, so there is abundant data to which the results can be calibrated. Gravity anomaly inversion has been used to determine Moho depth, crustal basement thickness and continental lithosphere thinning; subsidence analysis has been used to determine the distribution of continental lithosphere thinning; and RDAs have been used to investigate the OCT bathymetric anomalies with respect to expected oceanic bathymetries at rifted continental margins. These quantitative analytical techniques have been applied to the west Iberian rifted continental margin along profiles IAM9, Lusigal 12 (with the TGS-extension) and ISE-01. Our predictions of OCT structure, COB location and magmatic type (i.e. the volume of magmatic addition, whether the margin is `normal' magmatic, magma-starved or magma-rich) have been tested and validated using ODP wells (Legs 103, 149 and 173), which provide
Sreejith, K. M.; Rajesh, S.; Majumdar, T. J.; Srinivasa Rao, G.; Radhakrishna, M.; Krishna, K. S.; Rajawat, A. S.
2013-01-01
Geoid data are more sensitive to density distributions deep within the Earth, thus the data are useful for studying the internal processes of the Earth leading to formation of geological structures. In this paper, we present much improved version of high resolution (1' × 1') geoid anomaly map of the northern Indian Ocean generated from the altimeter data obtained from Geodetic Missions of GEOSAT and ERS-1 along with ERS-2, TOPEX/POSIDEON and JASON satellites. The geoid map of the Indian Ocean is dominated by a significant low of -106 m south of Sri Lanka, named as the Indian Ocean Geoid Low (IOGL), whose origin is not clearly known yet. The residual geoid data are retrieved from the geoid data by removing the long-wavelength core-mantle density effects using recent spherical harmonic coefficients of Earth Gravity Model 2008 (EGM2008) up to degree and order 50 from the observed geoid data. The coefficients are smoothly rolled off between degrees 30-70 in order to avoid artifacts related to the sharp truncation at degree 50. With this process we observed significant improvement in the residual geoid data when compared to the previous low-spatial resolution maps. The previous version was superposed by systematic broad regional highs and lows (like checker board) with amplitude up to ±12 m, though the trends of geoid in general match in both versions. These methodical artifacts in the previous version may have arisen due to the use of old Rapp's geo-potential model coefficients, as well as sharp truncation of reference model at degree and order 50. Geoid anomalies are converted to free-air gravity anomalies and validated with cross-over corrected ship-borne gravity data of the Arabian Sea and Bay of Bengal. The present satellite derived gravity data matches well with the ship-borne data with Root Mean Square Error (RMSE) of 5.1-7.8 mGal, and this is found to be within the error limits when compared with other globally available satellite data. Spectral analysis of
K M Sreejith; M Radhakrishna; K S Krishna; T J Majumdar
2011-08-01
The 85°E Ridge extends from the Mahanadi Basin, off northeastern margin of India to the Afanasy Nikitin Seamount in the Central Indian Basin. The ridge is associated with two contrasting gravity anomalies: negative anomaly over the north part (up to 5°N latitude), where the ridge structure is buried under thick Bengal Fan sediments and positive anomaly over the south part, where the structure is intermittently exposed above the seafloor. Ship-borne gravity and seismic reflection data are modelled using process oriented method and this suggest that the 85°E Ridge was emplaced on approximately 10–15 km thick elastic plate (Te) and in an off-ridge tectonic setting. We simulated gravity anomalies for different crust-sediment structural configurations of the ridge that were existing at three geological ages, such as Late Cretaceous, Early Miocene and Present. The study shows that the gravity anomaly of the ridge in the north has changed through time from its inception to present. During the Late Cretaceous the ridge was associated with a significant positive anomaly with a compensation generated by a broad flexure of the Moho boundary. By Early Miocene the ridge was approximately covered by the postcollision sediments and led to alteration of the initial gravity anomaly to a small positive anomaly. At present, the ridge is buried by approximately 3 km thick Bengal Fan sediments on its crestal region and about 8 km thick pre- and post-collision sediments on the flanks. This geological setting had changed physical properties of the sediments and led to alter the minor positive gravity anomaly of Early Miocene to the distinct negative gravity anomaly.
Sreejith, K. M.; Radhakrishna, M.; Krishna, K. S.; Majumdar, T. J.
2011-08-01
The 85°E Ridge extends from the Mahanadi Basin, off northeastern margin of India to the Afanasy Nikitin Seamount in the Central Indian Basin. The ridge is associated with two contrasting gravity anomalies: negative anomaly over the north part (up to 5°N latitude), where the ridge structure is buried under thick Bengal Fan sediments and positive anomaly over the south part, where the structure is intermittently exposed above the seafloor. Ship-borne gravity and seismic reflection data are modelled using process oriented method and this suggest that the 85°E Ridge was emplaced on approximately 10-15 km thick elastic plate ( Te) and in an off-ridge tectonic setting. We simulated gravity anomalies for different crust-sediment structural configurations of the ridge that were existing at three geological ages, such as Late Cretaceous, Early Miocene and Present. The study shows that the gravity anomaly of the ridge in the north has changed through time from its inception to present. During the Late Cretaceous the ridge was associated with a significant positive anomaly with a compensation generated by a broad flexure of the Moho boundary. By Early Miocene the ridge was approximately covered by the post-collision sediments and led to alteration of the initial gravity anomaly to a small positive anomaly. At present, the ridge is buried by approximately 3 km thick Bengal Fan sediments on its crestal region and about 8 km thick pre- and post-collision sediments on the flanks. This geological setting had changed physical properties of the sediments and led to alter the minor positive gravity anomaly of Early Miocene to the distinct negative gravity anomaly.
1982-03-01
mean gravity anomaly. To do this, it is necessary to apply a data averaging integral of the form ( Heiskanen and Moritz, 1967): -- I a b Ag f b Ag(x,y...Rapp for practical applica- tion on digital computers. Details can be found in Heiskanen and Moritz (1967), and Rapp (1964). Although least squares...methods: Institute for Physicalische Geodasie, Technische Hochschule, Darmstadt, Federal Republic of Germany. Heiskanen , W., and Moritz, H., 1967, Physical
SU-E-T-444: Gravity Effect On Maximum Leaf Speed in Dynamic IMRT Treatments
Olasolo, J; Pellejero, S; Gracia, M; Gallardo, N; Martin, ML; Lozares, S; Maneru, F; Bragado, L; Miquelez, S [Complejo Hospitalario de Navarra, Pamplona (Spain); Artacho, JM [Universidad de Zaragoza, Zaragoza (Spain)
2015-06-15
Purpose: A leaf sequencing algorithm has been recently developed in our department. Our purpose is to utilize this algorithm to reduce treatment time by studying the feasibility of using several maximum leaf speeds depending on gantry angle and leaf thickness (0.5 or 1 cm at isocenter). To do so, the gravity effect on MLC performance has been examined by means of analysing the dynalog files. Methods: Leaf position errors has been ascertained according to gantry angle and leaf speed in MLC Millenium120 (Varian). In order to do this, the following test has been designed: all leaves move in synchrony, with same speed and 1 cm gap between opposite leaves. This test is implemented for 18 different speeds: 0.25-0.5-0.75-1-1.25-1.5-1.75-2-2.1-2.2-2.3-2.4-2.5-2.6-2.7-2.8-2.9-3.0 cm/s and 8 gantry angles: 0-45-90-135-180-225-270-315. Collimator angle is 2 degrees in all cases since it is the most usual one in IMRT treatments in our department. Dynamic tolerance is 2 mm. Dynalogs files of 10 repetitions of the test are analysed with a Mathlab in-house developed software and RMS error and 95th percentiles are calculated. Varian recommends 2.5 cm/s as the maximum leaf speed for its segmentation algorithm. In our case, we accept this speed in the most restrictive situation: gantry angle 270 and 1 cm leaf thickness. Maximum speeds for the rest of the cases are calculated by keeping the difference between 95th percentile and dynamic tolerance. In this way, beam hold-off probability does not increase. Results: Maximum speeds every 45 degrees of gantry rotation have been calculated for both leaf thickness. These results are 2.9-2.9-2.9-2.9-2.7-2.6-2.6-2.7 cm/s for 0.5 cm leaf thickness and 2.7-2.7-2.7-2.7-2.6-2.5-2.5-2.6 cm/s for 1 cm leaf thickness. Conclusion: Gravity effect on MLC positioning has been studied. Maximum leaf speed according to leaf thickness and gantry angle have been calculated which reduces treatment time.
Sawada, Natsuki; Morota, Tomokatsu; Kato, Shinsuke; Ishihara, Yoshiaki; Hiramatsu, Yoshihiro
2016-05-01
Gravity data obtained from the Gravity Recovery and Interior Laboratory have revealed linear gravity anomalies (LGAs) formed by the early global expansion of the Moon and subsequent magma intrusion. In this study, using Lunar Orbiter Laser Altimeter topographic data, we investigated topographic profiles across LGAs to verify that they were formed by extensional tectonics. We found that 17 of the 20 LGAs investigated exhibited a valley structure, suggesting that they were formed by tensile stress. Assuming that these topographic depressions accompanied graben formation, the increase in the lunar radius is estimated to be on the order of several tens of meters. On the other hand, assuming that these topographic depressions accompanied flexure of elastic lithosphere due to the LGA load, the elastic thickness during the LGA formation is estimated as ~10 km. The crater frequencies in the vicinity of LGAs indicate that the peak tectonic activity occurred before the basin-forming epoch.
Achour, Jibril Ben; Marciano, Antonino
2016-01-01
Using self dual Ashtekar variables, we investigate (at the effective level) the spherically symmetry reduced model of loop quantum gravity, both in vacuum and when coupled to a scalar field. Within the real Ashtekar-Barbero formulation, the system scalar field coupled to spherically symmetric gravity is known to possess a non closed (quantum) algebra of constraints once the holonomy corrections are introduced, which forbids the loop quantization of the model. Moreover, the vacuum case, while not anomalous, introduces modifications which are usually interpreted as a signature change of the metric in the deep quantum region. We show in this paper that both those difficulties disappear when working with self dual Ashtekar variables, both in the vacuum case and in the case of gravity minimally coupled to a scalar field. In this framework, the algebra of the holonomy corrected constraints is anomaly free and reproduces the classical hypersurface deformation algebra without any deformations. A possible path towards...
Xuezhong Yu
2017-01-01
Full Text Available The widely distributed E–W-trending magnetic anomaly stripes in the central basin and the N–E-trending magnetic anomaly stripes in the southwest sub-basin provide the most important evidence for Neogene expansion of the South China Sea. The expansion mechanism remains, however, controversial because of the lack of direct drilling data, non-systematic marine magnetic survey data, and irregular magnetic anomaly stripes with two obvious directions. For example, researchers have inferred different ages and episodes of expansion for the central basin and southwest sub-basin. Major controversy centers on the order of basinal expansion and the mechanism of expansion for the entire South China Sea basin. This study attempts to constrain these problems from a comprehensive analysis of the seafloor topography, magnetic anomaly stripes, regional aeromagnetic data, satellite gravity, and submarine geothermics. The mapped seafloor terrain shows that the central basin is a north-south rectangle that is relatively shallow with many seamounts, whereas the southwest sub-basin is wide in northeast, gradually narrows to the southwest, and is relatively deeper with fewer seamounts. Many magnetic anomaly stripes are present in the central basin with variable dimensions and directions that are dominantly EW-trending, followed by the NE-, NW- and NS-trending. Conversely such stripes are few in the southwest sub-basin and mainly NE-trending. Regional magnetic data suggest that the NW-trending Ailaoshan-Red River fault extends into the South China Sea, links with the central fault zone in the South China Sea, which extends further southward to Reed Tablemount. Satellite gravity data show that both the central basin and southwest sub-basin are composed of oceanic crust. The Changlong seamount is particularly visible in the southwest sub-basin and extends eastward to the Zhenbei seamount. Also a low gravity anomaly zone coincides with the central fault zone in the sub
Javier Sanchez-Rojas
2012-01-01
Full Text Available A new gravity data compilation for Venezuela was processed and homogenized. Gravity was measured in reference to the International Gravity Standardization Net 1971, and the complete Bouguer anomaly was calculated by using the Geodetic Reference System 1980 and 2.67 Mg/m3. A regional gravity map was computed by removing wavelengths higher than 200 km from the Bouguer anomaly. After the anomaly separation, regional and residual Bouguer gravity fields were then critically discussed in term of the regional tectonic features. Results were compared with the previous geological and tectonic information obtained from former studies. Gravity and topography data in the spectral domain were used to examine the elastic thickness and depths of the structures of the causative measured anomaly. According to the power spectrum analysis results of the gravity data, the averaged Moho depths for the massif, plains, and mountainous areas in Venezuela are 42, 35, and 40 km, respectively. The averaged admittance function computed from the topography and Free-Air anomaly profiles across Mérida Andes showed a good fit for a regional compensation model with an effective elastic thickness of 15 km.
She, Yawen; Fu, Guangyu; Wang, Zhuohua; Liu, Tai; Xu, Changyi; Jin, Honglin
2016-10-01
The current work describes the combined data of three field campaigns, spanning 2009-2013. Their joint gravity and GPS observations thoroughly cover the sites of lithospheric flexure between the Sichuan Basin and the Eastern Tibetan Plateau. The study area's free-air gravity anomalies (FGAs) are updated by using a remove-and-restore algorithm which merges EGM2008 data with in situ observations. These new FGAs show pairs of positive and negative anomalies along the eastern edges of the Tibetan Plateau. The FGAs are used to calculate effective elastic thickness ( T e) and load ratios ( F) of the lithosphere. Admittance analysis indicates the T e of Longmen Shan (LMS) to be 6 km, and profile analysis indicates that the T e of the Sichuan Basin excesses 30 km. The load ratio ( F 1 = 1) confirms that the lithospheric flexure of the LMS area can be attributed solely to the surface load of the crust. [Figure not available: see fulltext. Caption: The current work describes the combined data of three field campaigns, spanning 2009-2013. Their joint gravity and GPS observations thoroughly cover the sites of lithospheric flexure between the Sichuan Basin and the Eastern Tibetan Plateau. The study area's free-air gravity anomalies (FGAs) are updated by using a remove-and-restore algorithm which merges EGM2008 data with in situ observations. With the new FGAs data, the lithospheric strength of the study area is studied by the authors, and they also give a combined model to illustrate the uplift mechanism of this area.
Scherwath, Martin; Stern, Tim; Davey, Fred; Davies, Rob
2006-11-01
Isostatic considerations exhibit differences between the northern, central and southern parts of the Pacific-Australian plate collision in South Island, New Zealand. In the northern part mean elevations are moderate and the gravity low is small; the central part contains the highest elevations, and gravity and elevations correspond to each other relatively well; and in the southern part the gravity low is strongest whereas the mean elevations are moderate again. These differences indicate changes in the character of the isostatic compensation and are explained by increased thickening and widening of the crustal root from north to south, and also by the long wavelength gravity response to a mantle density anomaly that increases towards the south. A simple 3-D gravity model is derived that includes the detailed crustal structures from the South Island GeopHysical Transect (SIGHT) experiment as well as a high-density anomaly in the mantle inferred from teleseismic data. The model indicates that cold and, therefore, dense upper mantle material penetrates the asthenosphere to a greater extent in the south, similar to the behaviour of an apparently highly ductile lower crust. As plate reconstruction suggests more lithospheric shortening in the north, our model corresponds to lithospheric material escaping laterally to the south, almost perpendicular to the compression caused by lithospheric shortening of the mantle. Therefore, in addition to the prevailing mantle shear in New Zealand, there may also be a component of extrusional mantle creep beneath the Southern Alps orogen, which could have caused some of the observed large seismic anisotropy in this region. We may have also found evidence for submerged Eocene-Miocene oceanic lithosphere beneath the southeastern part of South Island that has been unaccounted for after plate reconstruction.
Ekinci, Yunus Levent; Balkaya, Çağlayan; Göktürkler, Gökhan; Turan, Seçil
2016-06-01
An efficient approach to estimate model parameters from residual gravity data based on differential evolution (DE), a stochastic vector-based metaheuristic algorithm, has been presented. We have showed the applicability and effectiveness of this algorithm on both synthetic and field anomalies. According to our knowledge, this is a first attempt of applying DE for the parameter estimations of residual gravity anomalies due to isolated causative sources embedded in the subsurface. The model parameters dealt with here are the amplitude coefficient (A), the depth and exact origin of causative source (zo and xo, respectively) and the shape factors (q and ƞ). The error energy maps generated for some parameter pairs have successfully revealed the nature of the parameter estimation problem under consideration. Noise-free and noisy synthetic single gravity anomalies have been evaluated with success via DE/best/1/bin, which is a widely used strategy in DE. Additionally some complicated gravity anomalies caused by multiple source bodies have been considered, and the results obtained have showed the efficiency of the algorithm. Then using the strategy applied in synthetic examples some field anomalies observed for various mineral explorations such as a chromite deposit (Camaguey district, Cuba), a manganese deposit (Nagpur, India) and a base metal sulphide deposit (Quebec, Canada) have been considered to estimate the model parameters of the ore bodies. Applications have exhibited that the obtained results such as the depths and shapes of the ore bodies are quite consistent with those published in the literature. Uncertainty in the solutions obtained from DE algorithm has been also investigated by Metropolis-Hastings (M-H) sampling algorithm based on simulated annealing without cooling schedule. Based on the resulting histogram reconstructions of both synthetic and field data examples the algorithm has provided reliable parameter estimations being within the sampling limits of
Rummel, R.; Sjoeberg, L.; Rapp, R. H.
1978-01-01
A numerical method for the determination of gravity anomalies from geoid heights is described using the inverse Stokes formula. This discrete form of the inverse Stokes formula applies a numerical integration over the azimuth and an integration over a cubic interpolatory spline function which approximates the step function obtained from the numerical integration. The main disadvantage of the procedure is the lack of a reliable error measure. The method was applied on geoid heights derived from GEOS-3 altimeter measurements in the calibration area of the GEOS-3 satellite.
Ryu, K.; Oyama, K. I.; Sun, Y. Y.; Liu, T. J. Y.
2016-12-01
Some examples of the equatorial plasma density measured by DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) increased before some large earthquakes are introduced. Previous examples of the pre-seismic equatorial ionization anomalies (EIA) associated with the northern Sumatra earthquake of 2005, Wenchuan earthquake of 2008, Pisco earthquake of 2007, and Kuril Island earthquake of 2007, commonly accompanied conspicuous precursory EIA enhancements distinct from the longitudinal asymmetric variation which is known as a result of ionospheric interaction with the thermospheric tidal modulation generating wave structure in the global ionospheric density profile in the dayside local time. The physical mechanisms of the seismo-ionospheric coupling manifested as the enhanced EIA intensity can be ascribed either to the gravity wave or static electric field generated by the lithosphere-atmosphere-ionosphere coupling, which is still in debate because of lack in confident observational evidences. Molucca sea earthquake of 2007 which accompanied dominant-ever precursory EIA enhancement was selected as a case study to investigate whether the seismo-ionospheric coupling was originated from the gravity wave propagating from the mesosphere to the thermosphere using the SABER satellite data. The gravity wave intensity according to the frequency was derived by applying the s-transform to the atmospheric neutral temperature profile measured by SABER limb-scanning method. The initial analysis results of the ionospheric plasma condition and thermospheric gravity wave derived from DEMETER, CHAMP, and SABER are introduced and the possible association between the physical conditions are discussed.
Blakely, Richard J.; Sherrod, Brian L.; Weaver, Craig S.; Wells, Ray E.; Rohay, Alan C.
2014-06-01
The Yakima fold and thrust belt (YFTB) in central Washington has accommodated regional, mostly north-directed, deformation of the Cascadia backarc since prior to emplacement of Miocene flood basalt of the Columbia River Basalt Group (CRBG). The YFTB consists of two structural domains. Northern folds of the YFTB strike eastward and terminate at the western margin of a 20-mGal negative gravity anomaly, the Pasco gravity low, straddling the North American continental margin. Southern folds of the YFTB strike southeastward, form part of the Olympic-Wallowa lineament (OWL), and pass south of the Pasco gravity low as the Wallula fault zone. An upper crustal model based on gravity and magnetic anomalies suggests that the Pasco gravity low is caused in part by an 8-km-deep Tertiary basin, the Pasco sub-basin, abutting the continental margin and concealed beneath CRBG. The Pasco sub-basin is crossed by north-northwest-striking magnetic anomalies caused by dikes of the 8.5 Ma Ice Harbor Member of the CRBG. At their northern end, dikes connect with the eastern terminus of the Saddle Mountains thrust of the YFTB. At their southern end, dikes are disrupted by the Wallula fault zone. The episode of NE-SW extension that promoted Ice Harbor dike injection apparently involved strike-slip displacement on the Saddle Mountains and Wallula faults. The amount of lateral shear on the OWL impacts the level of seismic hazard in the Cascadia region. Ice Harbor dikes, as mapped with aeromagnetic data, are dextrally offset by the Wallula fault zone a total of 6.9 km. Assuming that dike offsets are tectonic in origin, the Wallula fault zone has experienced an average dextral shear of 0.8 mm/y since dike emplacement 8.5 Ma, consistent with right-lateral stream offsets observed at other locations along the OWL. Southeastward, the Wallula fault transfers strain to the north-striking Hite fault, the possible location of the M 5.7 Milton-Freewater earthquake in 1936.
Plouff, Donald
1992-01-01
These gravity maps are part of a folio of maps of the Tonopah 1 degree by 2 degrees quadrangle, Nevada, prepared under the Conterminous United States Mineral Assessment Program. Each product of the folio is designated by a different letter symbol, starting with A, in the MF-1877 folio. The quadrangle encompasses an area of about 19,500 km2 in the west central part of Nevada.
Au, Andrew Y.; Brown, Richard D.; Welker, Jean E.
1991-01-01
Satellite-based altimetric data taken by GOES-3, SEASAT, and GEOSAT over the Aral Sea, the Black Sea, and the Caspian Sea are analyzed and a least squares collocation technique is used to predict the geoid undulations on a 0.25x0.25 deg. grid and to transform these geoid undulations to free air gravity anomalies. Rapp's 180x180 geopotential model is used as the reference surface for the collocation procedure. The result of geoid to gravity transformation is, however, sensitive to the information content of the reference geopotential model used. For example, considerable detailed surface gravity data were incorporated into the reference model over the Black Sea, resulting in a reference model with significant information content at short wavelengths. Thus, estimation of short wavelength gravity anomalies from gridded geoid heights is generally reliable over regions such as the Black Sea, using the conventional collocation technique with local empirical covariance functions. Over regions such as the Caspian Sea, where detailed surface data are generally not incorporated into the reference model, unconventional techniques are needed to obtain reliable gravity anomalies. Based on the predicted gravity anomalies over these inland seas, speculative tectonic structures are identified and geophysical processes are inferred.
Eggers, G. L.; Lewis, K. W.; Simons, F. J.
2012-12-01
Venus has undergone a markedly different evolution than Earth. Its tectonics do not resemble the plate-tectonic system observed on Earth, and many surface features—such as tesserae and coronae—lack terrestrial equivalents. To understand Venus' tectonics is to understand its lithosphere. Lithospheric parameters such as the effective elastic thickness have previously been estimated from the correlation between topography and gravity anomalies, either in the space domain or the spectral domain (where admittance or coherence functions are estimated). Correlation and spectral analyses that have been obtained on Venus have been limited by geometry (typically, only rectangular or circular data windows were used), and most have lacked robust error estimates. There are two levels of error: the first being how well the correlation, admittance or coherence can be estimated; the second and most important, how well the lithospheric elastic thickness can be estimated from those. The first type of error is well understood, via classical analyses of resolution, bias and variance in multivariate spectral analysis. Understanding this error leads to constructive approaches of performing the spectral analysis, via multi-taper methods (which reduce variance) with well-chosen optimal tapers (to reduce bias). The second type of error requires a complete analysis of the coupled system of differential equations that describes how certain inputs (the unobservable initial loading by topography at various interfaces) are being mapped to the output (final, measurable topography and gravity anomalies). The equations of flexure have one unknown: the flexural rigidity or effective elastic thickness—the parameter of interest. Fortunately, we have recently come to a full understanding of this second type of error, and derived a maximum-likelihood estimation (MLE) method that results in unbiased and minimum-variance estimates of the flexural rigidity under a variety of initial
无
2009-01-01
In this study,the terrain correction for lunar free-air gravity anomaly (FAGA) is calculated in spherical coordinates based on the global topography data detected by the laser altimeter on Chang’E-1 (CE-1). The obtained lunar Bouguer gravity anomaly (BGA) reveals density irregularities of the interior mass. BGA is important in characterizing the mascon basins. According to the BGA of the Moon,the South Pole-Aitken (SPA) basin is considered the largest mascon basin on the Moon,and the feature of BGA in the basin implies the impacting direction. Further,the mascon basins seem to be classified into two types,Type Highland and Type Plain. For the mascon basins of Type Highland the dense materials mainly come from the shallow crust,which are associated with the basalt deposits. The other type,Type Plain,includes mascon basins whose major dense materials may be located deep at the litho-sphere,corresponding to the uplifted mantle.
Sheena V Dev; M Radhakrishna; Shyam Chand; C Subrahmanyam
2012-06-01
Litho-stratigraphic variation of sedimentary units constructed from seismic sections and gravity anomaly in the Konkan and Kerala basins of the western continental margin of India (WCMI) have been used to model processes such as lithospheric rifting mechanism, its strength, and evolution of flank uplift topography that led to the present-day Western Ghats escarpment. Based on the process-oriented approach, two lithospheric models (necking and magmatic underplating) of evolution of the margin were tested. Both, necking and underplating models suggest an effective elastic thickness (Te) of 5 km and 10 km along Konkan and Kerala basins, respectively and a deep level of necking at 20 km at both basins. Model study suggests that the necking model better explains the observed gravity anomalies in the southern part of the WCMI. A synthesis of these results along with the previously published elastic thickness estimates along the WCMI suggests that a low-to-intermediate strength lithosphere and a deeper level of necking explains the observed flank-uplift opography of the Western Ghats. Process-oriented gravity modeling further suggests that the lateral variations in the lithospheric strength, though not very significant, exist from north to south within a distance of 600 km in the Konkan and Kerala basins along the WCMI at the time of rifting. A comparison with previous Te estimates from coherence analysis along the WCMI indicates that the lithospheric strength did not change appreciably since the time of rifting and it is low both onshore and offshore having a range of 5–15 km.
Far-zone contributions of airborne gravity anomalies' upward/downward continuation
Boyang Zhou
2016-11-01
Full Text Available Airborne gravimetry has become a vital technique in local gravity field approximation, and upward/downward continuation of gravity data is a key process of airborne gravimetry. In these procedures, the integral domain is divided into two parts, namely the near-zone and the far-zone. The far-zone contributions are approximated by the truncation coefficients and a global geo-potential model, and their values are controlled by several issues. This paper investigates the effects of flight height, the size of near-zone cap, and Remove-Compute-Restore (RCR technique upon far-zone contributions. Results show that at mountainous area the far-zone contributions can be ignored when EIGEN-6C of 360 degree is removed from the gravity data, together with a near-zone cap of 1° and a flight height less than 10 km, while at flat area EIGEN-6C of 180 degree is feasible.
Rao, M.M.M.; Murty, T.V.R.; Murthy, K.S.R.; Vasudeva, R.Y.
have been carried out in the present work to estimate accurate model parameters by inverting the observed anomaly using GI approach via SVD. While solving the inverse problem, data kernel has been generated through the model. Using this data kernel, SVD...
G. O. Walker
Full Text Available Median hourly, electron content-latitude profiles obtained in South East Asia under solar minimum and maximum conditions have been used to establish seasonal and solar differences in the diurnal variations of the ionospheric equatorial anomaly (EIA. The seasonal changes have been mainly accounted for from a consideration of the daytime meridional wind, affecting the EIA diffusion of ionization from the magnetic equator down the magnetic field lines towards the crests. Depending upon the seasonal location of the subsolar point in relation to the magnetic equator diffusion rates were increased or decreased. This led to crest asymmetries at the solstices with (1 the winter crest enhanced in the morning (increased diffusion rate and (2 the same crest decaying most rapidly in the late afternoon (faster recombination rate at lower ionospheric levels. Such asymmetries were also observed, to a lesser extent, at the equinoxes since the magnetic equator (located at about 9°N lat does not coincide with the geographic equator. Another factor affecting the magnitude of a particular electron content crest was the proximity of the subsolar point, since this increased the local ionization production rate. Enhancements of the EIA took place around sunset, mainly during the equinoxes and more frequently at solar maximum, and also there was evidence of apparent EIA crest resurgences around 0300 LST for all seasons at solar maximum. The latter are thought to be associated with the commonly observed, post-midnight, ionization enhancements at midlatitudes, ionization being transported to low latitudes by an equatorward wind. The ratio increases in crest peak electron contents from solar minimum to maximum of 2.7 at the equinoxes, 2.0 at the northern summer solstice and 1.7 at northern winter solstice can be explained, only partly, by increases in the magnitude of the eastward electric field E overhead the magnetic equator affecting the [
Hududillah, Teuku Hafid; Simanjuntak, Andrean V. H.; Husni, Muhammad
2017-07-01
Gravity is a non-destructive geophysical technique that has numerous application in engineering and environmental field like locating a fault zone. The purpose of this study is to spot the Seulimeum fault system in Iejue, Aceh Besar (Indonesia) by using a gravity technique and correlate the result with geologic map and conjointly to grasp a trend pattern of fault system. An estimation of subsurface geological structure of Seulimeum fault has been done by using gravity field anomaly data. Gravity anomaly data which used in this study is from Topex that is processed up to Free Air Correction. The step in the Next data processing is applying Bouger correction and Terrin Correction to obtain complete Bouger anomaly that is topographically dependent. Subsurface modeling is done using the Gav2DC for windows software. The result showed a low residual gravity value at a north half compared to south a part of study space that indicated a pattern of fault zone. Gravity residual was successfully correlate with the geologic map that show the existence of the Seulimeum fault in this study space. The study of earthquake records can be used for differentiating the active and non active fault elements, this gives an indication that the delineated fault elements are active.
Griscom, A.; Jachens, R.C.
1989-01-01
Geologic and geophysical data for the San Andreas fault system north of San Francisco suggest that the eastern boundary of the Pacific plate migrated eastward from its presumed original position at the base of the continental slope to its present position along the San Andreas transform fault by means of a series of eastward jumps of the Mendocino triple junction. These eastward jumps total a distance of about 150 km since 29 Ma. Correlation of right-laterally displaced gravity and magnetic anomalies that now have components at San Francisco and on the shelf north of Point Arena indicates that the presently active strand of the San Andreas fault north of the San Francisco peninsula formed recently at about 5 Ma when the triple junction jumped eastward a minimum of 100 km to its present location at the north end of the San Andreas fault. -from Authors
Gorringe Ridge gravity and magnetic anomalies are compatible with thrusting at a crustal scale
Galindo-Zaldívar, J.; Maldonado, A.; Schreider, A. A.
2003-06-01
The main features of the deep structure of the Gorringe Ridge are analysed on the basis of gravity and magnetic measurements, as well as seismic profiles, drill holes, rock dredges, submersible observations and seismicity data. The gravity and magnetic models of the Gettysburg and Ormonde seamounts, which form the Gorringe Ridge, suggest that the Moho is approximately flat and the upper part of the ridge corresponds to a northwestwards vergent fold. This structure is the result of a northwestward vergent thrust that deformed the oceanic crust, with a minimum slip of approximately 20 km. The activity of the thrust probably started 20 Myr, and produced the recent stages of seamount uplift. The seamount is mainly composed of gabbros of the oceanic crust, serpentinized rocks and alkaline basalts. The large antiform, located in the hangingwall of the thrust, is probably deformed by minor faults. This oceanic ridge is a consequence of the oblique convergence between the African Plate and the overlapping Eurasian Plate.
Wada, Shigeki; Sawada, Akihiro; Hiramatsu, Yoshihiro; Matsumoto, Nayuta; Okada, Shinsuke; Tanaka, Toshiyuki; Honda, Ryo
2017-01-01
We have investigated gravity anomalies around the Niigata plain, which is a sedimentary basin in central Japan bounded by mountains, to examine the continuity of subsurface fault structures of a large fault zone—the eastern boundary fault zone of the Niigata plain (EBFZNP). The features of the Bouguer anomaly and its first horizontal and vertical derivatives clearly illustrate the EBFZNP. The steep first horizontal derivative and the zero isoline of the vertical derivative are clearly recognized along the entire EBFZNP over an area that shows no surface topographic features of an active fault. Two-dimensional density structure analyses also confirm a relationship between the two first derivatives and the subsurface fault structure. Therefore, we conclude that the length of the EBFZNP as an active fault extends to 56 km, which is longer than previously estimated. This length leads to an estimation of a moment magnitude of 7.4 of an expected earthquake from the EBFZNP.[Figure not available: see fulltext.
Herceg, Matija; Artemieva, Irina; Thybo, Hans
2013-01-01
We investigate the effect of the crustal structure heterogeneity and uncertainty in its determination on stripped gravity field. The analysis is based on interpretation of residual upper mantle gravity anomalies which are calculated by subtracting (stripping) the gravitational effect of the crust...... a relatively small range of expected density variations in the lithospheric mantle, knowledge on the uncertainties associated with incomplete knowledge of density structure of the crust is of utmost importance for further progress in such studies......) uncertainties in the velocity-density conversion and (ii) uncertainties in knowledge of the crustal structure (thickness and average Vp velocities of individual crustal layers, including the sedimentary cover). In this study, we address both sources of possible uncertainties by applying different conversions...... from velocity to density and by introducing variations into the crustal structure which corresponds to the uncertainty of its resolution by high-quality and low-quality seismic models. We examine the propagation of these uncertainties into determinations of lithospheric mantle density. The residual...
Disturbance Vector in Space from Surface Gravity Anomalies Using Complementary Models.
1985-08-01
sphere. For the dense 5’x5" data used in our New Mexico tests, however, the Dirac results were superior to those of the l.s.c. because of the ill...Lelgemann, D., "Spherical Approximation and the Combination of Gravimetric and Satellite Data," Bolletino di Geodesia e Scienze Affini, vol. 32, No. 4... Geodesia e Scienze Affini, vol. 41, No. 1, pp. 89-103, 1982. Rapp, R.H., "A FORTRAN Program for the Computation of the Normal Gravity and Gravitational
Maximum holding endurance time: Effects of load and load's center of gravity height.
Lee, Tzu-Hsien
2015-01-01
Manual holding task is a potential risk to the development of musculoskeletal injuries since it is prone to induce localized muscle fatigue. Maximum holding endurance time is a significant parameter for the design of manual holding task. This study aimed to examine the effects of load and load's COG height on maximum holding endurance time. Fifteen young and healthy males were recruited as participants. A factorial design was used to examine the effects of load and load's COG height on maximum holding endurance time. Four levels of load (15% , 30% , 45% and 60% of the participant's maximum holding capacity) and two levels of load's COG height in box (0 cm and 40 cm high from the handle position) were examined. Maximum holding endurance time decreased with increasing load and/or increasing load's COG height. The effect of load's COG height on maximum holding endurance time decreased with increasing load. Load, load's COG height, and the interaction of load and load's COG height significantly affected maximum holding endurance time. Practitioners should realize the effects of load, load's COG height, and the interaction of load and load's COG height on maximum holding endurance time when setting the working conditions of holding tasks.
B. B. Zhao
2011-02-01
Full Text Available A singular value decomposition (SVD program on MATLAB platform was effectively used to handle gravity signals for the Tongshi gold field. Firstly, the gravity signals were decomposed into different eigenimages with the help of singular value decomposition method (SVD. Secondly, the thresholds between the eigenvalues reflecting different layers of ore-controlling factors were established by multi-fractal method. Finally images reflecting different layers of ore-controlling factors were rebuilt. This yielded two layers of two-dimensional singular value images that depict regional and local ore-controlling factors, respectively.
Baiyegunhi, Christopher; Gwavava, Oswald
2017-03-01
The southeastern Karoo Basin is considered to be one of the most prospective areas for shale gas exploration in South Africa. An interesting magnetic anomaly, the Beattie magnetic anomaly (BMA), and geologic intrusions are seen on the magnetic map. To date, the source of the BMA and interconnectivity of the igneous intrusions are not well understood. In this study, we investigate the interconnectivity of the igneous intrusions and possible location of the source of the BMA using gravity and magnetic methods. The gravity model results showed that igneous intrusions are interconnected at depth, which probably pose threat by increasing the risk of fracking the Karoo for shale gas exploration. The magnetic results revealed that the BMA becomes stronger with depth. The average depths to the top of the shallow and deep magnetic sources were estimated to be approximately 0.6 and 15 km, respectively.
Cowie, Leanne; Kusznir, Nick; Horn, Brian
2014-05-01
Integrated quantitative analysis using deep seismic reflection data and gravity inversion have been applied to the S Angolan and SE Brazilian margins to determine OCT structure, COB location and magmatic type. Knowledge of these margin parameters are of critical importance for understanding rifted continental margin formation processes and in evaluating petroleum systems in deep-water frontier oil and gas exploration. The OCT structure, COB location and magmatic type of the S Angolan and SE Brazilian rifted continental margins are much debated; exhumed and serpentinised mantle have been reported at these margins. Gravity anomaly inversion, incorporating a lithosphere thermal gravity anomaly correction, has been used to determine Moho depth, crustal basement thickness and continental lithosphere thinning. Residual Depth Anomaly (RDA) analysis has been used to investigate OCT bathymetric anomalies with respect to expected oceanic bathymetries and subsidence analysis has been used to determine the distribution of continental lithosphere thinning. These techniques have been validated for profiles Lusigal 12 and ISE-01 on the Iberian margin. In addition a joint inversion technique using deep seismic reflection and gravity anomaly data has been applied to the ION-GXT BS1-575 SE Brazil and ION-GXT CS1-2400 S Angola deep seismic reflection lines. The joint inversion method solves for coincident seismic and gravity Moho in the time domain and calculates the lateral variations in crustal basement densities and velocities along the seismic profiles. Gravity inversion, RDA and subsidence analysis along the ION-GXT BS1-575 profile, which crosses the Sao Paulo Plateau and Florianopolis Ridge of the SE Brazilian margin, predict the COB to be located SE of the Florianopolis Ridge. Integrated quantitative analysis shows no evidence for exhumed mantle on this margin profile. The joint inversion technique predicts oceanic crustal thicknesses of between 7 and 8 km thickness with
Gamow, George
2003-01-01
A distinguished physicist and teacher, George Gamow also possessed a special gift for making the intricacies of science accessible to a wide audience. In Gravity, he takes an enlightening look at three of the towering figures of science who unlocked many of the mysteries behind the laws of physics: Galileo, the first to take a close look at the process of free and restricted fall; Newton, originator of the concept of gravity as a universal force; and Einstein, who proposed that gravity is no more than the curvature of the four-dimensional space-time continuum.Graced with the author's own draw
Ben Achour, Jibril; Brahma, Suddhasattwa; Marcianò, Antonino
2017-07-01
Using self-dual Ashtekar variables, we investigate (at the effective level) the spherically symmetry reduced model of loop quantum gravity, both in vacuum and when coupled to a scalar field. Within the real Ashtekar-Barbero formulation, the system scalar field coupled to spherically symmetric gravity is known to possess a non closed (quantum) algebra of constraints once local (pointwise) holonomy corrections are introduced, which leads to several obstructions in the loop quantization of the model. Moreover, the vacuum case, while not anomalous, introduces modifications which have been suggested to be an effective signature change of the metric in the deep quantum region. We show in this paper that both those complications disappear when working with self-dual Ashtekar variables, both in the vacuum case and in the case of gravity minimally coupled to a scalar field. In this framework, the algebra of the holonomy corrected constraints is anomaly free and reproduces the classical hypersurface deformation algebra without any deformations. A possible path towards quantization of this model is briefly discussed.
Relation between Gravity Field Feature and Tectonics and Earthquakes in Taiwan and Its Adjacent Seas
张赤军; 方剑
2001-01-01
Short wave gravity anomaly is correlated to sea floor topography in the gravity field of Taiwan and its adjacent seas. Gravity values of 200 × 10-5ms-2 at Yushang and -160 × 10-5ms-2 at Liuqiu sea trench are respectively the maximum and minimum gravity values in this area.Bouguer gravity anomaly reflects not only Moho interface undulation, but also fault distribution.The inflexion of gradient belt of Bouguer gravity anomaly is a spot liable to earthquakes. Middlelong wave geoid is the best data to invert crustal thickness. We calculate crustal thickness by using geoid data, and the maximum value is 38km; the minimum value is 12km in Taiwan and its adjacent seas.
Sreejith, K.M.; Rajesh, S.; Majumdar, T.J.; Rao, G.S.; Radhakrishna, M.; Krishna, K.S.; Rajawat, A.S.
spherical harmonic coefficients of Earth Gravity Model 2008 (EGM2008) up to degree and order 50 from the observed geoid data. The coefficients are smoothly rolled off between degrees 30-70 in order to avoid artifacts related to the sharp truncation at degree...
Blakely, Richard J. [U.S. Geological Survey, Menlo Park, CA (United States); Sherrod, Brian [U.S. Geological Survey, Seattle, WA (United States); Weaver, Craig [U.S. Geological Survey, Seattle, WA (United States); Wells, Ray E. [U.S. Geological Survey, Menlo Park, CA (United States); Rohay, Alan C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2013-11-13
Magnetic and gravity data, collected in south-central Washington near the Yakima Fold and Thrust Belt (YFTB) are used to model upper crustal structure, the extent of the late Columbia River Basalt flow named the Ice Harbor member, the vertical conduits (dikes) that the Ice Harbor erupted from, and whether the dikes are offset or affected by faulting on the Wallula Fault zone.
National Oceanic and Atmospheric Administration, Department of Commerce — The Decade of North American Geology (DNAG) gravity grid values, spaced at 6 km, were used to produce the Gravity Anomaly Map of North America (1987; scale...
Datsenko, I.; Lozovenko, O.; Minaiev, Yu
2016-09-01
In their recent paper, Wang and Su (2015 Eur. J. Phys. 36 055010) acquainted readers with a solution to a problem about the optimal shape of an object for generating a maximum gravity field at a given point in space. After applying the variational principal and the Euler-Lagrange equation they obtained the shape for two-, three- and arbitrary n-dimensional cases. We are convinced that the problem is interesting enough to consider it with students. In this Comment we will try to present an easier way to solve it for the three-dimensional space.
Liu, Shen; Feng, Caixia; Feng, Guangying; Xu, Mengjing; Coulson, Ian M.; Guo, Xiaolei; Guo, Zhuang; Peng, Hao; Feng, Qiang
2017-09-01
Six mafic dyke swarms crop out in Hebei Province within the Taihang-Da Hinggan gravity lineament magmatic belt, China, and were sampled. Here, we present new zircon laser ablation-inductively coupled plasma-mass spectrometry U-Pb age, whole rock geochemical, and Sr-Nd-Pb-Hf isotopic data for the six areas where these mafic dykes occur. The mafic (dolerite) dykes formed between 131.6 ± 1.6 and 121.6 ± 1.1 Ma, and are enriched in the light rare earth elements (LREE), some of the large ion lithophile elements (LILE; e.g., Rb, Ba, and Sr) and Pb, and are depleted in Th, U, Nb and Ta; some samples are also depleted in Eu. The dykes have high initial 87Sr/86Sr ratios (0.7055-0.7057), negative εNd (t) values (-12.5 to -11.9), relatively constant Pb isotopic ratios ((206Pb/204Pb)i = 16.45-16.51, (207Pb/204Pb)i = 15.44-15.51, (208Pb/204Pb)i = 36.49-36.53), negative εHf (t) values (-18.2 to -15.1), and old Nd (TNdDM2; 2.17-2.47 Ga) and Hf (THfDM2; 2.28-2.33 Ga) model ages. These geochronological, geochemical, and isotopic data indicate that the dykes were derived from magmas generated by low to moderate degree partial melting (1.0%-10%) of an EM1-like garnet lherzolite mantle source; these magmas fractionated olivine, clinopyroxene, and hornblende prior to emplacement, and assimilated minimal amounts of crustal material. Several possible models have previously been proposed to explain the origin of Mesozoic magmatism in this region. However, here we propose a foundering model for these studied mafic dykes, involving the foundering of eclogite from thickened lower crust due to the collision between the Siberian Craton and the North China Craon.
Kim, Y. M.; Lee, S. M.
2016-12-01
Marginal basins located between the continent and arc islands often exhibit diverse style of opening, from regions that appear to have formed by well-defined and localized spreading center to those with less obvious zones of extension and a broad magmatic emplacement in the lower crust. The difference in the mode of back-arc opening may lead to a marked difference in crustal structure including its overall thickness and mechanical strength. The Ulleung Basin (UB) in the East Sea/Sea of Japan is considered to represent a continental rifting end-member of back-arc opening. However, compared to nearby Yamato Basin (YB) and Japan Basin (JB) in the NE corner of the sea, its structure and crustal characteristics are less well understood. This study examines the marine gravity anomalies of the UB in order to delineate the variations in crustal structure. Our analysis shows that the Moho depth from the sea surface varies from 16 km at the basin center to 22 km at the margins. However, within the basin center, the inferred thickness of the crust not including sediment is more or less the same (10-12 km), by varying only about 10-20% of the total thickness, contrary to the previous suggestions. The revelation that the UB has a thick but uniform thickness crust is consistent with previous observations using ocean bottom seismometers and is similar recent findings from the nearby YB. Another important feature is that small residual mantle gravity anomaly highs (40 mGal) exist in the northern part of the basin. These small highs trend in the NNE-SSW direction and thus corresponding to the orientation of the major tectonic structures on the Korean Peninsula, raising the possibility that they are the result of localized extension and extra crustal thinning at the time of basin formation. Alternatively, the presence of small magmatic underplating at the base of the crust, perhaps similar to high velocity region in the lower crust of YB, was also considered. According to our study
Samudrala, Kiranmai; Kamesh Raju, K. A.; Rao, P. Rama
2016-12-01
High-resolution shipboard geophysical investigations along the Indian Ocean ridge system are sparse especially over the Carlsberg and Central Indian ridges. In the present study, the shipboard gravity and multibeam bathymetry data acquired over a 750 km long section of the Central Indian Ridge between 3 ∘S and 11 ∘S have been analysed to understand the crustal structure and the ridge segmentation pattern. The mantle Bouguer anomalies (MBA) and the residual mantle Bouguer anomalies (RMBA) computed in the study area have shown significant variations along the ridge segments that are separated by transform and non-transform discontinuities. The MBA lows observed over the linear ridge segments bounded by well-defined transform faults are attributed to the thickening of the crust at the middle portions of the ridge segments. The estimates of crustal thickness from the RMBA shows an average of 5.2 km thick crust in the axial part of the ridge segments. The MBA and relative RMBA highs along the two non-transform discontinuities suggests a thinner crust of up to 4.0 km. The most significant MBA and RMBA highs were observed over the Vema transform fault suggesting thin crust of 4 km in the deepest part of the transform fault where bathymetry is more than 6000 m. The identified megamullion structures have relative MBA highs suggesting thinner crust. Besides MBA lows along the ridge axis, significant off-axis MBA lows have been noticed, suggesting off-axis mantle upwelling zones indicative of thickening of the crust. The rift valley morphology varies from the typical V-shaped valley to the shallow valley floor with undulations on the inner valley floor. Segments with shallow rift valley floor have depicted well-defined circular MBA lows with persistent RMBA low, suggesting modulation of the valley floor morphology due to the variations in crustal thickness and the mantle temperature. These are supported by thicker crust and weaker lithospheric mantle.
Kiranmai Samudrala; K A Kamesh Raju; P Rama Rao
2016-12-01
High-resolution shipboard geophysical investigations along the Indian Ocean ridge system are sparse especially over the Carlsberg and Central Indian ridges. In the present study, the shipboard gravity and multibeam bathymetry data acquired over a 750 km long section of the Central Indian Ridge between 3°S and 11°S have been analysed to understand the crustal structure and the ridge segmentation pattern. The mantle Bouguer anomalies (MBA) and the residual mantle Bouguer anomalies (RMBA) computed in the study area have shown significant variations along the ridge segments that are separated by transform and non-transform discontinuities. The MBA lows observed over the linear ridge segments bounded by well-defined transform faults are attributed to the thickening of the crust at the middle portions of the ridge segments. The estimates of crustal thickness from the RMBA shows an average of 5.2 km thick crust in the axial part of the ridge segments. The MBA and relative RMBA highs along the two nontransform discontinuities suggests a thinner crust of up to 4.0 km. The most significant MBA and RMBA highs were observed over the Vema transform fault suggesting thin crust of 4 km in the deepest part of the transform fault where bathymetry is more than 6000 m. The identified megamullion structures have relative MBA highs suggesting thinner crust. Besides MBA lows along the ridge axis, significant off-axis MBA lows have been noticed, suggesting off-axis mantle upwelling zones indicative of thickening of the crust. The rift valley morphology varies from the typical V-shaped valley to the shallow valley floor with undulations on the inner valley floor. Segments with shallow rift valley floor have depicted well-defined circular MBA lows with persistent RMBA low, suggesting modulation of the valley floor morphology due to the variations in crustal thickness and the mantle temperature. These are supported by thicker crust and weaker lithospheric mantle.
Biswas, A.
2016-12-01
A proficient way to deal with appraisal model parameters from total gradient of gravity and magnetic data in light of Very Fast Simulated Annealing (VFSA) has been exhibited. This is the first run through of applying VFSA in deciphering total gradient of potential field information with another detailing estimation brought on because of detached causative sources installed in the subsurface. The model parameters translated here are the amplitude coefficient (k), accurate origin of causative source (x0) depth (z0) and the shape factor (q). The outcome of VFSA improvement demonstrates that it can exceptionally decide all the model parameters when shape variable is fixed. The model parameters assessed by the present strategy, for the most part the shape and depth of the covered structures was observed to be in astounding concurrence with the genuine parameters. The technique has likewise the capability of dodging very uproarious information focuses and enhances the understanding results. Investigation of Histogram and cross-plot examination likewise proposes the translation inside the assessed ambiguity. Inversion of noise-free and noisy synthetic data information for single structures and field information shows the viability of the methodology. The procedure has been carefully and adequately connected to genuine field cases (Leona Anomaly, Senegal for gravity and Pima copper deposit, USA for magnetic) with the nearness of mineral bodies. The present technique can be to a great degree material for mineral investigation or ore bodies of dyke-like structure rooted in the shallow and more deep subsurface. The calculation time for the entire procedure is short.
Lee, Sang-Mook; Kim, Yoon-Mi
2016-04-01
Marginal basins locate between the continent and arc islands often exhibit diverse style of opening, from regions that appear to have formed by well-defined and localized spreading center (manifested by the presence of distinct seafloor magnetic anomaly patterns) to those with less obvious zones of extension and a broad magmatic emplacement most likely in the lower crust. Such difference in the style of back-arc basin formation may lead to marked difference in crustal structure in terms of its overall thickness and spatial variations. The Ulleung Basin, one of three major basins in the East Sea/Sea of Japan, is considered to represent a continental rifting end-member of back-arc opening. Although a great deal of work has been conducted on the sedimentary sections in the last several decades, the deep crustal sections have not been systematically investigated for long time, and thus the structure and characteristics of the crust remain poorly understood. This study examines the marine gravity anomalies of the Ulleung Basin in order to understand the crustal structure using crucial sediment-thickness information. Our analysis shows that the Moho depth in general varies from 16 km at the basin center to 22 km at the margins. However, within the basin center, the inferred thickness of the crust is more or less the same (10-12 km), thus by varying only about 10-20% of the total thickness, contrary to the previous impression. The almost-uniformly-thick crust that is thicker than a normal oceanic crust (~ 7 km) is consistent with previous observations using ocean bottom seismometers and recent deep seismic results from the nearby Yamato Basin. Another important finding is that small residual mantle gravity anomaly highs exist in the northern part of the basin. These highs are aligned in the NNE-SSW direction which correspond to the orientation of the major tectonic structures on the Korean Peninsula, raising the possibility that, though by a small degree, they are a
Comparison of Present SST Gravity Field Models
LUO Jia; SHI Chuang; ZOU Xiancai; WANG Haihong
2006-01-01
Taking the main land of Europe as the region to be studied, the potential of the new satellite gravity technique: satellite-to-satellite tracking (SST) and improving the accuracy of regional gravity field model with the SST models are investigated. The drawbacks of these models are discussed. With GPM98C as the reference, the gravity anomaly residuals of several other models, the latest SST global gravity field models (EIGEN series and GGM series), were computed and compared. The results of the comparison show that in the selected region, some systematic errors with periodical properties exist in the EIGEN and GGM's S series models in the high degree and order. Some information that was not shown in the classic gravity models is detected in the low and middle degree and order of EIGEN and GGM's S series models. At last, the effective maximum degrees and orders of SST models are suggested.
Ramana, M.V.
of Alaska and Japan trench, east of the Japanese Islands. Gravity anomalies across continental margins Continental margins are at or near to the transition zone between continental and oceanic crusts. Passive margins are commonly in isostatic.... Generalized bathymetry map of the Indian continental margins After Mishra et al., (2004) The western and eastern margins of India are classified under passive/Atlantic type continental margins, and the structural architecture is similar to any...
Gravity Station Data for Portugal
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data total 3064 records. This data base was received in April 1997. Principal gravity parameters include Free-air Anomalies which have been...
Interior Alaska Gravity Station Data
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data total 9416 records. This data base was received in March 1997. Principal gravity parameters include Free-air Anomalies which have been...
Gravity Station Data for Spain
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data total 28493 records. This data base was received in April 1997. Principal gravity parameters include Free-air Anomalies which have been...
王伟; 李姗姗; 马彪; 高新兵
2013-01-01
The method of establishing the mean free-air gravity anomaly reference field with rare gravity data has been studied based on the Airy and Heiskanen isostatic theory.The numerical model of the mean free-air gravity anomalies has been established using the regional high-resolution topographic data; then for the problem that the systematic errors existed in the computational area,a few of gravimetric points have been chosen as constraint points in order to eliminate errors.Finally,the comparisons have been made among the gravity field model of EGM2008 and interpolation using separate points.As a result,the method could get better precision than two other methods as well as could reduce workloads in gravity measurement in the fields,the method is suitable for establishing the mean free-air gravity anomalies in difficult conditions.%研究基于Airy-Heiskanen均衡理论构建重力控制点稀少区域平均空间重力异常参考场的方法.利用区域高分辨率地形数据构建平均空间重力异常数值模型；针对均衡理论构建重力异常存在系统性误差的问题,研究了布设少量重力观测点作为约束,对所构建的平均空间重力异常数值模型的系统性误差进行修正,并与基于EGM2008重力场模型以及基于少量离散点直接内插推估构建区域平均空间重力异常的方法进行对比.结果表明,该方法得到的计算值精度明显优于后两者,同时能大大减少重力测量的工作量,且适宜于困难地区平均空间重力异常的填补.
National Oceanic and Atmospheric Administration, Department of Commerce — In 1985, Dr. William F. Haxby of the Lamont-Doherty Geological Observatory of Columbia University prepared this data base of free-air gravity anomalies, based on the...
M.P. Martínez
2003-06-01
Full Text Available En este trabajo se presenta un perfil gravimétrico ubicado en la provincia de La Rioja (Argentina a la latitud aproximada de 29° Sur. Se aplican métodos gravimétricos de máxima profundidad, encontrándose que bajo la sierra de Famatina la anomalía de masa se ubica en corteza inferior. Mientras que para la sierra de Velasco las máximas profundidades de las masas anómalas se indican para la corteza superior, en total coherencia con resultados anteriores. Se analiza la significativa correspondencia entre las estructuras geológicas y el campo potencial gravimétrico. La señal gravimétrica revela sin duda la zona de sutura existente entre la Precordillera y la sierra de Famatina, como así también la zona de cizalla entre la sierra de Famatina y la sierra de Velasco. Basándose en los resultados geofísicos y en las últimas investigaciones geológicas, se propone un modelo colisional (Modelo Cortical II que describe la relación entre los terrenos Chilenia, Cuyania, Famatina y Pampia. Este modelo responde coherentemente a la anomalía de Bouguer observada.A gravity profile located in La Rioja province (Argentina at an approximate latitude of 29° S. was analysed. Application of gravimetric methods of maximum depth shows that, under the Famatina Range, the anomaly of mass is located in lower crust. By contrast, in the Velasco Range, the maximum depths of the anomalous masses are within the upper crust, a result in total agreement with previous results. The significant correspondence between the geological structures and the gravity field was alalysed. The gravity signal reveals clearly the zone of the suture present between the Precordillera and the Sierra of Famatina, as well as the shears zone between the Famatina and Velasco ranges. Using our geophysical results and previous geological investigations, we propose a collision model (II Cortical Model that describes the relationship between the Chilenia, Cuyania, Famatina and Pampia
Samudrala, K.; KameshRaju, K.A; RamaRao, P.
High-resolution shipboard geophysical investigations along the Indian Ocean ridge system are sparse especially over the Carlsberg and Central Indian ridges. In the present study, the shipboard gravity and multibeam bathymetry data acquired over a...
Langenheim, Victoria; Jachens, Robert C.; Clynne, Michael A.; Muffler, L. J. Patrick
2016-01-01
Interpretation of magnetic and new gravity data provides constraints on the geometry of the Hat Creek Fault, the amount of right-lateral offset in the area between Mt. Shasta and Lassen Peak, and confirmation of the influence of pre-existing structure on Quaternary faulting. Neogene volcanic rocks coincide with short-wavelength magnetic anomalies of both normal and reversed polarity, whereas a markedly smoother magnetic field occurs over the Klamath Mountains and its Paleogene cover. Although the magnetic field over the Neogene volcanic rocks is complex, the Hat Creek Fault, which is one of the most prominent normal faults in the region and forms the eastern margin of the Hat Creek Valley, is marked by the eastern edge of a north-trending magnetic and gravity high 20-30 km long. Modeling of these anomalies indicates that the fault is a steeply dipping (~75-85°) structure. The spatial relationship of the fault as modeled by the potential-field data, the youngest strand of the fault, and relocated seismicity suggests that deformation continues to step westward across the valley, consistent with a component of right-lateral slip in an extensional environment. Filtered aeromagnetic data highlight a concealed magnetic body of Mesozoic or older age north of Hat Creek Valley. The body’s northwest margin strikes northeast and is linear over a distance of ~40 km. Within the resolution of the aeromagnetic data (1-2 km), we discern no right-lateral offset of this body. Furthermore, Quaternary faults change strike or appear to end, as if to avoid this concealed magnetic body and to pass along its southeast edge, suggesting that pre-existing crustal structure influenced younger faulting, as previously proposed based on gravity data.
Gravity gradient for Greenland and its tectonic interpretation
Grushinsky, Andrew N.
2013-04-01
Gravity gradient is the indicator of the stress conditions in the lithosphere. The axis of gradient signs changing indicates the boundary of blocks exposed to different tensions. The lines of maxima and minima of gravity gradient correspondingly marked the boundary of zones of compression and expansion. Four various types of the gravity anomalies was calculated: in free air, Bouguer's, Glennie's and isostatic. And then was calculated their gradients. The preliminary analysis of gradients shows, that its qualitative behavior for all types of gravity anomalies is very closely and, therefore, conclusions about the stress conditions in the lithosphere of the considering region are definite. Range of the changing for gradients of gravity in free air anomalies - from -96.1 to 135.8 eötvös, and for gradients of gravity Bouguer's anomalies - from -122.6 to 141.9 eötvös. Range of the changing for gradients of gravity Glennie's and isostatic anomalies are substantially smaller, for gradients of gravity Glennie's anomalies - from -27.6 to 25.5 eötvös, and for gradients of gravity isostatic anomalies - from -19.2 to 21.2 eötvös. This difference in the gradient values, evidently, connects with the difference in the thoroughness and the degree of averaging of the anomalies. Analysis of gravity gradient shown the following: 1. In the western part of the researching region are distinguished three linear structures (two maxima and one minimum), which marked rift zone of the Baffin Bay and Davis Strait. This disappeared rift characterized by depressed zone, lengthened from Nares strait along the west sea coast of Greenland. In the south part of this zone localized deep fault, which northward become lesser expressed. To the north and north-east from the Nares strait lengthened to the North Pole zone of compression, blocked up existing previously rift, by which the rotation of the Greenland part of Canadian shield from its cardinal part happened. Center of this rotation
Uotila, U. A.
1978-01-01
In order to use gravity anomalies in geodetic computations and geophysical interpretations, the observed gravity values from which anomalies are derived should be referred to one consistent world wide system. The International Gravity Standardization Net 1971 was adapted by the International Union of Geodesy and Geophysics at Moscow in 1971, the network was result of extensive cooperation by many organizations and individuals around the world. The network contains more than 1800 stations around the world. The data used in the adjustment included more than 25,000 gravimetry, pendulum and absolute measurements.
Garland, G D; Wilson, J T
2013-01-01
The Earth's Shape and Gravity focuses on the progress of the use of geophysical methods in investigating the interior of the earth and its shape. The publication first offers information on gravity, geophysics, geodesy, and geology and gravity measurements. Discussions focus on gravity measurements and reductions, potential and equipotential surfaces, absolute and relative measurements, and gravity networks. The text then elaborates on the shape of the sea-level surface and reduction of gravity observations. The text takes a look at gravity anomalies and structures in the earth's crust; interp
Rajesh, S.; Majumdar, T.J.; Krishna, K.S.
Among the submarine ridge systems in the northern Indian Ocean, the 85 degree E Ridge in the Bay of Bengal is more enigmatic owing to its peculiar anomalous negative free-air gravity. In general, this has been attributed to the isostatic...
J Kostadinoff
2003-12-01
Full Text Available La sierra de Socoscora se ubica en forma meridiana y se manifiesta como un escalón al noroeste de la Sierra Grande de San Luis. En la sierra de Socoscora las rocas del basamento están representadas por metamorfitas de alto grado con escasos afloramientos de metabasitas. Las mediciones del campo gravitatorio y magnético indican la presencia de un volumen mayor de estas rocas en su subsuelo. Los excesos de masa en esta sierra se hallan definidas por anomalías gravimétricas de Bouguer (residuales positivas similares a las encontradas en la Sierra Grande de San Luis. La magnetometría indica, a partir de las respuestas positivas, la existencia de rocas máficas con concentraciones anómalas de minerales magnéticos.The Sierra de Socoscora is a north - south trending mountain range, located nortwest of the Sierra Grande of San Luis. The basament is constituted by high grade metamorphic rocks with few associated metabasites. Earth gravity and magnetic field measurements are indicative of the presence of bigger volumes of mafic rocks below the surface, which carry anomalous concentrations of ferromagnetic and/or paramagnetic minerals (magnetite and/or sulfides. An excess of mass below this Sierra is shown by Bouguer gravimetric anomalies with magnitudes similar to those measured in the Sierra Grande de San Luis. Positive magnetic anomalies are indicative of the presence of mafic rocks with anomalous concentrations of magnetic minerals.
Isaac Dadzie; 李建成; 褚永海
2008-01-01
Gravity anomalies on a 2.5×2.5 arc-minute grid in a non-tidal system were derived over the South China and Philippine Seas from multi-satellite altimetry data. North and east components of deflections of the vertical were computed from altimeter-derived sea surface heights at crossover locations, and gridded onto a 2.5×2.5 arc-minute resolution grid. EGM96-derived components of deflections of the vertical and gravity anomalies gridded into 2.5×2.5 arc-minute resolutions were then used as reference global geopotential model quantities in a remove-restore procedure to implement the Inverse Vening Meinesz formula via the 1D-FFT technique to predict the gravity anomalies over the South China and Philippine Seas from the gridded altimeter-derived Components of deflections of the vertical. Statistical comparisons between the altime-ter-derived and the shipboard gravity anomalies showed that there is a root-mean-square agreement of 5.7 mgals between them.
Hawaiian Islands Terrain Corrected Free Air Anomalies (96)
National Oceanic and Atmospheric Administration, Department of Commerce — This 2' gravity anomaly grid for the Principal Hawaiian Islands is NOT the input data set used in development of the GEOID96 model. This gravity grid models the...
PR/VI Terrain Corrected Free Air Anomalies (96)
National Oceanic and Atmospheric Administration, Department of Commerce — This 2' gravity anomaly grid for the Puerto Rico and the Virgin Islands is NOT the input data set used in development of the GEOID96 model. This gravity grid models...
文武; 汤克云; 王谦身; 高玉文; 华昌才
2013-01-01
It is a vital problem about the nature of gravity and also a realistic scientific issue whether a gravity anomaly exists during the total solar eclipse. For a century, predecessors did a lot of observations and experiments to research gravity anomalies during the solar eclipses. Nonetheless, a clear result has not been found due to the limitation of the condition and the instruments. On the basis of previous work, this paper studies the gravity data of seven LaCoste-Romberg gravimeters and one SG-053 superconducting gravimeter during the total solar eclipse on July 22, 2009. The study utilized the perfect environment and the delicate instrument. It could to be the best research activity both in the experiment scale and in the observation quality in the past century. Based on the research in this paper, we hold the opinion that the supposed gravity anomaly during the total solar eclipse cannot be detected at present with actual observation conditions and instrument performance. And the previous anomaly was very likely created by the drastic changes in the weather. Moreover, the least square cubic-polynomial fitting method which is used to remove the theoretical earthtide from the observed gravity data makes a more simple calculation and a more reliable conclusion.%日全食期间在是否存在“引力异常”现象是一个关系到引力本质的重大问题,也是一个十分具有现实意义的科学问题.近一个世纪来,许多科学工作者作了大量的观测和实验,研究日全食期间的“引力异常”现象.肯定的、否定的结果并存,更多的是难以确定的结果.在学习、总结和发展了前人工作的基础之上,本文利用7台LaCoste-Romberg重力仪和1台SG-053超导重力仪,对2009年7月22日日全食期间的重力变化进行了精细的观测.研究利用了目前最好的观测环境和观测仪器,无论观测规模还是观测质量在近百年来日全食的重力观测研究中都是首屈一指的.在经过
The "Parity" Anomaly On An Unorientable Manifold
Witten, Edward
2016-01-01
The "parity" anomaly -- more accurately described as an anomaly in time-reversal or reflection symmetry -- arises in certain theories of fermions coupled to gauge fields and/or gravity in a spacetime of odd dimension. The "parity" anomaly has traditionally been studied on orientable manifolds only, but recent developments involving topological superconductors have made it clear that one can get more information by asking what happens on an unorientable manifold. In this paper, we analyze the "parity" anomaly for fermions coupled to gauge fields and gravity in $2+1$ dimensions. We consider applications to gapped boundary states of a topological superconductor and to M2-branes in string/M-theory.
Mexico Terrain Corrected Free Air Anomalies (97)
National Oceanic and Atmospheric Administration, Department of Commerce — This 2' gravity anomaly grid for Mexico, North-Central America and the Western Caribbean Sea is NOT the input data set used in the development of the MEXICO97 model....
翟振和; 孙中苗; 任红飞; 杨坤
2012-01-01
在空域,利用严密的向上延拓公式将地面重力数据上延至空中不同高度,而后与相应的地面重力数据比较从而得到不同高度的代表误差.在频域,构建了新的代表误差模型,计算了不同高度、不同分辨率下的代表误差.实际算例表明,在空域,对于地形平坦区域,在1 km高度以下,5'空中重力数据直接代表地面重力数据的误差小于1×10-5 m/s2.对于地形复杂区域；当空中测量高度大于1 km时,空中重力数据的代表误差大于3.3×10-5 m/s2,因此必须考虑向下延拓的问题.在频域,当高度小于7 km时,代表误差与高度及分辨率之间不再是简单的线性关系；当高度大于7 km时,代表误差随着分辨率的减小而减小,随着高度的增加而增加.%In space domain, air gravity data can be acquired by upward continuation of land gravity data based on the rigorous integral formula. Then the representative error can be obtained through the comparison between the air gravity data and corresponding land gravity data. The actual computation results show that the representative error of 5' air gravity data is about 1 × 10-5 m/s2 m flat area under the 1 km height. For the area yf complex terrain, the representative error is about 3. 3× 10-5 m/V when the surveying height is more than 1 km, so the downward continuation must be considered in the use of airborne gravimetry data. In frequency domain, the new gravity anomaly degree variance model is constructed based on EGM2008 model. Then the representative error of different height and different resolution are computed in frequency domain. The results show that the relationship between representative error and height is not simply the linear relation when the height is smaller than 7 km, and the representative error is becoming smaller with the resolution reducing.
Alaska Terrain Corrected Free Air Anomalies (96)
National Oceanic and Atmospheric Administration, Department of Commerce — This 2' x 4' gravity anomaly grid for Alaska is NOT the input data set used in development of the GEOID96 model. This gravity grid models the 1.1 million terrestrial...
Afshar, A.; Norouzi, G. H.; Moradzadeh, A.; Riahi, M. A.; Porkhial, S.
2017-03-01
Prospecting the geothermal resources in northwest of Iran, conducted in 1975, revealed several promising areas and introduced the Sabalan geothermal field as a priority for further studies. The Sabalan Mt., representing the Sabalan geothermal field, is a large stratovolcano which consists of an extensive central edifice built on a probable tectonic horst of underlying intrusive and effusive volcanic rocks. In this study, Curie point depth (CPD), geothermal gradient and heat-flow map were constituted from spectral analysis of the aeromagnetic data for the NW of Iran. The top of the geothermal resource (i.e., the thickness of the overburden) was evaluated by applying the Euler deconvolution method on the residual gravity data. The thickness of the geothermal resource was calculated by subtracting the Euler depths obtained from the CPDs in the geothermal anomalous region. The geothermal anomalous region was defined by the heat-flow value greater than 150 mW/m2. CPDs in the investigated area are found between 8.8 km in the Sabalan geothermal field and 14.1 in the northeast. The results showed that the geothermal gradient is higher than 62 °C/km and the heat-flow is higher than 152 mW/m2 for the geothermal manifestation region; the thickness of the geothermal resource was also estimated to vary between 5.4 and 9.1 km. These results are consistent with the drilling and other geological information. Findings indicate that the CDPs agree with earthquake distribution and the type of thermal spring is related to the depth of the top of the geothermal resource.
Afshar, A.; Norouzi, G. H.; Moradzadeh, A.; Riahi, M. A.; Porkhial, S.
2016-12-01
Prospecting the geothermal resources in northwest of Iran, conducted in 1975, revealed several promising areas and introduced the Sabalan geothermal field as a priority for further studies. The Sabalan Mt., representing the Sabalan geothermal field, is a large stratovolcano which consists of an extensive central edifice built on a probable tectonic horst of underlying intrusive and effusive volcanic rocks. In this study, Curie point depth (CPD), geothermal gradient and heat-flow map were constituted from spectral analysis of the aeromagnetic data for the NW of Iran. The top of the geothermal resource (i.e., the thickness of the overburden) was evaluated by applying the Euler deconvolution method on the residual gravity data. The thickness of the geothermal resource was calculated by subtracting the Euler depths obtained from the CPDs in the geothermal anomalous region. The geothermal anomalous region was defined by the heat-flow value greater than 150 mW/m2. CPDs in the investigated area are found between 8.8 km in the Sabalan geothermal field and 14.1 in the northeast. The results showed that the geothermal gradient is higher than 62 °C/km and the heat-flow is higher than 152 mW/m2 for the geothermal manifestation region; the thickness of the geothermal resource was also estimated to vary between 5.4 and 9.1 km. These results are consistent with the drilling and other geological information. Findings indicate that the CDPs agree with earthquake distribution and the type of thermal spring is related to the depth of the top of the geothermal resource.
Gripaios, Ben [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Rd., Oxford OX1 3NP (United Kingdom); Merton College, Oxford OX1 4JD (United Kingdom)], E-mail: b.gripaios1@physics.ox.ac.uk; West, Stephen M. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Rd., Oxford OX1 3NP (United Kingdom)], E-mail: s.west1@physics.ox.ac.uk
2008-01-21
We consider, in the effective field theory context, anomalies of gauge field theories on a slice of a five-dimensional, anti-de Sitter geometry and their four-dimensional, holographic duals. A consistent effective field theory description can always be found, notwithstanding the presence of the anomalies and without modifying the degrees of freedom of the theory. If anomalies do not vanish, the d=4 theory contains additional pseudoscalar states, which are either present in the low-energy theory as physical, light states, or are eaten by (would-be massless) gauge bosons. We show that the pseudoscalars ensure that global anomalies of the four-dimensional dual satisfy the 't Hooft matching condition and comment on the relevance for warped models of electroweak symmetry breaking.
Dating of the 85 degrees E Ridge (northeastern Indian Ocean) using marine magnetic anomalies
Michael, L.; Krishna, K.S.
anomalies: the north part (up to 5°N latitude) is associated with negative gravity anomaly, whereas the south part coin- cides with positive gravity anomaly. In contrast to this, the ridge consists of alternate streaks of positive and negative magnetic...
New isostatic model of the lithosphere and gravity field
Kaban, M. K.; Schwintzer, P.; Reigber, Ch.
2003-04-01
A new global model of the isostatic gravity field based on the up-to-date data sets is computed in terms of gravity and geoid. The initial gravity field model is improved using the new CHAMP data. For a construction of the isostatic model of the lithosphere we use the latest compilation of crustal data. Globally this is the CRUST2.0 model, which is supplemented by detailed original data for large parts of North America and North Eurasia. The long-wavelengths of the computed isostatic anomalies up to spherical harmonic degree 20 reflect deep density heterogeneities and the influence of mantle convection through the dynamic topography. The signal contribution of the isostatically balanced lithosphere to the observed gravity or geoid is still significant also for the long-wavelengths: -30- +60 mGal and -15- +40 m peak-to-peak, respectively. Generally the long-wavelength isostaticaly reduced gravity field has much less correlation with the lithosphere patterns than the observed field. This demonstrates that the long-wavelength isostatic gravity field is more appropriate for a modelling of mantle convection than the observed one. The smaller scale isostatic anomalies (wavelengths less than 2000 km) on the other hand are highly sensitive to the quality of the input data used for their computation. To a large extent they reflect internal crustal density inhomogeneities, not included in the isostatic compensation scheme, and uncertainties in the initial crustal data. Thus, small-scale isostatic anomalies may not be always interpreted as a measure of the disturbances of isostatic balance of the lithosphere. Instead we suggest to compute for the smaller scale spectral part the non-isostatic residual topography. The initial crust - upper mantle density model is corrected by gravity inversion in a least squares adjustment. Then, the residual (unbalanced) topography computed with the corrected density distribution represents the isostatic state of the lithosphere. The maximum
张社荣; 王超; 孙博; 王高辉
2013-01-01
The performance failure of the gravity dam under ultimate seismic load is on important characteristic which means its aseismic capability has reached the limit,but there is no unified standard reference to make the evaluation. Based on the characteristics of typical engineering and the potential failure modes,with performance-based seismic damage assessment model,cracking behavior analysis model as well as the foundation stabilization safety and limit load carrying capacity analysis model,the maximum aseismic capability was studied and evaluated by focusing the emphasis on damage levels,cracking extending mode,foundation load carrying capacity and displacement jump of typical position for the gravity dams on complex layered rock foundation. Example results show that the maximum aseismic capability of the overfall section of Ahai gravity dam is evaluated as 0.550g—0.600g. The proposed method has been successfully applied to the maximum aseismic capability evaluation by considering the comprehensive influ-ence of the key performance failure.It avoids the shortage of the single convergence or abrupt system changeover criteria,and also overcomes the shortage of the experimental research to some extent.% 针对复杂层状岩基上典型工程的特点，从结构系统功能的潜在失效模式出发，利用数值仿真分析方法，结合基于功能的地震破坏等级评价模型、基于断裂力学的坝体开裂行为分析模型和基于变形体突变的系统极限承载力分析评价模型，建议从坝体混凝土损伤破坏等级、开裂破坏模式、坝基岩体极限承载能力和系统稳定性突变等方面综合评价大型重力坝的极限抗震能力.实例分析结果表明，阿海重力坝溢流坝段极限抗震能力为0.550g~0.600g.基于数值试验的极限抗震能力综合评估方法，可以全面考虑各种关键性能对极限抗震能力的影响，避免了单一收敛性或系统突变评价准则的缺陷，在
Phenomenological Quantum Gravity
Kimberly, D; Kimberly, Dagny; Magueijo, Joao
2005-01-01
These notes summarize a set of lectures on phenomenological quantum gravity which one of us delivered and the other attended with great diligence. They cover an assortment of topics on the border between theoretical quantum gravity and observational anomalies. Specifically, we review non-linear relativity in its relation to loop quantum gravity and high energy cosmic rays. Although we follow a pedagogic approach we include an open section on unsolved problems, presented as exercises for the student. We also review varying constant models: the Brans-Dicke theory, the Bekenstein varying $\\alpha$ model, and several more radical ideas. We show how they make contact with strange high-redshift data, and perhaps other cosmological puzzles. We conclude with a few remaining observational puzzles which have failed to make contact with quantum gravity, but who knows... We would like to thank Mario Novello for organizing an excellent school in Mangaratiba, in direct competition with a very fine beach indeed.
Global Gravity Grids, Geoid Height and Gravity Anomaly Profiles
National Oceanic and Atmospheric Administration, Department of Commerce — The entire collection of GEOSAT ERM (Nov.'86 - Dec. '89) data over land and ice regions is held at the National Geophysical Data Center (NGDC). These data will yield...
Durante, D.; Iess, L.; Racioppa, P.; Armstrong, J. W.; Lunine, J. I.; Stevenson, D. J.; Tortora, P.
2016-12-01
Since its arrival at Saturn in 2004, Cassini performed nine flybys devoted to the determination of Titan's gravity field and its tidal variations. The last gravity flyby of the mission (T122) took place on Aug. 10, 2016. We will present an updated gravity solution, based on all available data. These include also an additional flyby (T110, March 2015, primarily devoted to the imaging Titan's north polar lakes) carried out with the low gain antenna. This flyby was particularly valuable because closest approach occurred at high latitude (75°N), over an area not previously sampled. Published gravity results (Iess et al., 2012) indicated that Titan is subject to large eccentricity tides in response to Saturn's time varying forcing field. The magnitude of the response quadrupole field, controlled by the Love number k2, was used to infer the existence of an internal ocean. The new gravity field determination provides a better estimate of k2, to a level of a few percent. In addition to a full 3x3 field, the new solution includes also higher degree and order harmonic coefficients (such as J4) and offers an improved map of gravity anomalies. The updated geoid and its associated uncertainty could be used to refine the gravity-altimetry correlative analysis and for improved interpretation of radar altimetric data.
Modeling of Earth's Gravity Fields Visualization Based on Quad Tree
LUO Zhicai; LI Zhenhai; ZHONG Bo
2010-01-01
The problems of the earth's gravity fields' visualization are both focus and puzzle currently. Aiming at multiresolution rendering, modeling of the Earth's gravity fields' data is discussed in the paper by using LOD algorithm based on Quad Tree. First,this paper employed the method of LOD based on Quad Tree to divide up the regional gravity anomaly data, introduced the combined node evaluation system that was composed of viewpoint related and roughness related systems, and then eliminated the T-cracks that appeared among the gravity anomaly data grids with different resolutions. The test results demonstrated that the gravity anomaly data grids' rendering effects were living, and the computational power was low. Therefore, the proposed algorithm was a suitable method for modeling the gravity anomaly data and has potential applications in visualization of the earth's gravity fields.
Mather, R. S.
1973-01-01
Procedures for obtaining position from surface gravity observations are reviewed and their relevance assessed in the context of the application of modern geodetic techniques to programs of Earth and ocean physics. Solutions based on the use of surface layer techniques, the discrete value approach, and the development from Green's theorem are stated in summary, the latter being extended to order e cubed in the height anomaly. The representation of the surface gravity field which is required in order that this accuracy may be achieved is discussed. Interim techniques which could be used in the absence of such a representation are also outlined.
Former Soviet Union (FSU) Gravity Data
National Oceanic and Atmospheric Administration, Department of Commerce — Gridded gravity anomaly data for the Former Soviet Union (FSU) and Eastern Europe has been received by the National Geophysical Data Center(NGDC). The data file...
The origin of lunar mascons - Analysis of the Bouguer gravity associated with Grimaldi
Phillips, R. J.; Dvorak, J.
Grimaldi is a relatively small multi-ringed basin located on the western limb of the moon. Spacecraft free-air gravity data reveal a mascon associated with the inner ring of this structure, and the topographic correction to the local lunar gravity field indicates a maximum Bouguer anomaly of +90 milligals at an altitude of 70 kilometers. Approximately 20% of this positive Bouguer anomaly can be attributed to the mare material lying within the inner ring of this basin. From a consideration of the Bouguer gravity and structure of large lunar craters comparable in size to the central basin of Grimaldi, it is suggested that the remaining positive Bouguer anomaly is due to a centrally uplifted plug of lunar mantle material. The uplift was caused by inward crustal collapse which also resulted in the formation of the concentric outer scarp of Grimaldi. In addition, an annulus of low density material, probably a combination of ejecta and in situ breccia, is required to fully reproduce the Bouguer gravity signature across this basin. It is proposed that Grimaldi supplies a critical test in the theory of mascon formation: crustal collapse by ring faulting and central uplift to depths of the crust-mantle boundary are requisites
Environmental applications of gravity surveying
Barrows, L.J. (Illinois State Univ., Normal, IL (United States)); Nesbit, L.C. (KEMRON Environmental Services, Novi, MI (United States)); Khan, W.A. (Environmental Science Engineering, Phoenix, AZ (United States))
1994-04-01
The Allis Park Sanitary Landfill Company developed a new landfill near Onway, Michigan in an area which has glacial alluvium and glacial till overlying limestone. There are several solution karst features in the region and some critics had maintained that a new karst collapse could rupture the liner system and allow escape of leachate into the groundwater. The gravity survey was conducted to determine the extent of any karst development at the site. The first portion of the survey was two profiles over some karst features located about five miles southeast of the proposed landfill. These showed negative gravity anomalies. The survey of the proposed landfill site resulted in a 50 microGal contour map of the area and also showed a negative anomaly. This could be due to either elevation variations on the till to limestone bedrock surface or to karst development within the limestone. Because there was no evidence of historic development of new karst features in the region, the gravity anomaly was not further investigated. In another gravity survey, a large retail department store had been remodeled and extended over an area previously occupied by an auto service center. The removal of a waste oil storage tank (UST) had not been documented and the environmental consultant (KEMRON, Inc.) proposed that a gravity survey be used to find the tank location. This proposal was based on calculations of the gravity effects of a UST. The survey resulted in a four-microGal contour map which showed a couple of anomalies which could be due to a tank or a backfilled tank excavation. During the survey, a store employee identified the previous location of the tank and explained that she had personally witnessed its removal. Based on the employee's eye-witness account of the tank removal and the coincidence of her indicated tank location with one of the gravity anomalies the authors recommended the site be granted clean closure.
A data-driven approach to local gravity field modelling using spherical radial basis functions
Klees, R.; Tenzer, R.; Prutkin, I.; Wittwer, T.
2008-01-01
We propose a methodology for local gravity field modelling from gravity data using spherical radial basis functions. The methodology comprises two steps: in step 1, gravity data (gravity anomalies and/or gravity disturbances) are used to estimate the disturbing potential using least-squares techniqu
Murad, P. A.
2003-01-01
Newtonian gravitation adequately predicts planet and satellite motion. Gravitational anomalies and the wish to travel at relativistic speeds, however, imply that gravity should be integrated within a unification framework that may include electricity and magnetism. Thus, new theories are needed that predict currently accepted phenomenon as well as anomalies to prepare the necessary groundwork for experimental validation needed for advanced technology propulsion schemes and far-term missions. A primary deficiency is that we are obviously limited within the confines of our own solar system and a different gravity model may be applicable elsewhere in the cosmos. The model proposed here follows previous ideas proposed by Murad, Dyatlov, and Jefimenko for a universal gravitation model with an intrinsic radial force term coupled with angular momentum. Including angular momentum may explain several spin symmetries seen in some anomalous gyroscopic experiments and throughout the universe regarding planets that orbit around the sun: moons that orbit larger planetary bodies: and the rotation about each planetary axis.
Windhari, Ayuty; Handayani, Gunawan
2015-04-01
The 3D inversion gravity anomaly to estimate topographical density using a matlab source code from gridded data provided by Parker Oldenburg algorithm based on fast Fourier transform was computed. We extend and improved the source code of 3DINVERT.M invented by Gomez Ortiz and Agarwal (2005) using the relationship between Fourier transform of the gravity anomaly and the sum of the Fourier transform from the topography density. We gave density contrast between the two media to apply the inversion. FFT routine was implemented to construct amplitude spectrum to the given mean depth. The results were presented as new graphics of inverted topography density, the gravity anomaly due to the inverted topography and the difference between the input gravity data and the computed ones. It terminates when the RMS error is lower than pre-assigned value used as convergence criterion or until maximum of iterations is reached. As an example, we used the matlab program on gravity data of Banten region, Indonesia.
Noncommutative Topological Theories of Gravity
García-Compéan, H; Ramírez, C; Sabido, M
2003-01-01
The possibility of noncommutative gravity arising in the same manner as Yang-Mills theory is explored. Using the Seiberg-Witten map we give a noncommutative version of topological gravity, from which the Euler characteristic and the signature are obtained, in both cases up to third order in the noncommutativity parameter. Finally, we discuss possible ways towards obtaining noncommutative gravitational instantons and to detect local and global gravitational anomalies within this context.
Simple recipe for holographic Weyl anomaly
Bugini, F
2016-01-01
We propose a recipe - arguably the simplest - to compute the holographic type-B Weyl anomaly for general higher-derivative gravity in asymptotically AdS spacetimes. In 5 and 7 dimensions we identify a suitable basis of curvature invariants that allows to read off easily, without any further computation, the Weyl anomaly coefficients of the dual CFT. We tabulate the contributions from quadratic, cubic and quartic purely algebraic curvature invariants and also from terms involving derivatives of the curvature. We provide few examples, where the anomaly coefficients have been obtained by other means, to illustrate the effectiveness of our prescription.
Rapp, Richard H.; Pavlis, Nikolaos
A method is presented for the estimation of a global gravity anomaly field using the combination of satellite-derived potential coefficient models and the coefficients implied by the Airy-Heiskanen topographic/isostatic potential (Rummel et al., 1988) from topographic models with a 30-km depth of compensation. Gravity anomalies calculated with this method are compared with a terrestrial 1 x 1 degree anomaly file where the anomaly standard deviations were less than 10 mgals. Using the GEM T1 model (Marsh et al., 1988) to degree 36, the rms anomaly discrepency was + or - 19 mgals, while the rms values for the terrestrial anomalies was + or - 28 mgals.
Radial and tangential gravity rates from GRACE in areas of glacial isostatic adjustment
van der Wal, Wouter; Kurtenbach, Enrico; Kusche, Jürgen; Vermeersen, Bert
2011-11-01
In areas dominated by Glacial Isostatic Adjustment (GIA), the free-air gravity anomaly rate can be converted to uplift rate to good approximation by using a simple spectral relation. We provide quantitative comparisons between gravity rates derived from monthly gravity field solutions (GFZ Potsdam, CSR Texas, IGG Bonn) from the Gravity Recovery and Climate Experiment (GRACE) satellite mission with uplift rates measured by GPS in these areas. The band-limited gravity data from the GRACE satellite mission can be brought to very good agreement with the point data from GPS by using scaling factors derived from a GIA model (the root-mean-square of differences is 0.55 mm yr-1 for a maximum uplift rate signal of 10 mm yr-1). The root-mean-square of the differences between GRACE derived uplift rates and GPS derived uplift rates decreases with increasing GRACE time period to a level below the uncertainty that is expected from GRACE observations, GPS measurements and the conversion from gravity rate to uplift rate. With the current length of time-series (more than 8 yr) applying filters and a hydrology correction to the GRACE data does not reduce the root-mean-square of differences significantly. The smallest root-mean-square was obtained with the GFZ solution in Fennoscandia and with the CSR solution in North America. With radial gravity rates in excellent agreement with GPS uplift rates, more information on the GIA process can be extracted from GRACE gravity field solutions in the form of tangential gravity rates, which are equivalent to a rate of change in the deflection of the vertical scaled by the magnitude of gravity rate vector. Tangential gravity rates derived from GRACE point towards the centre of the previously glaciated area, and are largest in a location close to the centre of the former ice sheet. Forward modelling showed that present day tangential gravity rates have maximum sensitivity between the centre and edge of the former ice sheet, while radial gravity
Regional magnetic anomaly constraints on continental rifting
Vonfrese, R. R. B.; Hinze, W. J.; Olivier, R.; Bentley, C. R.
1985-01-01
Radially polarized MAGSAT anomalies of North and South America, Europe, Africa, India, Australia and Antarctica demonstrate remarkably detailed correlation of regional magnetic lithospheric sources across rifted margins when plotted on a reconstruction of Pangea. These major magnetic features apparently preserve their integrity until a superimposed metamorphoric event alters the magnitude and pattern of the anomalies. The longevity of continental scale magnetic anomalies contrasts markedly with that of regional gravity anomalies which tend to reflect predominantly isostatic adjustments associated with neo-tectonism. First observed as a result of NASA's magnetic satellite programs, these anomalies provide new and fundamental constraints on the geologic evolution and dynamics of the continents and oceans. Accordingly, satellite magnetic observations provide a further tool for investigating continental drift to compliment other lines of evidence in paleoclimatology, paleontology, paleomagnetism, and studies of the radiometric ages and geometric fit of the continents.
Holographic entanglement entropy in Lovelock gravities
de Boer, J.; Kulaxizi, M.; Parnachev, A.
2011-01-01
We study entanglement entropies of simply connected surfaces in field theories dual to Lovelock gravities. We consider Gauss-Bonnet and cubic Lovelock gravities in detail. In the conformal case the logarithmic terms in the entanglement entropy are governed by the conformal anomalies of the CFT; we v
Geoid anomalies over Gorringe Ridge, North Atlantic Ocean
Souriau, A.
1984-04-01
The geoid anomalies over Gorringe Ridge, a very prominent high in the topography north of the Azores-Gibraltar plate boundary, have been deduced from Seasat alimetric data, and an interpretation of these anomalies together with the gravity anomalies is attempted. The geoid anomalies generated by the topographic high alone with the serpentinite density nearly fit the observed geoid anomalies, so that the structure must be either out of isostatic equilibrium or compensated at great depth. It is shown that a model in isostatic equilibrium with a small negative density contrast extending to 60 km depth or more explains both the gravity and geoid anomalies and is compatible with the deep seismicity north of Gorringe Ridge. Previous nonisostatic models, one involving an uplift of the upper mantle beneath the ridge, one describing a nascent subduction zone, and another involving flexure of the elastic part of the lithosphere due to the ridge loading, are discussed.
Bomfim, E. P.; Braitenberg, C.; Molina, E. C.
2013-11-01
The gravity observations of the satellite GOCE have a global homogeneous coverage and precision. This data set constitutes an independent new tool to control the quality of terrestrial gravity data. Terrestrial data reach higher resolution and precision, but can be affected by errors due to factors such as different vertical geodetic datums, wrong position in latitude and longitude, geodynamic effects and gravimeter drift, which tends to accumulate over long distances. Terrestrial data recover gravity signals at shorter wavelengths compared to the GOCE satellite, but the average gravity anomaly values can be compared to the GOCE derived values which are bandlimited to lower frequencies. We consider the area of the Amazon Craton, and in particular the Solimões, Amazon and Parnaiba Basins, and part of the Tocantins and São Francisco Provinces in Brazil, to estimate the systematic errors in terrestrial gravity data. We calculate the average terrestrial gravity anomaly by spatial averages applying Gaussian, inverse distance and simple averages, which allows to compare the long- and medium-wavelength part of the terrestrial gravity anomalies with the gravity field derived from GOCE. We also consider the combined satellite-terrestrial model EGM2008 up to degree and order 250 (i.e. maximum expansion from satellite GOCE). The results show that the systematic errors range from about -28.1 to 25.2 mGal with a standard deviation value of 6.4 mGal. The mean value over the study area is about zero, obtaining 0.27 mGal difference between the Gaussian average of the terrestrial gravity data and the gravity data from the GOCE satellite-only model and is smaller than the commission error associated to the geopotential model. Also, we verified that 64.8 per cent of the study area does not present systematic errors, as their difference is within the commission error of 5.1 mGal of the GOCE model in the harmonic expansion up to degree 250. The comparison of the terrestrial data with
Geopotential field anomalies and regional tectonic features
Mandea, Mioara; Korte, Monika
2016-07-01
Maps of both gravity and magnetic field anomalies offer crucial information about physical properties of the Earth's crust and upper mantle, required in understanding geological settings and tectonic structures. Density and magnetization represent independent rock properties and thus provide complementary information on compositional and structural changes. Two regions are considered: southern Africa (encompassing South Africa, Namibia and Botswana) and Germany. This twofold choice is motivated firstly by the fact that these regions represent rather diverse geological and geophysical conditions (old Archean crust with strong magnetic anomalies in southern Africa, and much younger, weakly magnetized crust in central Europe) and secondly by our intimate knowledge of the magnetic vector ground data from these two regions. We take also advantage of the recently developed satellite potential field models and compare magnetic and gravity gradient anomalies of some 200 km resolution. Comparing short and long wavelength anomalies and the correlation of rather large scale magnetic and gravity anomalies, and relating them to known lithospheric structures, we generally find a better agreement over the southern African region than the German territory. This probably indicates a stronger concordance between near-surface and deeper structures in the former area, which can be perceived to agree with a thicker lithosphere.
U.S. Terrain Corrected Free Air Anomalies (96)
National Oceanic and Atmospheric Administration, Department of Commerce — This 2' gravity anomaly grid for the conterminous United States is NOT the input data set used in development of the GEOID96 model. This gravity grid models the 1.7...
Anomaly Structure of Supergravity and Anomaly Cancellation
Butter, Daniel
2009-01-01
We display the full anomaly structure of supergravity, including new D-term contributions to the conformal anomaly. This expression has the super-Weyl and chiral U(1)_K transformation properties that are required for implementation of the Green-Schwarz mechanism for anomaly cancellation. We outline the procedure for full anomaly cancellation. Our results have implications for effective supergravity theories from the weakly coupled heterotic string theory.
Dishberger, Debra McLean
1983-04-01
This report represents a continuation of gravity work in the Cascade Mountains of Washington supported by the Division of Geology and Earth Resources since 1974. The purpose of this research has been collection of baseline gravity data for use in geothermal resource evaluation. Results of the Division's gravity studies to date are given in Danes and Phillips (1983a, 1983b). One of the problems encountered when analyzing gravity data is distinguishing between those parts of the data that represent geologic structures of interest, and those that do not. In many cases, the features of interest are relatively small, near-surface features, such as those sought in mineral, petroleum, or geothermal exploration. Gravity anomalies caused by such structures may be distorted or masked by anomalies caused by larger, deeper geologic structures. Gravity anomalies caused by relatively shallow, small geologic structures are termed residual anomalies. Those due to broad, deep-seated features can be described as regional anomalies. The purpose of this report is to describe a Fourier analysis method for separating residual and regional gravity anomalies from a complete Bouguer gravity anomaly field. The technique has been applied to gravity data from the Southern Cascade Mountains, Washington. Residual gravity anomaly maps at a scale of 1:250,000 are presented for various regional wavelength filters, and a power spectrum of the frequency components in the South Cascade gravity data is displayed. No attempt is made to interpret the results of this study in terms of geologic structures.
Lithospheric analysis of satellite geopotential anomalies of East Asia
Tan, Li
Satellite gravity and magnetic anomalies are used to study the lithosphere of East Asia. Free-air gravity anomalies are decomposed into terrain-correlated, mantle/core and intracrustal components by spectral correlation analysis of the free-air gravity anomalies and terrain gravity effects. Compensated terrain gravity anomalies are obtained by removing the terrain-correlated free-air gravity anomalies. They are used to estimate the Moho undulation and crustal thickness by Gauss-Legendre quadrature (GLQ) inversion techniques assuming a Airy-Heiskanen model of crustal compensation. These results are used to develop enhanced reduction procedures to generate an improved Magsat magnetic anomaly map for East Asia. A degree 12 core field is removed from the data that are updated for the crustal components in the core field differences between degree 14 and 12. These components are estimated by using spectral correlation analysis to compare the Magsat anomalies to the magnetic effect of the crust that is available from the first vertical derivative of the terrain-correlated free-air gravity anomalies via Poisson's theorem. External field effects are separated using pass-by-pass correlation analysis of the dusk and dawn data sets and their spectral reconstruction. Coherent components in the dusk and dawn maps are combined to estimate the magnetic anomalies of the lithosphere. Long wavelength magnetic features related to lower crustal thickness variations are converted into effective magnetization contrasts by a new GLQ inversion technique. Effective magnetization contrasts of the lower crust range over ±4 A/m in accordance petrological studies. Finally, a new GLQ integration formula for triangular wedge sources is derived for modeling of satellite-altitude geopotential field anomalies from arbitrarily shaped sources. Detailed magnetization and density contrasts for central India, the Tibetan Plateau, and the Bengal Gulf region are modeled by this new formula. Positive
Chiral Anomaly in Contorted Spacetimes
Mielke, E W
1999-01-01
The Dirac equation in Riemann-Cartan spacetimes with torsion is reconsidered. As is well-known, only the axial covector torsion $A$, a one-form, couples to massive Dirac fields. Using diagrammatic techniques, we show that besides the familiar Riemannian term only the Pontrjagin type four-form $dA\\wedge dA$ does arise additionally in the chiral anomaly, but not the Nieh-Yan term $d ^* A$, as has been claimed recently. Implications for cosmic strings in Einstein-Cartan theory as well as for Ashtekar's canonical approach to quantum gravity are discussed.
Kinkhabwala, Ali
2013-01-01
The most fundamental problem in statistics is the inference of an unknown probability distribution from a finite number of samples. For a specific observed data set, answers to the following questions would be desirable: (1) Estimation: Which candidate distribution provides the best fit to the observed data?, (2) Goodness-of-fit: How concordant is this distribution with the observed data?, and (3) Uncertainty: How concordant are other candidate distributions with the observed data? A simple unified approach for univariate data that addresses these traditionally distinct statistical notions is presented called "maximum fidelity". Maximum fidelity is a strict frequentist approach that is fundamentally based on model concordance with the observed data. The fidelity statistic is a general information measure based on the coordinate-independent cumulative distribution and critical yet previously neglected symmetry considerations. An approximation for the null distribution of the fidelity allows its direct conversi...
de Rham, Claudia
2014-01-01
We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali–Gabadadze–Porrati model (DGP...
Claudia de Rham
2016-01-01
We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali-Gabadadze-Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware-Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alt...
de Rham, Claudia
2014-01-01
We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali-Gabadadze-Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware-Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alt...
2014-01-01
We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali–Gabadadze–Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware–Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alt...
Bianchi, Eugenio
The following sections are included: * Introduction * Topological Field Theory and Gravity * Classical Spinfoam Gravity: Degrees of Freedom and Foams * Unitary Representations of the Rotation and the Lorentz Group * Boundary Variables and the Loop Quantum Gravity Hilbert Space * Spinfoam Partition Function and the Vertex Amplitude * Cellular Quantum Geometry: A Single Atom of Space * Cellular Quantum Geometry: Coherent Spin-networks * Vertex-amplitude Asymptotics and Regge Gravity * Reconstructing a Semiclassical Spacetime * Conclusions * References
Gravity evolution and earthquake activities of the northeastern edge of Qinghai-Xizang block
祝意青; 李辉; 朱桂芝; 徐云马
2004-01-01
The relationship between temporal-spatial evolution of gravity and earthquake activity during 1992～2001 has beenanalyzed systematically byintegrally adjusting the gravity observation data of the northeastern edge of Qinghai-Xizang (Qingzang) block. The result shows that the gravity observation data of the northeastern edge of Qingzangblock obtained by using the uniform starting datum can completely reflect the precursory gravity informationappearing during the seismogenic process. In the genesis stage of an earthquake, regional gravity anomaly appearsin a large area, resulting in related local gravity anomaly. The dynamic image of gravity field can clearly reflect theorderly evolution and earthquake activity.
Ajala, R. A.; Mann, P.
2016-12-01
We used gravity data constrained by deep-penetration seismic reflection lines to determine the crustal structure beneath the Mississippi delta, the seventh-largest deltaic accumulation on Earth. The observed gravity anomaly at the margin consist of a high of 50 mGal over the shelf with a low of -27 mGal at a landward distance of 250 km, a low of -18 mGal at a seaward distance of 136 km, and another high of 23 mGal at a seaward distance of 178 km from the shelf edge. The gravity high is centered over the thickest part of the delta, much of which has been deposited since the Miocene. The elastic thickness of the underlying crust is estimated by comparing the amplitude and wavelength of the observed gravity anomaly to the predicted anomaly based on simple elastic plate models. The process-oriented gravity modeling approach has been used to flexurally backstrip the sediments and add the present-day water depth to obtain the total tectonic subsidence (TTS). The gravity effect due to the initial rift structure obtained from the TTS known as the "rifting anomaly" and sediment loading called the "sedimentation anomaly" are used to compute the present-day gravity anomaly. The best fit result is for a margin which sediments were deposited on thinned transitional crust with an elastic thickness of 48 km. Results from flexural modeling show that top of basement has been flexed up to 8 km over a lateral distance of more than 500 km by the deltaic load. The map-view shape of the uplifted rim with a predicted, maximum topographic expression of 40 m is egg-shaped with its northern, more narrow tip crossing the Mississippi Valley near Memphis, its northwestern part running parallel to the northern Ouachita Mountains, its western part tracking parallel to the Mexia-Balcones fault system of Texas, and its eastern edge parallel to the west coast of Florida. While the overall magnitude of the topographic flexure is low, delta-related flexure may have contributed to the Miocene
Chiral anomalies and differential geometry
Zumino, B.
1983-10-01
Some properties of chiral anomalies are described from a geometric point of view. Topics include chiral anomalies and differential forms, transformation properties of the anomalies, identification and use of the anomalies, and normalization of the anomalies. 22 references. (WHK)
Gravity Analysis of the Jeffera Basin, Tunisia
Mickus, K.; Gabtni, H.; Jallouli, C.
2004-12-01
Southern Tunisia consists of two main tectonic provinces: 1) the Saharan Platform and 2) the folded Atlasic domain, separated by the North Saharan Flexure. The Saharan Platform, which contains the Ghadames Basin and the Telemzane Arch, consists of gently dipping Paleozoic strata overlain by Triassic to Cretaceous sediments. The Atlasic domain consists of a thicker sequence of mainly Mesozoic and younger rock with less complete sequences of Paleozoic strata. Within the Atlasic domain are the still actively subsiding Chotts and Jeffera basins. The Jeffera basin, which occurs to the east of the Telemzane Arch contains at least eight kilometers of Paleozoic and younger sediment that were formed during numerous subsidence episodes since Carboniferous time. The Jeffera basin is dominated by tilted fault blocks that were formed during numerous tectonic episodes. Several unpublished seismic reflection profiles and well data exist for the Jeffera basin, however a deep structural analysis of the basin has not been published. We examined the existing gravity data in conjunction with available well and geologic data to determine structural features within the basin. The Bouguer gravity anomaly map shows that the Jeffera basin is dominated by a narrow northwest-trending gravity minimum. However, a more detailed analysis consisting of wavelength filtering and edge enhancements indicate that the structure of the basin is more complicated than indicated by the Bouguer gravity anomaly map. A residual gravity anomaly map indicates that the Jeffera basin consists of at least three and maybe four subbasins. Additionally, the Jeffera Fault marks the boundary between northwest-trending gravity anomalies to its northeast and east-trending anomalies over the Saharan Platform. The above observation is amplified by the construction of the enhanced horizontal derivatives (EHG) of both the complete Bouguer gravity and the residual gravity anomaly maps. The EHG maps highlight the lateral
Three-Dimensional Gravity Model Applied to Underwater Navigation
YAN Lei; FENG Hao; DENG Zhongliang; GAO Zhengbing
2004-01-01
At present, new integrated navigation, which usesthe location function of reference gravity anomaly map to control the errors of the inertial navigation system (INS), has been developed in marine navigation. It is named the gravityaided INS. Both the INS and real-time computation of gravity anomalies need a 3-D marine normal gravity model.Conventionally, a reduction method applied in geophysical survey is directly introduced to observed data processing. This reduction does not separate anomaly from normal gravity in the observed data, so errors cannot be avoided. The 3-D marine normal gravity model was derived from the J2 gravity model, and is suitable for the region whose depth is less than 1000 m.
On the trace anomaly of a Weyl fermion
Bastianelli, Fiorenzo
2016-01-01
We calculate the trace anomaly of a Weyl fermion coupled to gravity by using Fujikawa's method supplemented by a consistent regulator. The latter is constructed out of Pauli-Villars regulating fields. The motivation for presenting such a calculation stems from recent studies that suggest that the trace anomaly of chiral fermions in four dimensions might contain an imaginary part proportional to the Pontryagin density. We find that the trace anomaly of a Weyl fermion is given by half the trace anomaly of a Dirac fermion, so that no imaginary part proportional to the Pontryagin density is seen to arise.
Bajracharya, S.; Sideris, M. G.
The use of (i) a proper gravimetric terrain reduction scheme for the interpolation of free-air (FA) gravity anomalies, (ii) actual Earth crust density information, and (iii) a high-resolution digital terrain model (DTM) for gravimetric terrain reduction are three important aspects in precise geoid computation using Helmert's second method of condensation, especially in areas of rugged topography. First, this paper illus- trates via a numerical test in the Canadian Rockies the effect different gravity reduc- tion schemes have on gravity interpolation and on Helmert geoid determination. The Bouguer and residual terrain modelling (RTM) topographic reductions, the Rudzki inversion scheme, and the topographic-isostatic reductions of Pratt-Hayford (PH) and Airy-Heiskanen (AH) are used to remove terrain effects before gridding FA anomalies, and then their corresponding topographic or topographic-isostatic effects are restored to produce FA anomalies. Our results show that the difference between FA anomalies interpolated directly and after applying topographic reductions can reach maximum values of 200 mGal, altering the geoid undulations by nearly 7 m maximum. The Helmert geoid undulations using Pratt-Hayford and RTM reductions in gravity inter- polation exhibit the best fit with GPS-levelling derived undulations in the test area, with the standard deviations of 28 cm for both of these techniques. Second, this paper shows the importance of using actual crust density information on Helmert geoid de- termination. This information, which is available as a two-dimensional digital density model (DDM) in the test area, is incorporated in all steps of the geoid computational process. The Faye anomalies, the absolute geoid undulation, and the indirect effect on geoid using constant crust density of 2.67 g/cm3 are compared with those using lateral density variation. Finally, the effect of using different DTM grid resolutions of 6", 15", 30", 45", 1' and 2' for Faye anomalies
Processing Marine Gravity Data Around Korea
Lee, Y.; Choi, K.; Kim, Y.; Ahn, Y.; Chang, M.
2008-12-01
In Korea currently 4 research ships are under operating in Korea, after the first research vessel equipped shipborne gravity meter was introduced in 1990s. These are Onnuri(launch 1991) of KORDI(Korea Ocean Research & Development Institute), Haeyang2000(launch 1996), Badaro1(launch 2002) of NORI(National Oceanographic Research Institute) and Tamhae2(launch 1997) of KIGAM(Korea Institute of Geoscience and Mineral Resources). Those of research vessel, Haeyang2000 have observed marine gravity data over 150,000 points each year from year 1996 to year 2003. Haeyang2000, about 2,500 tons, is unable to operate onshore so NORI has constructed another 600 tons research ship Badaro1 that has observed marine gravity data onshore since year 2002. Haeyang2000 finished observing marine gravity data offshore within Korean territorial waters until year 2003. Currently Badaro1 is observing marine gravity data onshore. These shipborne gravity data will be very useful and important on geodesy and geophysics research also those data can make a contribution to developing these studies. In this study NORI's shipbrne gravity data from 1996 to 2007 has been processed for fundamental data to compute Korean precise geoid. Marine gravity processing steps as followed. 1. Check the time sequence, latitude and longitude position, etc. of shipborne gravity data 2. Arrangement of the tide level below the pier and meter drift correction of each cruise. 3. Elimination of turning points. 4. The time lag correction. 5. Computation of RV's velocities, Heading angles and the Eötvös correction. 6. Kalman filtering of GPS navigation data using cross-over points. 7. Cross-over correction using least square adjustment. About 2,058,000 points have been processed with NORI's marine gravity data from 1996 to 2007 in this study. The distribution of free-air anomalies was -41.0 mgal to 136.0 mgal(mean 8.90mgal) within Korean territorial waters. The free-air anomalies processed with the marine gravity data are
Gravity survey of the southwestern part of the sourthern Utah geothermal belt
Green, R.T.; Cook, K.L.
1981-03-01
A gravity survey covering an area of 6200 km/sup 2/ was made over the southwestern part of the southern Utah geothermal belt. The objective of the gravity survey is to delineate the geologic structures and assist in the understanding of the geothermal potential of the area. A total of 726 new gravity stations together with 205 existing gravity stations, are reduced to give: (1) a complete Bouguer gravity anomaly map, and (2) a fourth-order residual gravity anomaly map; both maps have a 2-mgal contour interval. The complete Bouguer gravity anomaly map shows an east-trending regional gravity belt with a total relief of about 70 mgal which crosses the central portion of the survey area. The gravity belt is attributed to a crustal lateral density variation of 0.1 gm/cc from a depth of 5 to 15 km.
The gravity field of the U.S. Atlantic continental margin
Grow, A.J.; Bowin, C.O.; Hutchinson, D.O.
1979-01-01
Approximately 39,000 km of marine gravity data collected during 1975 and 1976 have been integrated with U.S. Navy and other available data over the U.S. Atlantic continental margin between Florida and Maine to obtain a 10 mgal contour free-air gravity anomaly map. A maximum typically ranging from 0 to +70 mgal occurs along the edge of the shelf and Blake Plateau, while a minimum typically ranging from -20 to -80 mgal occurs along the base of the continental slope, except for a -140 mgal minimum at the base of the Blake Escarpment. Although the maximum and minimum free-air gravity values are strongly influenced by continental slope topography and by the abrupt change in crustal thickness across the margin, the peaks and troughs in the anomalies terminate abruptly at discrete transverse zones along the margin. These zones appear to mark major NW-SE fractures in the subsided continental margin and adjacent deep ocean basin, which separate the margin into a series of segmented basins and platforms. Rapid differential subsidence of crustal blocks on either side of these fractures during the early stages after separation of North America and Africa (Jurassic and Early Cretaceous) is inferred to be the cause of most of the gravity transitions along the length of margin. The major transverse zones are southeast of Charleston, east of Cape Hatteras, near Norfolk Canyon, off Delaware Bay, just south of Hudson Canyon and south of Cape Cod. Local Airy isostatic anomaly profiles (two-dimensional, without sediment corrections) were computed along eight multichannel seismic profiles. The isostatic anomaly values over major basins beneath the shelf and rise are generally between -10 and -30 mgal while those over the platform areas are typically 0 to +20 mgal. While a few isostatic anomaly profiles show local 10-20 mgal increases seaward of the East Coast Magnetic Anomaly (ECMA: inferred to mark the ocean-continent boundary), the lack of a consistent correlation indicates that the
Anomaly mediation in superstring theory
Conlon, J.P. [Rudolf Peierls Center for Theoretical Physics, 1 Keble Road, Oxford, OX1 3NP (United Kingdom); Balliol College, Oxford, OX1 3BJ (United Kingdom); Kavli Institute of Theoretical Physics, Kohn Hall, University of California, Santa Barbara CA 93106-4030 (United States); Goodsell, M. [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22603 Hamburg (Germany); Palti, E. [Centre de Physique Theorique, Ecole Polytechnique, CNRS, 91128 Palaiseau (France)
2011-01-15
We study anomaly mediated supersymmetry breaking in type IIB string theory and use our results to test the supergravity formula for anomaly mediated gaugino masses. We compute 1-loop gaugino masses for models of D3-branes on orbifold singularities with 3-form fluxes by calculating the annulus correlator of 3-form flux and two gauginos in the zero momentum limit. Consistent with supergravity expectations we find both anomalous and running contributions to 1-loop gaugino masses. For background Neveu-Schwarz H-flux we find an exact match with the supergravity formula. For Ramond-Ramond flux there is an off-shell ambiguity that precludes a full matching. The anomaly mediated gaugino masses, while determined by the infrared spectrum, arise from an explicit sum over UV open string winding modes. We also calculate brane-to-brane tree-level gravity mediated gaugino masses and show that there are two contributions coming from the dilaton and from the twisted modes, which are suppressed by the full T{sup 6} volume and the untwisted T{sup 2} volume respectively. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Anomaly mediation in superstring theory
Conlon, Joseph P. [Rudolf Peierls Center for Theoretical Physics, Oxford (United Kingdom); Balliol College, Oxford (United Kingdom); Goodsell, Mark [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Palti, Eran [Centre de Physique Theoretique, Ecole Polytechnique, CNRS, Palaiseau (France)
2010-08-15
We study anomaly mediated supersymmetry breaking in type IIB string theory and use our results to test the supergravity formula for anomaly mediated gaugino masses. We compute 1-loop gaugino masses for models of D3-branes on orbifold singularities with 3-form fluxes by calculating the annulus correlator of 3-form flux and two gauginos in the zero momentum limit. Consistent with supergravity expectations we find both anomalous and running contributions to 1-loop gaugino masses. For background Neveu-Schwarz H-flux we find an exact match with the supergravity formula. For Ramond-Ramond flux there is an off-shell ambiguity that precludes a full matching. The anomaly mediated gaugino masses, while determined by the infrared spectrum, arise from an explicit sum over UV open string winding modes. We also calculate brane-to-brane tree-level gravity mediated gaugino masses and show that there are two contributions coming from the dilaton and from the twisted modes, which are suppressed by the full T{sup 6} volume and the untwisted T{sup 2} volume respectively. (orig.)
Antarctic marine gravity field from high-density satellite altimetry
Sandwell, David T.
1992-01-01
High-density (about 2-km profile spacing) Geosat/GM altimetry profiles were obtained for Antarctic waters (6-deg S to 72 deg S) and converted to vertical gravity gradient, using Laplace's equation to directly calculate gravity gradient from vertical deflection grids and Fourier analysis to construct gravity anomalies from two vertical deflection grids. The resultant gravity grids have resolution and accuracy comparable to shipboard gravity profiles. The obtained gravity maps display many interesting and previously uncharted features, such as a propagating rift wake and a large 'leaky transform' along the Pacific-Antarctic Rise.
Gravity Aided Navigation Precise Algorithm with Gauss Spline Interpolation
WEN Chaobin
2015-01-01
Full Text Available The gravity compensation of error equation thoroughly should be solved before the study on gravity aided navigation with high precision. A gravity aided navigation model construction algorithm based on research the algorithm to approximate local grid gravity anomaly filed with the 2D Gauss spline interpolation is proposed. Gravity disturbance vector, standard gravity value error and Eotvos effect are all compensated in this precision model. The experiment result shows that positioning accuracy is raised by 1 times, the attitude and velocity accuracy is raised by 1～2 times and the positional error is maintained from 100~200 m.
Empirical Foundations of Relativistic Gravity
Ni, W T
2005-01-01
In 1859, Le Verrier discovered the mercury perihelion advance anomaly. This anomaly turned out to be the first relativistic-gravity effect observed. During the 141 years to 2000, the precisions of laboratory and space experiments, and astrophysical and cosmological observations on relativistic gravity have been improved by 3 orders of magnitude. In 1999, we envisaged a 3-6 order improvement in the next 30 years in all directions of tests of relativistic gravity. In 2000, the interferometric gravitational wave detectors began their runs to accumulate data. In 2003, the measurement of relativistic Shapiro time-delay of the Cassini spacecraft determined the relativistic-gravity parameter gammaγ with a 1.5-order improvement. In October 2004, Ciufolini and Pavlis reported a measurement of the Lense-Thirring effect on the LAGEOS and LAGEOS2 satellites to 10 percent of the value predicted by general relativity. In April 2004, Gravity Probe B was launched and has been accumulating science data for more than ...
Anomaly of the Lense-Thirring precession in Kerr-Taub-NUT spacetimes
Chakraborty, Chandrachur
2014-01-01
Exact Lense-Thirring (LT) precession in Kerr-Taub-NUT spacetime is reviewed. It is shown that the LT precession does not obey the general inverse cube law of distance at strong gravity regime in Kerr-Taub-NUT spacetime. Rather, it becomes maximum just near the horizon, falls sharply and becomes negligibly small near the horizon. The precession rate increases again and after that it falls obeying the general inverse cube law of distance. This anomaly is maximum at the polar region of this spacetime and it vanishes after crossing a certain `critical' angle towards equator from pole. In addition, we show that if the Kerr-Taub-NUT spacetime rotates with the angular momentum $J=Mn$ (Mass$\\times$Dual Mass), one horizon disappears and only {\\it event horizon} exists at the distance $r=2M$.
Gravity Effects of Solar Eclipse and Inducted Gravitational Field
Tang, K.; Wang, Q.; Zhang, H.; Hua, C.; Peng, F.; Hu, K.
2003-12-01
During solar eclipses in recent decades, gravity anomalies were observed and difficult to be explained by Newton's gravitational theory. During the solar eclipse of 1995, India scientists Mishra et al. recorded a gravity valley in amplitude of 12 μ Gal; they interpreted that qualitatively as atmospheric effects. During the total solar eclipse of March 1997, we conducted a comprehensive geophysical observation at Mohe geophysical observatory of China (with latitude of 53.490 N and longitude of 122.340 E. From the data we recorded, we found two valleys about 5 to 7 μ Gal. Unnikrishnan et al. inferred this gravity anomaly was caused by the environment changes. We know that the observation had been conducting in a room inside a small building with a stable coal heating system; the temperature variation inside the experimental room was less 10C during the eclipse. Moreover, the measured atmospheric pressure change was less 1hPa during the eclipse. It is reasonable to believe that surrounding environment of the observatory excluded the significant gravity variations caused by temperature, pressure variation and local moving of persons and vehicles. To further study the gravity effects related to solar eclipses, our scientific team took more observations during Zambia total solar eclipse of June 2001 and Australia total solar eclipse of December 2002. After data corrections, we found respectively two gravity anomalies, with 3 to 4μ Gal for Zambia eclipse and 1.5μ Gal for Australia eclipse. As many scientists have pointed out that pressure-gravity factor is lower than 0.3μ Gal/hPa, it means that any gravity anomaly great than 0.5μ Gal could not be inferred as the results of atmospheric pressure change. The two more gravity anomalies recorded during the solar eclipses provided us strong evidences that some gravity anomalies could not simply be inferred as atmospheric pressure change. We have tried to explain those anomalies by the induced gravitational field.
Tracheobronchial Branching Anomalies
Hong, Min Ji; Kim, Young Tong; Jou, Sung Shick [Soonchunhyang University, Cheonan Hospital, Cheonan (Korea, Republic of); Park, A Young [Soonchunhyang University College of Medicine, Asan (Korea, Republic of)
2010-04-15
There are various congenital anomalies with respect to the number, length, diameter, and location of tracheobronchial branching patterns. The tracheobronchial anomalies are classified into two groups. The first one, anomalies of division, includes tracheal bronchus, cardiac bronchus, tracheal diverticulum, pulmonary isomerism, and minor variations. The second one, dysmorphic lung, includes lung agenesis-hypoplasia complex and lobar agenesis-aplasia complex
Healey, D.L. [Geological Survey, Denver, CO (USA)
1983-12-31
A large density contrast exists between the Paleozoic rocks (including the rocks of Climax stock) and less dense, Tertiary volcanic rocks and alluvium. This density contrast ranges widely, and herein for interpretive purposes, is assumed to average 0.85 Mg/m{sup 3} (megagrams per cubic meter). The large density contrast makes the gravity method a useful tool with which to study the interface between these rock types. However, little or no density contrast is discernible between the sedimentary Paleozoic rocks that surround the Climax stock and the intrusive rocks of the stock itself. Therefore the gravity method can not be used to define the configuration of the stock. Gravity highs coincide with outcrops of the dense Paleozoic rocks, and gravity lows overlie less-dense Tertiary volcanic rocks and Quaternary alluvium. The positions of three major faults (Boundary, Yucca, and Butte faults) are defined by steep gravity gradients. West of the Climax stock, the Tippinip fault has juxtaposed Paleozoic rocks of similar density, and consequently, has no expression in the gravity data in that area. The gravity station spacing, across Oak Spring Butte, is not sufficient to adequately define any gravity expression of the Tippinip fault. 18 refs., 5 figs.
Mashhoon, Bahram
2017-01-01
Relativity theory is based on a postulate of locality, which means that the past history of the observer is not directly taken into account. This book argues that the past history should be taken into account. In this way, nonlocality---in the sense of history dependence---is introduced into relativity theory. The deep connection between inertia and gravitation suggests that gravity could be nonlocal, and in nonlocal gravity the fading gravitational memory of past events must then be taken into account. Along this line of thought, a classical nonlocal generalization of Einstein's theory of gravitation has recently been developed. A significant consequence of this theory is that the nonlocal aspect of gravity appears to simulate dark matter. According to nonlocal gravity theory, what astronomers attribute to dark matter should instead be due to the nonlocality of gravitation. Nonlocality dominates on the scale of galaxies and beyond. Memory fades with time; therefore, the nonlocal aspect of gravity becomes wea...
GEOSAT44: High-Accuracy, High-Resolution Gravity
National Oceanic and Atmospheric Administration, Department of Commerce — This satellite altimeter data base contains precise geoid and gravity anomaly profiles which were constructed from the average of 44 repeat cycles of Geosat. The...
GEOSAT 44: High-Accuracy, High-Resolution Gravity
National Oceanic and Atmospheric Administration, Department of Commerce — This satellite altimeter data base contains precise geoid and gravity anomaly profiles which were constructed from the average of 44 repeat cycles of Geosat. The...
Weyl Anomaly and Initial Singularity Crossing
Awad, Adel
2015-01-01
We consider the role of quantum effects, mainly, Weyl anomaly in modifying FLRW model singular behavior at early times. Weyl anomaly corrections to FLRW models have been considered in the past, here we reconsider this model and show the following: The singularity of this model is weak according to Tipler and Krolak, therefore, the spacetime might admit a geodesic extension. Weyl anomaly corrections changes the nature of the initial singularity from a big bang singularity to a sudden singularity. The two branches of solutions consistent with the semiclassical treatment form a disconnected manifold. Joining these two parts at the singularity provides us with a $C^1$ extension to nonspacelike geodesics and leaves the spacetime geodesically complete. Using Gauss-Codazzi equations one can derive generalized junction conditions for this higher-derivative gravity. The extended spacetime obeys Friedmann and Raychaudhuri equations and the junction conditions. The junction does not generate Dirac delta functions in mat...
Determination of Antarctic geoid by using global gravity field
无
2000-01-01
With Chinese latest global gravity field model WDM94, the authors providethe geoid height and mean free-air gravity anomaly of Antarctica (The range of latitude is from—60° to—90°). In order to conclude and analyze the characters of Antarctic geoid roundly, the authors collect the latest oversea global gravity field model OSU91 (to degree and order 360) and JGMOSU (to degree and order 360), get the corresponding geoid height and mean free-air gravity anomaly. The results arecompared with the results got from WDM94, thus we get the difference. The standard deviation of geoid height between WDM94 and OSU91 is ± 1.90 re;the deviation of geoid between WDM9 and JGMOSU is ± 2.09 m. The standard deviation of mean gravity anomaly are±8.97 mGal and ± 9.32 mGal respectively.
Ensemble Averaged Gravity Theory
Khosravi, Nima
2016-01-01
We put forward the idea that all the theoretically consistent models of gravity have a contribution to the observed gravity interaction. In this formulation each model comes with its own Euclidean path integral weight where general relativity (GR) automatically has the maximum weight in high-curvature regions. We employ this idea in the framework of Lovelock models and show that in four dimensions the result is a specific form of $f(R,G)$ model. This specific $f(R,G)$ satisfies the stability conditions and has self-accelerating solution. Our model is consistent with the local tests of gravity since its behavior is same as GR for high-curvature regimes. In low-curvature regime the gravity force is weaker than GR which can interpret as existence of a repulsive fifth force for very large scales. Interestingly there is an intermediate-curvature regime where the gravity force is stronger in our model than GR. The different behavior of our model in comparison with GR in both low- and intermediate-curvature regimes ...
Gravity, geoid and the oceanic lithosphere
Watts, A. B.
1985-01-01
Plate tectonics and its contribution to progress in studies of the Earth's gravitational field is discussed. In acquisition, the development of forced feedback accelerometers, satellite navigation, and satellite radar altimetry significantly improved the accuracy and coverage of gravity data over the oceans. In interpretation, gravity and geoid anomalies are used to determine information on the thermal and mechanical properties of the oceanic lithosphere and the forces that drive plate motions.
Under the Volcano: Gravity Evidence for an Extinct Magma Chamber Beneath Syrtis Major, Mars
Kiefer, W. S.
2002-12-01
Syrtis Major is a Hesperian age shield volcano on Mars, 1100 km in diameter and just 1 km high. Two calderas, Meroe Patera and Nili Patera, are set within a broader topographic summit depression. The regional gravity field is well modeled by flexural support of the surface topography. For a crustal density of 2800 kg m-3 and a mantle density of 3400 kg m-3, the best fit elastic lithosphere thickness is 10 to 15 km. Increasing the crustal density requires a decrease in the lithospheric thickness. There is a pronounced free-air gravity anomaly over the summit caldera complex. This gravity high has an amplitude of 100 mGal through spherical harmonic degree 40 and 124 mGal through spherical harmonic degree 50 and is thus robustly determined by the Doppler tracking data from Mars Global Surveyor. The anomaly has a high degree of axial symmetry, with a low amplitude extension to the south. The gravity high occurs over the caldera's topographic low and thus requires the presence of dense material in the subsurface. The spatial association between the caldera and the buried mass anomaly suggests that the subsurface structure is due to the accumulation of dense igneous cumulates in a now solidified magma chamber. Because of the symmetry of the observed anomaly, it is modeled as a buried vertical cylinder in order to minimize the number of free parameters that must be constrained. The width of the observed anomaly constrains the cylinder radius to a maximum of 150 km. Assuming that the intrusive body is olivine similar to the martian meteorite Chassigny (Fo68, density 3500 kg m-3), the intrusive body has a minimum thickness of 5 km. A pyroxene rich intrusive, similar to the martian meteorite Nakhla, would have a lower density and thus a greater minimum thickness. The total mass anomaly is between 1.8-2.7 ṡ 1017 kg. This constitutes only 5-10% of the total mass of the volcano and its subsurface root. Thus, generating the required amount of cumulate minerals is probably not
Testing the Flyby Anomaly with the GNSS Constellation
Bertolami, O; Gil, P J S; Páramos, J
2012-01-01
We propose the concept of a space mission to probe the so called flyby anomaly, an unexpected velocity change experienced by some deep-space probes using earth gravity assists. The key feature of this proposal is the use of GNSS systems to obtain an increased accuracy in the tracking of the approaching spacecraft, mainly near the perigee. Two low-cost options are also discussed to further test this anomaly: an add-on to an existing spacecraft and a dedicated mission.
Elevation Difference and Bouguer Anomaly Analysis Tool (EDBAAT) User's Guide
Smittle, Aaron M.; Shoberg, Thomas G.
2017-06-16
This report describes a software tool that imports gravity anomaly point data from the Gravity Database of the United States (GDUS) of the National Geospatial-Intelligence Agency and University of Texas at El Paso along with elevation data from The National Map (TNM) of the U.S. Geological Survey that lie within a user-specified geographic area of interest. Further, the tool integrates these two sets of data spatially and analyzes the consistency of the elevation of each gravity station from the GDUS with TNM elevation data; it also evaluates the consistency of gravity anomaly data within the GDUS data repository. The tool bins the GDUS data based on user-defined criteria of elevation misfit between the GDUS and TNM elevation data. It also provides users with a list of points from the GDUS data, which have Bouguer anomaly values that are considered outliers (two standard deviations or greater) with respect to other nearby GDUS anomaly data. “Nearby” can be defined by the user at time of execution. These outputs should allow users to quickly and efficiently choose which points from the GDUS would be most useful in reconnaissance studies or in augmenting and extending the range of individual gravity studies.
Clément, Gilles
2007-01-01
Protecting the health, safety, and performance of exploration-class mission crews against the physiological deconditioning resulting from long-term weightlessness during transit and long-term reduced gravity during surface operations will require effective, multi-system countermeasures. Artificial gravity, which would replace terrestrial gravity with inertial forces generated by rotating the transit vehicle or by short-radius human centrifuge devices within the transit vehicle or surface habitat, has long been considered a potential solution. However, despite its attractiveness as an efficient
Lujan, Richard E.
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.
Off-level corrections for gravity meters
Niebauer, T. M.; Blitz, Thomas; Constantino, Andy
2016-04-01
Gravity meters must be aligned with the local gravity at any location on the surface of the earth in order to measure the full amplitude of the gravity vector. The gravitational force on the sensitive component of the gravity meter decreases by the cosine of the angle between the measurement axis and the local gravity vector. Most gravity meters incorporate two horizontal orthogonal levels to orient the gravity meter for a maximum gravity reading. In order to calculate a gravity correction it is often necessary to estimate the overall angular deviation between the gravity meter and the local gravity vector using two measured horizontal tilt meters. Typically this is done assuming that the two horizontal angles are independent and that the product of the cosines of the horizontal tilts is equivalent to the cosine of the overall deviation. These approximations, however, break down at large angles. This paper derives analytic formulae to transform angles measured by two orthogonal tilt meters into the vertical deviation of the third orthogonal axis. The equations can be used to calibrate the tilt sensors attached to the gravity meter or provide a correction for a gravity meter used in an off-of-level condition.
Girolami, Chiara; Rinaldo Barchi, Massimiliano; Pauselli, Cristina; Heyde, Ingo
2016-04-01
We analyzed the Bouguer gravity anomaly signal beneath the Mt. Amiata area in order to reconstruct the subsurface setting. The study area is characterized by a pronounced gravity minimum, possibly correlated with the observed anomalous heat flow and hydrothermal activity. Using different approaches, previous authors defined a low density body (generally interpreted as a magmatic intrusion) beneath this area, which could explain the observed gravity anomaly minimum. However the proposed geologic models show different geometries and densities for the batholith. The gravity data used in this study (kindly provided by eni) were acquired from different institutions (eni, OGS, USDMA and Servizio Geologico d'Italia) and collected in a unique dataset, consisting of about 50000 stations, randomly distributed, which cover Central Italy, with a spacing of less than 1 km. For each station the elevation and the Bouguer gravity anomaly data are given. From this dataset, we created two maps of the Bouguer gravity anomaly and the topography, using the Minimum Curvature gridding method considering a grid cell size of 500m x 500m. The Bouguer gravity anomaly has been computed using a density of 2.67 g/cm3. From these maps we extracted a window of about 240 km2 (12x20 km) for the study area, which includes the Mt. Amiata region and the adjacent Radicofani sedimentary basin. The first part of this study was focused on calculating the first order vertical derivative and the power spectra analysis of the Bouguer gravity anomaly to enhance the effect of shallow bodies and estimating the source depth respectively. The second part of this study was focused on constructing a 3D geological density model of the subsurface setting of the studied area, implementing a forward modelling approach. The stratigraphy of the study area's upper crust schematically consists of six litho-mechanical units, whose density was derived from velocity data collected by active seismic surveys. A preliminary
Fritts, David
1987-02-01
Gravity waves contributed to the establishment of the thermal structure, small scale (80 to 100 km) fluctuations in velocity (50 to 80 m/sec) and density (20 to 30%, 0 to peak). Dominant gravity wave spectrum in the middle atmosphere: x-scale, less than 100 km; z-scale, greater than 10 km; t-scale, less than 2 hr. Theorists are beginning to understand middle atmosphere motions. There are two classes: Planetary waves and equatorial motions, gravity waves and tidal motions. The former give rise to variability at large scales, which may alter apparent mean structure. Effects include density and velocity fluctuations, induced mean motions, and stratospheric warmings which lead to the breakup of the polar vortex and cooling of the mesosphere. On this scale are also equatorial quasi-biennial and semi-annual oscillations. Gravity wave and tidal motions produce large rms fluctuations in density and velocity. The magnitude of the density fluctuations compared to the mean density is of the order of the vertical wavelength, which grows with height. Relative density fluctuations are less than, or of the order of 30% below the mesopause. Such motions may cause significant and variable convection, and wind shear. There is a strong seasonal variation in gravity wave amplitude. Additional observations are needed to address and quantify mean and fluctuation statistics of both density and mean velocity, variability of the mean and fluctuations, and to identify dominant gravity wave scales and sources as well as causes of variability, both temporal and geographic.
1-deg x 1-deg Terrestrial Mean Free-Air Anomalies
National Oceanic and Atmospheric Administration, Department of Commerce — The 1x1 degree Terrestrial Mean Free-Air Gravity Anomaly and Geoid Undulations Data Base was compiled and developed by the Ohio State University. This data base was...
30-min x 30-min Terrestrial Mean Free-Air Anomalies
National Oceanic and Atmospheric Administration, Department of Commerce — The 30-min x 30-min Terrestrial Mean Free-Air Gravity Anomaly and Geoid Undulations Data Base was compiled and developed by the Ohio State University. This data base...
Accuracy Analysis for SST Gravity Field Model in China
LUO Jia; LUO Zhicai; ZOU Xiancai; WANG Haihong
2006-01-01
Taking China as the region for test, the potential of the new satellite gravity technique, satellite-to-satellite tracking for improving the accuracy of regional gravity field model is studied. With WDM94 as reference, the gravity anomaly residuals of three models, the latest two GRACE global gravity field model (EIGEN_GRACE02S, GGM02S) and EGM96, are computed and compared. The causes for the differences among the residuals of the three models are discussed. The comparison between the residuals shows that in the selected region, EIGEN_GRACE02S or GGM02S is better than EGM96 in lower degree part (less than 110 degree). Additionally, through the analysis of the model gravity anomaly residuals, it is found that some systematic errors with periodical properties exist in the higher degree part of EIGEN and GGM models, the results can also be taken as references in the validation of the SST gravity data.
Olesen, Arne Vestergaard; Andersen, Ole Baltazar; Tscherning, C.C.
2002-01-01
The National Survey and Cadastre - Denmark (KMS) has for several years produced gravity anomaly maps over the oceans derived from satellite altimetry. During the last four years, KMS has also conducted airborne gravity surveys along the coast of Greenland dedicated to complement the existing onsh...
Updated Hungarian Gravity Field Solution Based on Fifth Generation GOCE Gravity Field Models
Toth, Gyula; Foldvary, Lorant
2015-03-01
With the completion of the ESA's GOCE satellite's mission fifth generation gravity field models are available from the ESA's GOCE High Processing Facility. Our contribution is an updated gravity field solution for Hungary using the latest DIR R05 GOCE gravity field model. The solution methodology is least squares gravity field parameter estimation using Spherical Radial Base Functions (SRBF). Regional datasets include deflections of the vertical (DOV), gravity anomalies and quasigeoid heights by GPS/levelling. The GOCE DIR R05 model has been combined with the EGM20008 model and has been evaluated in comparison with the EGM2008 and EIGEN-6C3stat models to assess the performance of our regional gravity field solution.
Comparison of machine learning models for classification of BGP anomalies
2012-01-01
Worms such as Slammer, Nimda, and Code Red~I are anomalies that affect performance of the global Internet Border Gateway Protocol (BGP). BGP anomalies also include Internet Protocol (IP) prefix hijacks, miss-configurations, and electrical failures. In this Thesis, we analyzed the feature selection process to choose the most correlated features for an anomaly class. We compare the Fisher, minimum redundancy maximum relevance (mRMR), odds ratio (OR), extended/multi-class/weighted odds ratio (EO...
Geological Mapping of Sabah, Malaysia, Using Airborne Gravity Survey
Fauzi Nordin, Ahmad; Jamil, Hassan; Noor Isa, Mohd;
2016-01-01
using airborne gravity surveys. Airborne gravity data over land areas of Sabah has been combined with the marine airborne gravity data to provide a seamless land-to-sea gravity field coverage in order to produce the geological mapping. Free-air and Bouguer anomaly maps (density 2.67 g/cm3) have been......Airborne gravimetry is an effective tool for mapping local gravity fields using a combination of airborne sensors, aircraft and positioning systems. It is suitable for gravity surveys over difficult terrains and areas mixed with land and ocean. This paper describes the geological mapping of Sabah...... gravity data were 5-6 km. The airborne gravity survey database for landand marine areas has been compiled using ArcGIS geodatabase format in order to produce the update geological map of Sabah....
Gravity field determination and error assessment techniques
Yuan, D. N.; Shum, C. K.; Tapley, B. D.
1989-01-01
Linear estimation theory, along with a new technique to compute relative data weights, was applied to the determination of the Earth's geopotential field and other geophysical model parameters using a combination of satellite ground-based tracking data, satellite altimetry data, and the surface gravimetry data. The relative data weights for the inhomogeneous data sets are estimated simultaneously with the gravity field and other geophysical and orbit parameters in a least squares approach to produce the University of Texas gravity field models. New techniques to perform calibration of the formal covariance matrix for the geopotential solution were developed to obtain a reliable gravity field error estimate. Different techniques, which include orbit residual analysis, surface gravity anomaly residual analysis, subset gravity solution comparisons and consider covariance analysis, were applied to investigate the reliability of the calibration.
Quantisation deforms w∞ to W∞ gravity
Bergshoeff, E.; Howe, P.S.; Pope, C.N.; Sezgin, E.; Shen, X.; Stelle, K.S.
1991-01-01
Quantising a classical theory of w∞ gravity requires the introduction of an infinite number of counterterms in order to remove matter-dependent anomalies. We show that these counterterms correspond precisely to a renormalisation of the classical w∞ currents to quantum W∞ currents.
Competing Orders and Anomalies
Moon, Eun-Gook
2016-08-01
A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed.
Kobakhidze, A
2004-01-01
We propose a new mechanism for dynamical generation of the observed baryon asymmetry within the minimal Standard model extended by massive Majorana neutrinos and non-vanishing electroweak Chern-Simons term. We show that electroweak Chern-Simons number is produced in the expanding universe due to the conformal anomaly and subsequently converted into baryon number through the triangle anomaly.
Competing Orders and Anomalies.
Moon, Eun-Gook
2016-08-08
A conservation law is one of the most fundamental properties in nature, but a certain class of conservation "laws" could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the 't Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed.
Celada, Mariano; Montesinos, Merced
2016-01-01
$BF$ gravity comprises all the formulations of gravity that are based on deformations of $BF$ theory. Such deformations consist of either constraints or potential terms added to the topological $BF$ action that turn some of the gauge degrees of freedom into physical ones, particularly giving rise to general relativity. The $BF$ formulations have provided new and deep insights into many classical and quantum aspects of the gravitational field, setting the foundations for the approach to quantum gravity known as spinfoam models. In this review, we present a self-contained and unified treatment of the $BF$ formulations of $D$-dimensional general relativity and other related models, focusing on the classical aspects of them and including some new results.
Kiefer, Claus
2012-01-01
The search for a quantum theory of the gravitational field is one of the great open problems in theoretical physics. This book presents a self-contained discussion of the concepts, methods and applications that can be expected in such a theory. The two main approaches to its construction - the direct quantisation of Einstein's general theory of relativity and string theory - are covered. Whereas the first attempts to construct a viable theory for the gravitational field alone, string theory assumes that a quantum theory of gravity will be achieved only through a unification of all the interactions. However, both employ the general method of quantization of constrained systems, which is described together with illustrative examples relevant for quantum gravity. There is a detailed presentation of the main approaches employed in quantum general relativity: path-integral quantization, the background-field method and canonical quantum gravity in the metric, connection and loop formulations. The discussion of stri...
Celada, Mariano; González, Diego; Montesinos, Merced
2016-11-01
BF gravity comprises all the formulations of gravity that are based on deformations of BF theory. Such deformations consist of either constraints or potential terms added to the topological BF action that turn some of the gauge degrees of freedom into physical ones, particularly giving rise to general relativity. The BF formulations have provided new and deep insights into many classical and quantum aspects of the gravitational field, setting the foundations for the approach to quantum gravity known as spinfoam models. In this review, we present a self-contained and unified treatment of the BF formulations of D-dimensional general relativity and other related models, focusing on the classical aspects of them and including some new results.
Pipinos, Savas
2010-01-01
This article describes one classroom activity in which the author simulates the Newtonian gravity, and employs the Euclidean Geometry with the use of new technologies (NT). The prerequisites for this activity were some knowledge of the formulae for a particle free fall in Physics and most certainly, a good understanding of the notion of similarity…
Pipinos, Savas
2010-01-01
This article describes one classroom activity in which the author simulates the Newtonian gravity, and employs the Euclidean Geometry with the use of new technologies (NT). The prerequisites for this activity were some knowledge of the formulae for a particle free fall in Physics and most certainly, a good understanding of the notion of similarity…
Explaining the thick crust in Paraná basin, Brazil, with satellite GOCE gravity observations
Mariani, Patrizia; Braitenberg, Carla; Ussami, Naomi
2013-08-01
Seismologic observations in the last decades have shown that the crustal thickness in Paraná basin locally is over 40 km thick, which is a greater value than expected by the simple isostatic model considering the topographic load. The goal of this work is to explain this apparent discrepancy by modeling the internal crustal density anomalies through the gravity field. We use the latest Earth Gravity Model derived from the observations of the GOCE satellite mission, to retrieve the gravity anomaly and correct it for topographic effects, thus obtaining the Bouguer field. We then model the gravity effect of known stratigraphic units and of the seismological crustal thickness. The large Paraná basin comprises over 3500 m of Paleozoic sedimentary sequence with density between 2400 and 2600 kg/m3. During the Early Cretaceous the same basin was affected by a large amount of igneous activity with a volume of over 0.1 Mkm3. The flood basalt volcanism is known as the Serra Geral Formation, and has a maximum thickness of 1500 m. The stratigraphic units of the basin are topped by post-volcanic deposits of the Bauru Group, of about 300 m thickness, located in the northern part of the basin. The density and thickness of the sedimentary sequence are constrained by sonic logs of drill-holes and exploration seismic. We use the crustal thickness estimated from the newest seismological results for South America to calculate its gravity effect. Further we model the isostatic crustal thickness variation, allowing the comparison between a seismological Moho, an isostatic Moho, and a gravity-based Moho. We find that there is a clear positive Bouguer residual anomaly located in the northern and southern part of the Paraná basin, indicating the presence of a hidden mass, not considered up to now. We propose a model that explains this mass as magmatic rock, probably gabbro in lower crust, with density contrast of 200 kg/m3 and thickness of more than 10 km, thus demonstrating that the
Antarctic Crustal Thickness from Gravity Inversion
Vaughan, A. P.; Kusznir, N. J.; Ferraccioli, F.; Jordan, T. A.
2013-12-01
Using gravity anomaly inversion, we have produced the first comprehensive regional maps of crustal thickness and oceanic lithosphere distribution for Antarctica and the Southern Ocean. We determine Moho depth, crustal basement thickness, continental lithosphere thinning (1-1/β) and ocean-continent transition location using a 3D spectral domain gravity inversion method, which incorporates a lithosphere thermal gravity anomaly correction. The continental lithosphere thinning distribution, used to define the initial thermal model temperature perturbation is derived from the gravity inversion and uses no a priori isochron information; as a consequence the gravity inversion method provides a prediction of ocean-continent transition location, which is independent of ocean isochron information. The gravity anomaly contribution from ice thickness is included in the gravity inversion, as is the contribution from sediments which assumes a compaction controlled sediment density increase with depth. Data used in the gravity inversion are elevation and bathymetry, free-air gravity anomaly, the most recent Bedmap2 ice thickness and bedrock topography compilation south of 60 degrees south (Fretwell et al., 2013) and relatively sparse constraints on sediment thickness. Our gravity inversion study predicts thick crust (> 45 km) under interior East Antarctica penetrated by narrow continental rifts that feature relatively thinner crust. The East Antarctic Rift System (EARS) is a major Permian to Cretaceous age rift system that appears to extend from the continental margin at the Lambert Rift to the South Pole region, a distance of 2500 km. This is comparable in scale to the well-studied East African rift system. Intermediate crustal thickness with an inferred linear rift fabric is predicted under Coates Land. An extensive region of either thick oceanic crust or highly thinned continental crust is predicted offshore Oates Land and north Victoria Land, and also off West Antarctica
Arkani-Hamed, Nima; Cohen, Andrew G.; Georgi, Howard
2001-03-16
We discuss the form of the chiral anomaly on an S1/Z2 orbifold with chiral boundary conditions. We find that the 4-divergence of the higher-dimensional current evaluated at a given point in the extra dimension is proportional to the probability of finding the chiral zero mode there. Nevertheless the anomaly, appropriately defined as the five dimensional divergence of the current, lives entirely on the orbifold fixed planes and is independent of the shape of the zero mode. Therefore long distance four dimensional anomaly cancellation ensures the consistency of the higher dimensional orbifold theory.
Signature change in loop quantum gravity: General midisuperspace models and dilaton gravity
Bojowald, Martin
2016-01-01
Models of loop quantum gravity based on real connections have a deformed notion of general covariance, which leads to the phenomenon of signature change. This result is confirmed here in a general analysis of all midisuperspace models without local degrees of freedom. As a subclass of models, 2-dimensional theories of dilaton gravity appear, but a larger set of examples is possible based only on the condition of anomaly freedom. While the classical dilaton gravity models are the only such systems without deformed covariance, they do give rise to signature change when holonomy modifications are included.
Theoretically Optimal Distributed Anomaly Detection
National Aeronautics and Space Administration — A novel general framework for distributed anomaly detection with theoretical performance guarantees is proposed. Our algorithmic approach combines existing anomaly...
Stochastic gravity: beyond semiclassical gravity
Verdaguer, E [Departament de Fisica Fonamental and CER en Astrofisica, Fisica de Particules i Cosmologia, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona (Spain)
2007-05-15
The back-reaction of a classical gravitational field interacting with quantum matter fields is described by the semiclassical Einstein equation, which has the expectation value of the quantum matter fields stress tensor as a source. The semiclassical theory may be obtained from the quantum field theory of gravity interacting with N matter fields in the large N limit. This theory breaks down when the fields quantum fluctuations are important. Stochastic gravity goes beyond the semiclassical limit and allows for a systematic and self-consistent description of the metric fluctuations induced by these quantum fluctuations. The correlation functions of the metric fluctuations obtained in stochastic gravity reproduce the correlation functions in the quantum theory to leading order in an 1/N expansion. Two main applications of stochastic gravity are discussed. The first, in cosmology, to obtain the spectrum of primordial metric perturbations induced by the inflaton fluctuations, even beyond the linear approximation. The second, in black hole physics, to study the fluctuations of the horizon of an evaporating black hole.
Anomaly Detection in Sequences
National Aeronautics and Space Administration — We present a set of novel algorithms which we call sequenceMiner, that detect and characterize anomalies in large sets of high-dimensional symbol sequences that...
Neutrino anomalies without oscillations
Sandip Pakvasa
2000-01-01
I review explanations for the three neutrino anomalies (solar, atmospheric and LSND) which go beyond the `conventional' neutrino oscillations induced by mass-mixing. Several of these require non-zero neutrino masses as well.
Silveirinha, Mario G
2016-01-01
In time-reversal invariant electronic systems the scattering matrix is anti-symmetric. This property enables an effect, designated here as "scattering anomaly", such that the electron transport does not suffer from back reflections, independent of the specific geometry of the propagation path or the presence of time-reversal invariant defects. In contrast, for a generic time-reversal invariant photonic system the scattering matrix is symmetric and there is no similar anomaly. Here, it is theoretically proven that despite these fundamental differences there is a wide class of photonic platforms - in some cases formed only by time-reversal invariant media - in which the scattering anomaly can occur. It is shown that an optical system invariant under the action of the composition of the time-reversal, parity and duality operators is characterized by an anti-symmetric scattering matrix. Specific examples of photonic platforms wherein the scattering anomaly occurs are given, and it is demonstrated with full wave n...
Global gravity field recovery from the ARISTOTELES satellite mission
Visser, P. N. A. M.; Wakker, K. F.; Ambrosius, B. A. C.
1994-02-01
One of the primary objectives of the future ARISTOTELES satellite mission is to map Earth's gravity field with high resolution and accuracy. In order to achieve this objective, the ARISTOTELES satellite will be equipped with a gravity gradiometer and a Global Positioning System (GPS) receiver. Global gravity field error analyses have been performed for several combinations of gradiometer and GPS observations. These analyses indicated that the bandwidth limitation of the gradiometer prevents a stable high-accuracy, high-resolution gravity solution if no additional information is available. However, with the addition of high-accuracy GPS observations, a stable gravity field solution can be obtained. A combination of the measurements acquired by the high-quality GPS receiver and the bandwidth-limited gradiometer on board ARISTOTELES will yield a global gravity field model with a resolution of less than 100 km and with an accuracy of better than 5 mGal for gravity anomalies and 10 cm for geoid undulations.
Guo, X.; Ditmar, P.; Zhao, Q.; Klees, R.; Farahani, H. H.
2017-09-01
GPS data collected by satellite gravity missions can be used for extracting the long-wavelength part of the Earth's gravity field. We propose a new data processing method which makes use of the `average acceleration' approach to gravity field modelling. In this method, satellite accelerations are directly derived from GPS carrier phase measurements with an epoch-differenced scheme. As a result, no ambiguity solutions are needed and the systematic errors that do not change much from epoch to epoch are largely eliminated. The GPS data collected by the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite mission are used to demonstrate the added value of the proposed method. An analysis of the residual accelerations shows that accelerations derived in this way are more precise, with noise being reduced by about 20 and 5% at the cross-track component and the other two components, respectively, as compared to those based on kinematic orbits. The accelerations obtained in this way allow the recovery of the gravity field to a slightly higher maximum degree compared to the solution based on kinematic orbits. Furthermore, the gravity field solution has an overall better performance. Errors in spherical harmonic coefficients are smaller, especially at low degrees. The cumulative geoid height error is reduced by about 15 and 5% up to degree 50 and 150, respectively. An analysis in the spatial domain shows that large errors along the geomagnetic equator, which are caused by a high electron density coupled with large short-term variations, are substantially reduced. Finally, the new method allows for a better observation of mass transport signals. In particular, sufficiently realistic signatures of regional mass anomalies in North America and south-west Africa are obtained.
Guo, X.; Ditmar, P.; Zhao, Q.; Klees, R.; Farahani, H. H.
2017-02-01
GPS data collected by satellite gravity missions can be used for extracting the long-wavelength part of the Earth's gravity field. We propose a new data processing method which makes use of the `average acceleration' approach to gravity field modelling. In this method, satellite accelerations are directly derived from GPS carrier phase measurements with an epoch-differenced scheme. As a result, no ambiguity solutions are needed and the systematic errors that do not change much from epoch to epoch are largely eliminated. The GPS data collected by the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite mission are used to demonstrate the added value of the proposed method. An analysis of the residual accelerations shows that accelerations derived in this way are more precise, with noise being reduced by about 20 and 5% at the cross-track component and the other two components, respectively, as compared to those based on kinematic orbits. The accelerations obtained in this way allow the recovery of the gravity field to a slightly higher maximum degree compared to the solution based on kinematic orbits. Furthermore, the gravity field solution has an overall better performance. Errors in spherical harmonic coefficients are smaller, especially at low degrees. The cumulative geoid height error is reduced by about 15 and 5% up to degree 50 and 150, respectively. An analysis in the spatial domain shows that large errors along the geomagnetic equator, which are caused by a high electron density coupled with large short-term variations, are substantially reduced. Finally, the new method allows for a better observation of mass transport signals. In particular, sufficiently realistic signatures of regional mass anomalies in North America and south-west Africa are obtained.
de Diego, Jose A
2008-01-01
Analysis of the radio-metric data from Pioneer 10 and 11 spacecrafts has indicated the presence of an unmodeled acceleration starting at 20 AU, which has become known as the Pioneer anomaly. The nature of this acceleration is uncertain. In this paper we give a description of the effect and review some relevant mechanisms proposed to explain the observed anomaly. We also discuss on some future projects to investigate this phenomenon.
Boyda, E; Pierce, A T; Boyda, Ed; Murayama, Hitoshi; Pierce, Aaron
2002-01-01
We offer a guide to dimensional reduction (DRED) in theories with anomaly mediated supersymmetry breaking. Evanescent operators proportional to epsilon arise in the bare Lagrangian when it is reduced from d=4 to d= (4-2 epsilon) dimensions. In the course of a detailed diagrammatic calculation, we show that inclusion of these operators is crucial. The evanescent operators conspire to drive the supersymmetry-breaking parameters along anomaly-mediation trajectories across heavy particle thresholds, guaranteeing the ultraviolet insensitivity.
Worldwide complete spherical Bouguer and isostatic anomaly maps
Bonvalot, S.; Balmino, G.; Briais, A.; Peyrefitte, A.; Vales, N.; Biancale, R.; Gabalda, G.; Reinquin, F.
2011-12-01
We present here a set of digital maps of the Earth's gravity anomalies (surface "free air", Bouguer and isostatic), computed at Bureau Gravimetric International (BGI) as a contribution to the Global Geodetic Observing Systems (GGOS) and to the global geophysical maps published by the Commission for the Geological Map of the World (CGMW). The free air and Bouguer anomaly concept is extensively used in geophysical interpretation to investigate the density distributions in the Earth's interior. Complete Bouguer anomalies (including terrain effects) are usually computed at regional scales by integrating the gravity attraction of topography elements over and beyond a given area (under planar or spherical approximations). Here, we developed and applied a worldwide spherical approach aimed to provide a set of homogeneous and high resolution gravity anomaly maps and grids computed at the Earth's surface, taking into account a realistic Earth model and reconciling geophysical and geodetic definitions of gravity anomalies. This first version (1.0) has been computed by spherical harmonics analysis / synthesis of the Earth's topography-bathymetry up to degree 10800. The detailed theory of the spherical harmonics approach is given in Balmino et al., (Journal of Geodesy, submitted). The Bouguer and terrain corrections have thus been computed in spherical geometry at 1'x1' resolution using the ETOPO1 topography/bathymetry, ice surface and bedrock models from the NOAA (National Oceanic and Atmospheric Administration) and taking into account precise characteristics (boundaries and densities) of major lakes, inner seas, polar caps and of land areas below sea level. Isostatic corrections have been computed according to the Airy Heiskanen model in spherical geometry for a constant depth of compensation of 30km. The gravity information given here is provided by the Earth Geopotential Model (EGM2008), developed at degree 2160 by the National Geospatial Intelligence Agency (NGA) (Pavlis
Magnetic anomalies of offshore Krishna-Godavari Basin, eastern continental margin of India
K V Swamy; I V Radhakrishna Murthy; K S Krishna; K S R Murthy; A S Subrahmanyam; M M Malleswara Rao
2009-08-01
The marine magnetic data acquired from offshore Krishna–Godavari (K–G) basin, eastern continental margin of India (ECMI), brought out a prominent NE–SW trending feature, which could be explained by a buried structural high formed by volcanic activity. The magnetic anomaly feature is also associated with a distinct negative gravity anomaly similar to the one associated with 85°E Ridge. The gravity low could be attributed to a flexure at the Moho boundary, which could in turn be filled with the volcanic material. Inversion of the magnetic and gravity anomalies was also carried out to establish the similarity of anomalies of the two geological features (structural high on the margin and the 85°E Ridge) and their interpretations. In both cases, the magnetic anomalies were caused dominantly by the magnetization contrast between the volcanic material and the surrounding oceanic crust, whereas the low gravity anomalies are by the flexures of the order of 3–4 km at Moho boundary beneath them. The analysis suggests that both structural high present in offshore Krishna–Godavari basin and the 85°E Ridge have been emplaced on relatively older oceanic crust by a common volcanic process, but at discrete times, and that several of the gravity lows in the Bay of Bengal can be attributed to flexures on the Moho, each created due to the load of volcanic material.
SADM potentiometer anomaly investigations
Wood, Brian; Mussett, David; Cattaldo, Olivier; Rohr, Thomas
2005-07-01
During the last 3 years Contraves Space have been developing a Low Power (1-2kW) Solar Array Drive Mechanism (SADM) aimed at small series production. The mechanism was subjected to two test programmes in order to qualify the SADM to acceptable levels. During the two test programmes, anomalies were experienced with the Potentiometers provided by Eurofarad SA and joint investigations were undertaken to resolve why these anomalies had occurred. This paper deals with the lessons learnt from the failure investigation on the two Eurofarad (rotary) Potentiometer anomaly. The Rotary Potentiometers that were used were fully redundant; using two back to back mounted "plastic tracks". It is a pancake configuration mounted directly to the shaft of the Slip Ring Assembly at the extreme in-board end of the SADM. It has no internal bearings. The anomaly initially manifested itself as a loss of performance in terms of linearity, which was first detected during Thermal Vacuum testing. A subsequent anomaly manifested itself by the complete failure of the redundant potentiometer again during thermal vacuum testing. This paper will follow and detail the chain of events following this anomaly and identifies corrective measures to be applied to the potentiometer design and assembly process.
Vincent, S.; Marsh, J. G.
1973-01-01
A global detailed gravimetric geoid has been computed by combining the Goddard Space Flight Center GEM-4 gravity model derived from satellite and surface gravity data and surface 1 deg-by-1 deg mean free air gravity anomaly data. The accuracy of the geoid is + or - 2 meters on continents, 5 to 7 meters in areas where surface gravity data are sparse, and 10 to 15 meters in areas where no surface gravity data are available. Comparisons have been made with the astrogeodetic data provided by Rice (United States), Bomford (Europe), and Mather (Australia). Comparisons have also been carried out with geoid heights derived from satellite solutions for geocentric station coordinates in North America, the Caribbean, Europe, and Australia.
The Interpretation of Enceladus Gravity (Invited)
Stevenson, D. J.; Iess, L.; Parisi, M.; Ducci, M.; Asmar, S. W.
2013-12-01
The determination of the gravity field by Cassini is challenging because of the small mass and short duration of the gravitational interaction, even with data from three encounters. E19 data have been successfully integrated into the multiarc analysis, providing a stable and consistent gravity field. This required inclusion of the effect of atmospheric drag due to Enceladus' plumes. This presentation will deal only with the interpretation of these data. The dominant features of the non-central gravity are large values for the harmonic coefficients J2 and C22 and a much smaller but statistically significant negative J3. The value of J2/C22=3.55×0.05 is moderately in excess of the value of 10/3 that applies to a synchronously rotating body with no lateral variation in material properties. Given the obvious latitudinal variation of Enceladus' physical characteristics, primarily expressed by the activity centered on the South Pole, it is plausible that the deviation from 10/3 arises primarily because of a positive anomaly in J2 rather than any anomaly in C22. However, applying Radau-Darwin to the value of C22/q (where q is the usual dimensionless measure of the centrifugal effect on gravity) implies that the moment of inertia is about 0.34MR^2. The high heat output and indirect inference for liquid water suggests a fully differentiated Enceladus. For the known mean density and any plausible mantle density, this would require an unreasonably low core density of 2.5 g/cc or less. A more realistic interpretation is that both J2 and C22 are modestly non-hydrostatic, but that J2 is affected more because of a negative mass anomaly in the Southern hemisphere, consistent with the observed negative J3. One non-unique way to reconcile the observed gravity with a realistic MOI of 0.32 to 0.33MR^2 is to assume that the rocky core of Enceladus has retained some memory of a previous faster rotational state. Even if the ice shell is perfectly relaxed, this reconciles the data for a
Mariana Arc structure inferred from gravity and seismic data
Sager, W. W.
1980-10-01
A two-dimensional gravity model of the lithosphere was constructed along a seismic refraction line near 18°N latitude. Included in the model are crustal layers constrained by seismic refraction results, an estimate of the gravity anomaly caused by the subducting slab, and a model of the low-density mantle beneath the Mariana Trough. With a reasonable anomaly assumed for the slab it is shown that the gravity anomaly caused by the low-density mantle is greatest over the axial bathymetric high and tapers off to the sides. With the bottom of the low-density mantle set at 200 km the density contrast is -0.033 g/cm3. Other depths and densities are tried as well. Several notable anomalies are found on the crustal layers. East of the trench, the crust has been thinned slightly to account for an outer gravity high. Behind the landward wall of the trench, a small, low-density body is modeled to explain a slight offset of the minimum of the free air anomaly from the trench axis. A 50-mGal jump on the observed gravity over the volcanic line is explained by an unusual configuration of the frontal arc Moho.
Silkeborg gravity high revisited: Horizontal extension of the source and its uniqueness
Strykowski, Gabriel
2000-01-01
Silkeborg Gravity High is a dominant positive gravity anomaly in Denmark. It is associated with an igneous intrusion within the crust. A deep refraction seismic profile locates the top of the intrusion in depths between 11 km and 25 Inn. The present contribution should be read together with two...... of the refraction seismic profile. The present paper is an attempt to extend this result to the rest of the sedimentary basin. Of particular interest is another positive gravity anomaly (another intrusion?) located to the north-west of the studied anomaly. A "final model" obtained here estimates the depth...
Galathea-3: A global marine gravity profile
Strykowski, Gabriel; Cordua, Knud Skou; Forsberg, René
2012-01-01
topography. This paper reports on the second experiment in which a continuous marine gravity profile along the ship’s route was measured. The focus of the paper is on the practical aspects of such large scale world wide operation and on the challenges of the data processing. Furthermore, the processed free......-air gravity values are compared to 3 global models: EGM96, EGM08 and DNSC08. Even though the along-track resolution of marine data is higher than the resolution in any global gravity model (which influences the direct comparison of the collected marine data to the model) the statistics for the residual free......-air gravity anomalies show, that EGM08 and DNSC08 are better models than EGM96 for all Galathea-3 legs. Some areas along the ships route are quite challenging for modellers....
Galathea-3: A global marine gravity profile
Strykowski, Gabriel; Cordua, Knud Skou; Forsberg, René
2012-01-01
-air gravity values are compared to 3 global models: EGM96, EGM08 and DNSC08. Even though the along-track resolution of marine data is higher than the resolution in any global gravity model (which influences the direct comparison of the collected marine data to the model) the statistics for the residual free......-air gravity anomalies show, that EGM08 and DNSC08 are better models than EGM96 for all Galathea-3 legs. Some areas along the ships route are quite challenging for modellers....... topography. This paper reports on the second experiment in which a continuous marine gravity profile along the ship’s route was measured. The focus of the paper is on the practical aspects of such large scale world wide operation and on the challenges of the data processing. Furthermore, the processed free...
An analysis of the gravity field and tectonic evaluation of the northwestern part of Bangladesh
Khan, A. A.; Rahman, T.
1992-06-01
The total Bouguer anomaly values of the northwestern part of Bangladesh have been analysed on the basis of the trend, shape and magnitude of the anomaly values. Residual gravity and the second vertical derivatives of gravity show only two near-surface features, viz. the Nilphamari and Rangpur highs. Geological models of the two highs have been constructed on the basis of gravity modelling. Gravity data, in conjunction with aeromagnetic and bore hole data, enable us to propose four tectonic elements of the northwestern part of Bangladesh: the Northern Slope of the Platform, the Stable Platform, the Nawabganj-Gaibandha Intracratonic High and the Southern Part of the Platform.
Tscherning, Carl Christian; Herceg, Matija; Fredenslund Levinsen, Joanna
GOCE TRF (terrestrial reference frame) vertical anomalous gradients (Tzz) from two periods have been used to determine gravity anomalies changes in mid-west Greenland, where a large mass-loss has been detected using GRACE (Fig. 1). As additional data were used the GOCE DIR-3 model and ground...... gravity at the coast on solid rock, where no mass loss is expected. The methods of Least-Squares Collocation (LSC) and the Reduced Point Mass (RPM) methods have been used, however only LSC included the ground data....
Identification of Baribis fault - West Java using second vertical derivative method of gravity
Sari, Endah Puspita; Subakti, Hendri
2015-04-01
Baribis fault is one of West Java fault zones which is an active fault. In modern era, the existence of fault zone can be observed by gravity anomaly. Baribis fault zone has not yet been measured by gravity directly. Based on this reason, satellite data supported this research. Data used on this research are GPS satellite data downloaded from TOPEX. The purpose of this research is to determine the type and strike of Baribis fault. The scope of this research is Baribis fault zone which lies on 6.50o - 7.50o S and 107.50o - 108.80o E. It consists of 5146 points which one point to another is separated by 1 minute meridian. The method used in this research is the Second Vertical Derivative (SVD) of gravity anomaly. The Second Vertical Derivative of gravity anomaly show as the amplitude of gravity anomaly caused by fault structure which appears as residual anomaly. The zero value of residual gravity anomaly indicates that the contact boundary of fault plane. Second Vertical Derivative method of gravity was applied for identifying Baribis fault. The result of this research shows that Baribis fault has a thrust mechanism. It has a lineament strike varies from 107o to 127o. This result agrees with focal mechanism data of earthquakes occurring on this region based on Global CMT catalogue.
Anomalies without Massless Particles
Gurlanik, Z
1994-01-01
Baryon and lepton number in the standard model are violated by anomalies, even though the fermions are massive. This problem is studied in the context of a two dimensional model. In a uniform background field, fermion production arise from non-adiabatic behavior that compensates for the absence of massless modes. On the other hand, for localized instanton-like configurations, there is an adiabatic limit. In this case, the anomaly is produced by bound states which travel across the mass gap. The sphaleron corresponds to a bound state at the halfway point.
Farhoudi, M.
1995-01-01
We seek an analogy of the mathematical form of the alternative form of Einstein's field equations for Lovelock's field equations. We find that the price for this analogy is to accept the existence of the trace anomaly of the energy-momentum tensor even in classical treatments. As an example, we take this analogy to any generic second order Lagrangian and exactly derive the trace anomaly relation suggested by Duff. This indicates that an intrinsic reason for the existence of such a relation sh...
Congenital laryngeal anomalies,
Michael J. Rutter
2014-12-01
Full Text Available Introduction: It is essential for clinicians to understand issues relevant to the airway management of infants and to be cognizant of the fact that infants with congenital laryngeal anomalies are at particular risk for an unstable airway. Objectives: To familiarize clinicians with issues relevant to the airway management of infants and to present a succinct description of the diagnosis and management of an array of congenital laryngeal anomalies. Methods: Revision article, in which the main aspects concerning airway management of infants will be analyzed. Conclusions: It is critical for clinicians to understand issues relevant to the airway management of infants.
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.
Sedimentary basin analysis using airborne gravity data: a case study from the Bohai Bay Basin, China
Li, Wenyong; Liu, Yanxu; Zhou, Jianxin; Zhou, Xihua; Li, Bing
2016-11-01
In this paper, we discuss the application of an airborne gravity survey to sedimentary basin analysis. Using high-precision airborne gravity data constrained by drilling and seismic data from the Bohai Bay Basin in eastern China, we interpreted faults, structural elements, sedimentary thickness, structural styles and local structures (belts) in the central area of the Basin by the wavelet transform method. Subsequently, these data were subtracted from the Bouguer gravity to calculate the residual gravity anomalies. On this basis, the faults were interpreted mainly by linear zones of high gravity gradients and contour distortion, while the sedimentary thicknesses were computed by the Euler deconvolution. The structural styles were identified by the combination of gravity anomalies and the local structures interpreted by the first vertical derivative of the residual gravity. The results showed evidence for seven faults, one sag and ten new local structure belts.
Congenital anomalies in Primorsky region.
Kiku, P; Voronin, S; Golokhvast, K
2015-01-01
has increased dramatically since 2000. This was due to the beginning of activities of medicogenetic service since 1998: the legal framework and information database were created, the flow of pregnant women was formed actively, and invasive prenatal diagnosis was introduced.Incidence of congenital anomalies has a reliable statistical association (chi-square) with bioclimatic zones and ecological situation. The high level of pathology is observed in both teenagers and children in the critical environmental situation areas, where there are enterprises of coal, mining and chemical industry, ship repair, construction, engineering sites, and areas with intensive chemical use and improvement of agriculture. For the most part these are cities and districts of the region where more than a half of the major manufacturing plants of the 1st and 2nd hazard classes are located. Exceeding the maximum allowable concentrations (MAC) of harmful substances in the air, soil, and water in these areas often reaches tenfold. It should be noted that in the territories with the critical environmental situation a relatively high level of malformations is observed in adolescents in the continental bioclimatic zone, and in children - on the coast, suggesting the influence of different climatic factors. Also a high level of the same congenital anomalies was revealed in children in bioclimatic zones of the coast and transition zones with the intense environmental situation.According to the results of the regression analysis, the varying degrees of influence of ecological and hygienic factors on the incidence of congenital anomalies were determined. In children, up to 77.3% of the spread of pathology depends on the complex of parameters of the environment; the proportion of the influence of sanitary and hygienic indicators is 63.1%, and natural and climatic indicators - 14.2%. Such factors as the characteristics of the soil condition, the level of air pollution, chemical pollution and adverse
National Oceanic and Atmospheric Administration, Department of Commerce — This data base (14,559 records) was received in January 1986. Principal gravity parameters include elevation and observed gravity. The observed gravity values are...
National Oceanic and Atmospheric Administration, Department of Commerce — The NGS Absolute Gravity data (78 stations) was received in July 1993. Principal gravity parameters include Gravity Value, Uncertainty, and Vertical Gradient. The...
Gravity Anomalies and Estimated Topography Derived from Satellite Altimetry
National Oceanic and Atmospheric Administration, Department of Commerce — In many areas of the global ocean, the depth of the seafloor is not well known because survey lines by ships are hundreds of kilometers apart. Satellites carrying...
Recovery of Gravity Anomalies from Gridded Geoid Height Data.
1976-07-01
Heiskanen and • Mori tz [5] , - ~2(N) = ~~~ - - ~ Q2 C,~ (28)“ n=K+l n 5 5 where = f S(4’)P~(cos 4’)sin~ d4’, (29) S S C~ is the degree var i ance... Heiskanen , W.A. and H. Moritz; Physical Geodesy; W.H. Freeman and Co.; San Francisco, Cal ifornia; 1967. - - - 6. Moritz, H.; Advanced Least—Squares Methods
The reactor antineutrino anomalies
Haser, Julia; Buck, Christian; Lindner, Manfred [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany)
2016-07-01
Major discoveries were made in the past few years in the field of neutrino flavour oscillation. Nuclear reactors produce a clean and intense flux of electron antineutrinos and are thus an essential neutrino source for the determination of oscillation parameters. Most currently the reactor antineutrino experiments Double Chooz, Daya Bay and RENO have accomplished to measure θ{sub 13}, the smallest of the three-flavour mixing angles. In the course of these experiments two anomalies emerged: (1) the reanalysis of the reactor predictions revealed a deficit in experimentally observed antineutrino flux, known as the ''reactor antineutrino anomaly''. (2) The high precision of the latest generation of neutrino experiments resolved a spectral shape distortion relative to the expected energy spectra. Both puzzles are yet to be solved and triggered new experimental as well as theoretical studies, with the search for light sterile neutrinos as most popular explanation for the flux anomaly. This talk outlines the two reactor antineutrino anomalies. Discussing possible explanations for their occurrence, recent and upcoming efforts to solve the reactor puzzles are highlighted.
National Oceanic and Atmospheric Administration, Department of Commerce — A 1 kilometer Bouguer anomaly grid for the country of Bolivia.Number of columns is 550 and number of rows is 900. The order of the data is from the lower left to the...
Minnesota Bouguer Anomaly Grid
National Oceanic and Atmospheric Administration, Department of Commerce — A 1.5 kilometer Bouguer anomaly grid for the state of Minnesota. Number of columns is 404 and number of rows is 463. The order of the data is from the lower left to...
Bouguer gravity regional and residual separation application to geology and environment
Mallick, K; Sharma, KK
2012-01-01
Resolving regional and residual components arising out of deeper and shallower sources in observed Bouguer gravity anomalies is an old problem. The technique covered here is an attempt to sort out the difficulties that performs better than existing methods.
Astrometric solar system anomalies
Nieto, Michael Martin [Los Alamos National Laboratory; Anderson, John D [PROPULSION LABORATORY
2009-01-01
There are at least four unexplained anomalies connected with astrometric data. perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it often experiences a change in total orbital energy per unit mass. next, a secular change in the astronomical unit AU is definitely a concern. It is increasing by about 15 cm yr{sup -1}. The other two anomalies are perhaps less disturbing because of known sources of nongravitational acceleration. The first is an apparent slowing of the two Pioneer spacecraft as they exit the solar system in opposite directions. Some astronomers and physicists are convinced this effect is of concern, but many others are convinced it is produced by a nearly identical thermal emission from both spacecraft, in a direction away from the Sun, thereby producing acceleration toward the Sun. The fourth anomaly is a measured increase in the eccentricity of the Moon's orbit. Here again, an increase is expected from tidal friction in both the Earth and Moon. However, there is a reported unexplained increase that is significant at the three-sigma level. It is produent to suspect that all four anomalies have mundane explanations, or that one or more anomalies are a result of systematic error. Yet they might eventually be explained by new physics. For example, a slightly modified theory of gravitation is not ruled out, perhaps analogous to Einstein's 1916 explanation for the excess precession of Mercury's perihelion.
Viktor T. Toth
2010-09-01
Full Text Available Radio-metric Doppler tracking data received from the Pioneer 10 and 11 spacecraft from heliocentric distances of 20-70 AU has consistently indicated the presence of a small, anomalous, blue-shifted frequency drift uniformly changing with a rate of ~6 × 10–9 Hz/s. Ultimately, the drift was interpreted as a constant sunward deceleration of each particular spacecraft at the level of aP = (8.74 ± 1.33 × 10–10 m/s2. This apparent violation of the Newton's gravitational inverse square law has become known as the Pioneer anomaly; the nature of this anomaly remains unexplained. In this review, we summarize the current knowledge of the physical properties of the anomaly and the conditions that led to its detection and characterization. We review various mechanisms proposed to explain the anomaly and discuss the current state of efforts to determine its nature. A comprehensive new investigation of the anomalous behavior of the two Pioneers has begun recently. The new efforts rely on the much-extended set of radio-metric Doppler data for both spacecraft in conjunction with the newly available complete record of their telemetry files and a large archive of original project documentation. As the new study is yet to report its findings, this review provides the necessary background for the new results to appear in the near future. In particular, we provide a significant amount of information on the design, operations and behavior of the two Pioneers during their entire missions, including descriptions of various data formats and techniques used for their navigation and radio-science data analysis. As most of this information was recovered relatively recently, it was not used in the previous studies of the Pioneer anomaly, but it is critical for the new investigation.
Gravity Variation in Siberia: GRACE Observation and Possible Causes
Benjamin Fong Chao
2011-01-01
Full Text Available We report the finding, from the GRACE observation, of an increasing trend in the gravity anomaly in Siberia at the rate of up to 0.5 ugal yr-1 during 2003/1 - 2009/12, in the backdrop of a negative anomaly of magnitude on the order of ~-10 mgal. In consideration of the non-uniqueness of the gravitational inverse problem, we examine in some detail the various possible geophysical causes to explain the increasing gravity signal. We find two geophysical mechanisms being the most plausible, namely the melting of permafrost and the GIA post-glacial rebound. We conclude that these two mechanisms cannot be ruled out as causes for the regional gravity increase in Siberia, based on gravity data and in want of ancillary geophysical data in the region. More definitive identification of the contributions of the various causes awaits further studies.
Solar-system tests of the relativistic gravity
Ni, Wei-Tou
2016-01-01
In 1859, Le Verrier discovered the Mercury perihelion advance anomaly. This anomaly turned out to be the first relativistic-gravity effect observed. During the 156 years to 2016, the precisions and accuracies of laboratory and space experiments, and of astrophysical and cosmological observations on relativistic gravity have been improved by 3-4 orders of magnitude. The improvements have been mainly from optical observations at first followed by radio observations. The achievements for the past 50 years are from radio Doppler tracking and radio ranging together with lunar laser ranging. At the present, the radio observations and lunar laser ranging experiments are similar in the accuracy of testing relativistic gravity. We review and summarize the present status of solar-system tests of relativistic gravity. With planetary laser ranging, spacecraft laser ranging and interferometric laser ranging (laser Doppler ranging) together with the development of drag-free technology, the optical observations will improve...
Ponce, David A.; Mankinen, E.A.; Davidson, J.G.; Morin, R.L.; Blakely, R.J.
2000-01-01
An isostatic gravity map of the Nevada Test Site area was prepared from publicly available gravity data (Ponce, 1997) and from gravity data recently collected by the U.S. Geological Survey (Mankinen and others, 1999; Morin and Blakely, 1999). Gravity data were processed using standard gravity data reduction techniques. Southwest Nevada is characterized by gravity anomalies that reflect the distribution of pre-Cenozoic carbonate rocks, thick sequences of volcanic rocks, and thick alluvial basins. In addition, regional gravity data reveal the presence of linear features that reflect large-scale faults whereas detailed gravity data can indicate the presence of smaller-scale faults.
Nash, Patrick Lee
2010-01-01
A theory of a new gravitational interaction is described. This theory follows naturally from a new Lagrangian formulation of Maxwell's theory for photons and electrons (and positrons) whose associated Euler Lagrange equations imply the conventional Maxwell equations, but which possesses new \\textbf{\\emph{bosonic}} spinor degrees of freedom that may be associated with a new type of fundamental gravitational interaction. The precise character of this gravitational interaction with a photon vector potential is explicitly defined in terms of a local U(1)-invariant Lagrangian in Eq.[\\ref{Lagrangian3}]. However in Section \\ref{ssec:Simple-Cosmolo-Model}, in order to parallel the well known Friedmann model in cosmology, a phenomenological description of the new gravitational interaction coupled to Newton-Einstein gravity that is sourced by an ideal fluid is discussed. % % To lay the foundation for a description of the new gravitational interaction our new formulation of Maxwell's theory must first be described. It i...
Magueijo, J; Magueijo, Joao; Smolin, Lee
2004-01-01
Non-linear special relativity (or doubly special relativity) is a simple framework for encoding properties of flat quantum space-time. In this paper we show how this formalism may be generalized to incorporate curvature (leading to what might be called ``doubly general relativity''). We first propose a dual to non-linear realizations of relativity in momentum space, and show that for such a dual the space-time invariant is an energy-dependent metric. This leads to an energy-dependent connection and curvature, and a simple modification to Einstein's equations. We then examine solutions to these equations. We find the counterpart to the cosmological metric, and show how cosmologies based upon our theory of gravity may solve the ``horizon problem''. We discuss the Schwarzchild solution, examining the conditions for which the horizon is energy dependent. We finally find the weak field limit.
Lombard, John
2016-01-01
We introduce the construction of a new framework for probing discrete emergent geometry and boundary-boundary observables based on a fundamentally a-dimensional underlying network structure. Using a gravitationally motivated action with Forman weighted combinatorial curvatures and simplicial volumes relying on a decomposition of an abstract simplicial complex into realized embeddings of proper skeletons, we demonstrate properties such as a minimal volume-scale cutoff, the necessity of a positive-definite cosmological constant as a regulator for non-degenerate geometries, and naturally emergent simplicial structures from Metropolis network evolution simulations with no restrictions on attachment rules or regular building blocks. We see emergent properties which echo results from both the spinfoam formalism and causal dynamical triangulations in quantum gravity, and provide analytical and numerical results to support the analogy. We conclude with a summary of open questions and intent for future work in develop...
Models for Near-Ridge Seamounts Constrained by Gravity Observations
Kostlan, M.; McClain, J. S.
2009-12-01
In an analysis of the seamount chain centered at 105°20’W, 9°05’N, west of the East Pacific Rise and south of the Clipperton transform fault, we compared measured free air gravity anomaly values with modeled gravity anomaly values. The seamount chain contains approximately ten seamounts trending roughly east-west, perpendicular to the mid-ocean ridge axis. They lie on lithosphere between 1.5 and 2.7 Ma in age. Based on its position and age, the seamount chain appears to be associated with the 9°03’N overlapping spreading center (OSC). This OSC includes several associated seamount chains, aligned generally east-west, and of varying ages. The observed data include both free air gravity anomalies and bathymetry of the seamount chain, provided by the National Geophysical Data Center (NGDC), and was selected because the gravity measurements are relatively well covered. We used a series of different structural models of the oceanic crust and mantle to generate gravity anomalies associated with the sea mounts. The models utilize Parker’s algorithm to generate these free air gravity anomalies. We compute a gravity residual by subtracting the calculated anomalies from the observed anomalies. The models include one with a crust of a constant thickness (6 km), while another introduces a constant-thickness Layer 2A. In contrast, a third model included a variable thickness crust, where the thickness is governed by Airy compensation. The calculations show that the seamounts must be partly compensated, because the constant-thickness models predict a high negative residual (or they produce an anomaly which is too high). In contrast, the Airy compensation model produces an anomaly that is too low at the longer wavelengths, indicating that the lithosphere must have some strength, and that flexure must be supporting part of the load of the seamount chain. This contrasts with earlier studies that indicate young, near-ridge seamounts do not result in flexure of the thin
Mars gravity - High-resolution results from Viking Orbiter 2
Sjogren, W. L.
1979-01-01
Doppler radio-tracking data have provided detailed measurements for a Martian gravity map extending from 30 deg S to 65 deg N in latitude and through 360 deg of longitude. The feature resolution is approximately 500 km, revealing a huge anomaly associated with Olympus Mons, a mascon in Isidis Planitia, and other anomalies correlated with volcanic structure. Olympus Mons has been modeled with a 600 km surface disk having a mass of 8.7 times 10 to the 21st grams.
Newtonian gravity in loop quantum gravity
Smolin, Lee
2010-01-01
We apply a recent argument of Verlinde to loop quantum gravity, to conclude that Newton's law of gravity emerges in an appropriate limit and setting. This is possible because the relationship between area and entropy is realized in loop quantum gravity when boundaries are imposed on a quantum spacetime.
Newtonian gravity in loop quantum gravity
Smolin, Lee
2010-01-01
We apply a recent argument of Verlinde to loop quantum gravity, to conclude that Newton's law of gravity emerges in an appropriate limit and setting. This is possible because the relationship between area and entropy is realized in loop quantum gravity when boundaries are imposed on a quantum spacetime.
Waste Isolation Pilot Plant (WIPP) site gravity survey and interpretation
Barrows, L.J.; Fett, J.D.
1983-04-01
A portion of the WIPP site has been extensively surveyed with high-precision gravity. The main survey (in T22S, R31E) covered a rectangular area 2 by 4-1/3 mi encompassing all of WIPP site Zone II and part of the disturbed zone to the north of the site. Stations were at 293-ft intervals along 13 north-south lines 880 ft apart. The data are considered accurate to within a few hundredths of a milligal. Long-wavelength gravity anomalies correlate well with seismic time structures on horizons below the Castile Formation. Both the gravity anomalies and the seismic time structures are interpreted as resulting from related density and velocity variations within the Ochoan Series. Shorter wavelength negative gravity anomalies are interpreted as resulting from bulk density alteration in the vicinity of karst conduits. The WIPP gravity survey was unable to resolve low-amplitude, long-wavelength anomalies that should result from the geologic structures within the disturbed zone. It did indicate the degree and character of karst development within the surveyed area.
Herceg, Matija; Artemieva, Irina; Thybo, Hans
2014-01-01
and by introducing variations into the crustal structure which corresponds to the uncertainty of its resolution by highquality and low-quality seismic models. We examine the propagation of these uncertainties into determinations of lithospheric mantle density. Given a relatively small range of expected density......We present a regional model for the density structure of the North American upper mantle. The residual mantle gravity anomalies are based on gravity data derived from the GOCE geopotential models with crustal correction to the gravity field being calculated from a regional crustal model. We analyze...... how uncertainties and errors in the crustal model propagate from crustal densities to mantle residual gravity anomalies and the density model of the upper mantle. Uncertainties in the residual upper (lithospheric) mantle gravity anomalies result from several sources: (i) uncertainties in the velocity-density...
A GOCE only gravity model GOSG01S and the validation of GOCE related satellite gravity models
Xinyu Xu
2017-07-01
Full Text Available We compile the GOCE-only satellite model GOSG01S complete to spherical harmonic degree of 220 using Satellite Gravity Gradiometry (SGG data and the Satellite-to-Satellite Tracking (SST observations along the GOCE orbit based on applying a least-squares analysis. The diagonal components (Vxx, Vyy, Vzz of the gravitational gradient tensor are used to form the system of observation equations with the band-pass ARMA filter. The point-wise acceleration observations (ax, ay, az along the orbit are used to form the system of observation equations up to the maximum spherical harmonic degree/order 130. The analysis of spectral accuracy characteristics of the newly derived gravitational model GOSG01S and the existing models GOTIM04S, GODIR04S, GOSPW04S and JYY_GOCE02S based on their comparison with the ultra-high degree model EIGEN-6C2 reveals a significant consistency at the spectral window approximately between 80 and 190 due to the same period SGG data used to compile these models. The GOCE related satellite gravity models GOSG01S, GOTIM05S, GODIR05S, GOTIM04S, GODIR04S, GOSPW04S, JYY_GOCE02S, EIGEN-6C2 and EGM2008 are also validated by using GPS-leveling data in China and USA. According to the truncation at degree 200, the statistic results show that all GGMs have very similar differences at GPS-leveling points in USA, and all GOCE related gravity models have better performance than EGM2008 in China. This suggests that all these models provide much more information on the gravity field than EGM2008 in areas with low terrestrial gravity coverage. And STDs of height anomaly differences in China for the selected truncation degrees show that GOCE has improved the accuracy of the global models beyond degree 90 and the accuracies of the models improve from 24 cm to 16 cm. STDs of geoid height differences in USA show that GOSG01S model has best consistency comparing with GPS-leveling data for the frequency band of the degree between 20 and 160.
The Impact of Geological Structures On The Gravity Field
Marti, U.
In general, a uniform standard density value is used for the calculation of topographic effects for gravity field modelling in Switzerland. Only a limited number of promi- nent mass anomalies is treated with an individual density. In some regions this causes problems in predicting the surface gravity or the deflections of the vertical. An actual example is the construction of a new 57 km railway tunnel, where accurate deflec- tions of the vertical are needed for the orientation of gyroscope measurements. It was rather doubtful if our standard national gravity field model would fulfil the accuracy demands. Therefore, a refinement of the gravity field model was performed by digi- tising all the relevant geological structures in the vicinity of the planned tunnel. This lead to a 3D density model of irregularly shaped polyhedrons. Their influence on the gravity field (potential, gravity, deflections of the vertical and their first derivatives) are calculated rigorously. First results of this study are now available and reveal that the influences of the geological structures on the deflections of the vertical and on gravity are rather small (1 - 2 arcsec, 3 - 5 mgal) in the investigated region and they are at the limit of significance for the technical applications of levelling or gyroscope mea- surements. The largest effects are caused by quaternary sediments with a large density contrast and by some gneiss structures, which show only a small density contrast but their total mass can cause considerable anomalies in the gravity field.
Gravity survey in the San Luis Valley area, Colorado
Gaca, J. Robert; Karig, Daniel E.
1965-01-01
During the summers of 1963 and 1964, a regional gravity survey covering 6,000 square miles of the San Luis Valley and surrounding areas was made to determine subsurface basement configurations and to guide future crustal studies. The San Luis Valley, a large intermontane basin, is a segment of the Rio Grande trough, a reef system characterized by volcanism, normal faulting, and tilted fault blocks. The gravity data, accurate to about 0.5 mgal, were reduced to complete-Bouguer anomaly values. The Bouguer-anomaly gravity map delineates a series of en-echelon gravity highs in the central and western San Luis Valley. These gravity highs are interpreted as horsts of Precambrian rock buried by basin fill. A series of en-echelon gravity lows along the eastern edge of the Valley is interpreted as a graben filled with sedimentary and igneous rock estimated to be up to 30,000 ft thick. The relatively high regional gravity over the Sangre de Cristo Mountains suggests that these mountains are locally uncompensated. A subcircular gravity low in the Bonanza area is interpreted as an indication of low-density volcanic rocks within a caldera structure.
Toward Joint Inversion of Gravity and Dyanamics
Jacoby, W. R.
To better understand geodynamic processes as seafloor spreading, plumes, subduction, and isostatic adjustment, gravity is inverted with "a prioriinformation from topography/bathymetry, seismic structure and dynamic models. Examples are subduction of the Juan de Fuca plate below Vancouver Island, the passive Black SeaTurkey margin and Iceland ridge-plume interaction. Gravity and other data are averaged 50 km wide strips. Mass balances are estimated (showing also that the free air anomaly is misleading for narrow structures). The mass balances represent plate forces and plate bending, affecting the gravity signals and the isostatic state of continental margins and ridge-plume effects, which are highly correlated in space and cannot be separated without a priori information from modelling. The examples from widely different tectonic situations demonstrate that the art of regional-scale gravity inversion requires extensive background knowledge and inclusion of dynamic processes. It is difficult to conceive any formal, globally applicable procedure taking care of this; it is even a question, what is data, what a priori information? They are not distinguishable if all are included as foreward routines. The "accuracy" of models cannot be perfectly determined, if the "real" mass distribution is not known if known, gravity inversion would be unnecessary. In reality only guesses are possible on the basis of observations and physical laws governing geodynamics. A priori information and gravity data limit the resolution of gravity inversion. Different model types are indistinguishable because adjustments within their parameter uncertainties permit a good fit. But gravity excludes wrong models (Karl Popper: science evolves by falsification of wrong models), and precise gravity guides and defines aims, targets and strategies for new observations.
XYY chromosome anomaly and schizophrenia.
Rajagopalan, M; MacBeth, R; Varma, S L
1998-02-07
Sex chromosome anomalies have been associated with psychoses, and most of the evidence is linked to the presence of an additional X chromosome. We report a patient with XYY chromosome anomaly who developed schizophrenia.
Zotto, Michele Del [Jefferson Physical Laboratory, Harvard University, Cambridge, MA 02138 (United States); Heckman, Jonathan J. [Department of Physics, University of North Carolina, Chapel Hill, NC 27599 (United States); Morrison, David R. [Departments of Mathematics and Physics, University of California, Santa Barbara, Santa Barbara, CA 93106 (United States); Park, Daniel S. [Simons Center for Geometry and Physics, Stony Brook University, Stony Brook, NY 11794-3636 (United States)
2015-06-23
We study how to couple a 6D superconformal field theory (SCFT) to gravity. In F-theory, the models in question are obtained working on the supersymmetric background ℝ{sup 5,1}×B where B is the base of a compact elliptically fibered Calabi-Yau threefold in which two-cycles have contracted to zero size. When the base has orbifold singularities, we find that the anomaly polynomial of the 6D SCFTs can be understood purely in terms of the intersection theory of fractional divisors: the anomaly coefficient vectors are identified with elements of the orbifold homology. This also explains why in certain cases, the SCFT can appear to contribute a “fraction of a hypermultiplet” to the anomaly polynomial. Quantization of the lattice of string charges also predicts the existence of additional light states beyond those captured by such fractional divisors. This amounts to a refinement to the lattice of divisors in the resolved geometry. We illustrate these general considerations with explicit examples, focusing on the case of F-theory on an elliptic Calabi-Yau threefold with base ℙ{sup 2}/ℤ{sub 3}.
Del Zotto, Michele; Morrison, David R; Park, Daniel S
2014-01-01
We study how to couple a 6D superconformal field theory (SCFT) to gravity. In F-theory, the models in question are obtained working on the supersymmetric background R^{5,1} x B where B is the base of a compact elliptically fibered Calabi-Yau threefold in which two-cycles have contracted to zero size. When the base has orbifold singularities, we find that the anomaly polynomial of the 6D SCFTs can be understood purely in terms of the intersection theory of fractional divisors: the anomaly coefficient vectors are identified with elements of the orbifold homology. This also explains why in certain cases, the SCFT can appear to contribute a "fraction of a hypermultiplet" to the anomaly polynomial. Quantization of the lattice of string charges also predicts the existence of additional light states beyond those captured by such fractional divisors. This amounts to a refinement to the lattice of divisors in the resolved geometry. We illustrate these general considerations with explicit examples, focusing on the case...
Del Zotto, Michele; Heckman, Jonathan J.; Morrison, David R.; Park, Daniel S.
2015-06-01
We study how to couple a 6D superconformal field theory (SCFT) to gravity. In F-theory, the models in question are obtained working on the supersymmetric background 5,1 × B where B is the base of a compact elliptically fibered Calabi-Yau threefold in which two-cycles have contracted to zero size. When the base has orbifold singularities, we find that the anomaly polynomial of the 6D SCFTs can be understood purely in terms of the intersection theory of fractional divisors: the anomaly coefficient vectors are identified with elements of the orbifold homology. This also explains why in certain cases, the SCFT can appear to contribute a "fraction of a hypermultiplet" to the anomaly polynomial. Quantization of the lattice of string charges also predicts the existence of additional light states beyond those captured by such fractional divisors. This amounts to a refinement to the lattice of divisors in the resolved geometry. We illustrate these general considerations with explicit examples, focusing on the case of F-theory on an elliptic Calabi-Yau threefold with base.
Maximum Autocorrelation Factorial Kriging
Nielsen, Allan Aasbjerg; Conradsen, Knut; Pedersen, John L.
2000-01-01
This paper describes maximum autocorrelation factor (MAF) analysis, maximum autocorrelation factorial kriging, and its application to irregularly sampled stream sediment geochemical data from South Greenland. Kriged MAF images are compared with kriged images of varimax rotated factors from...
Discrete R Symmetries and Anomalies
Michael Dine(Santa Cruz Institute for Particle Physics and Department of Physics, Santa Cruz CA 95064, U.S.A.); Angelo Monteux(Santa Cruz Institute for Particle Physics, University of California Santa Cruz, 1156 High Street, Santa Cruz, U.S.A.)
2012-01-01
We comment on aspects of discrete anomaly conditions focussing particularly on $R$ symmetries. We review the Green-Schwarz cancellation of discrete anomalies, providing a heuristic explanation why, in the heterotic string, only the "model-independent dilaton" transforms non-linearly under discrete symmetries; this argument suggests that, in other theories, multiple fields might play a role in anomaly cancellations, further weakening any anomaly constraints at low energies. We provide examples...
Cosmological Hints of Modified Gravity ?
Di Valentino, Eleonora; Silk, Joseph
2016-01-01
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...
Induced gravity II: grand unification
Einhorn, Martin B.; Jones, D. R. Timothy
2016-05-01
As an illustration of a renormalizable, asymptotically-free model of induced gravity, we consider an SO(10) gauge theory interacting with a real scalar multiplet in the adjoint representation. We show that dimensional transmutation can occur, spontaneously breaking SO(10) to SU(5)⊗U(1), while inducing the Planck mass and a positive cosmological constant, all proportional to the same scale v. All mass ratios are functions of the values of coupling constants at that scale. Below this scale (at which the Big Bang may occur), the model takes the usual form of Einstein-Hilbert gravity in de Sitter space plus calculable corrections. We show that there exist regions of parameter space in which the breaking results in a local minimum of the effective action giving a positive dilaton (mass)2 from two-loop corrections associated with the conformal anomaly. Furthermore, unlike the singlet case we considered previously, some minima lie within the basin of attraction of the ultraviolet fixed point. Moreover, the asymptotic behavior of the coupling constants also lie within the range of convergence of the Euclidean path integral, so there is hope that there will be candidates for sensible vacua. Although open questions remain concerning unitarity of all such renormalizable models of gravity, it is not obvious that, in curved backgrounds such as those considered here, unitarity is violated. In any case, any violation that may remain will be suppressed by inverse powers of the reduced Planck mass.
Turnaround radius in modified gravity
Faraoni, Valerio
2015-01-01
In an accelerating universe in General Relativity there is a maximum radius above which a shell of test particles cannot collapse, but is dispersed by the cosmic expansion. This radius could be used in conjunction with observations of large structures to constrain the equation of state of the universe. We extend the concept of turnaround radius to modified theories of gravity for which the gravitational slip is non-vanishing.
Lineal gravity from planar gravity
Achúcarro, A
1993-01-01
We show how to obtain the two-dimensional black hole action by dimensional reduction of the three-dimensional Einstein action with a non-zero cosmological constant. Starting from the Chern-Simons formulation of 2+1 gravity, we obtain the 1+1 dimensional gauge formulation given by Verlinde. Remarkably, the proposed reduction shares the relevant features of the formulation of Cangemi and Jackiw, without the need for a central charge in the algebra. We show how the Lagrange multipliersin these formulations appear naturally as the remnants of the three dimensional connection associated to symmetries that have been lostin the dimensional reduction. The proposed dimensional reduction involves a shift in the three dimensional connection whose effect is to make the length of the extra dimension infinite.
Chen, Mu-Chun, E-mail: muchunc@uci.edu [Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575 (United States); Fallbacher, Maximilian, E-mail: m.fallbacher@tum.de [Physik–Department T30, Technische Universität München, James–Franck–Straße 1, 85748 Garching (Germany); Ratz, Michael, E-mail: michael.ratz@tum.de [Physik–Department T30, Technische Universität München, James–Franck–Straße 1, 85748 Garching (Germany); Trautner, Andreas, E-mail: andreas.trautner@tum.de [Physik–Department T30, Technische Universität München, James–Franck–Straße 1, 85748 Garching (Germany); Excellence Cluster Universe, Boltzmannstraße 2, 85748 Garching (Germany); Vaudrevange, Patrick K.S., E-mail: patrick.vaudrevange@tum.de [Excellence Cluster Universe, Boltzmannstraße 2, 85748 Garching (Germany); TUM Institute for Advanced Study, Lichtenbergstraße 2a, 85748 Garching (Germany); Arnold Sommerfeld Center for Theoretical Physics, Ludwig–Maximilians–Universität München, Theresienstraße 37, 80333 München (Germany)
2015-07-30
We show that there is a class of finite groups, the so-called perfect groups, which cannot exhibit anomalies. This implies that all non-Abelian finite simple groups are anomaly-free. On the other hand, non-perfect groups generically suffer from anomalies. We present two different ways that allow one to understand these statements.
Mu-Chun Chen
2015-07-01
Full Text Available We show that there is a class of finite groups, the so-called perfect groups, which cannot exhibit anomalies. This implies that all non-Abelian finite simple groups are anomaly-free. On the other hand, non-perfect groups generically suffer from anomalies. We present two different ways that allow one to understand these statements.
Katsuya Hasegawa
2014-04-01
Full Text Available The ability to maintain the body relative to the external environment is important for adaptation to altered gravity. However, the physiological limits for adaptation or the disruption of body orientation are not known. In this study, we analyzed postural changes in mice upon exposure to various low gravities. Male C57BL6/J mice (n = 6 were exposed to various gravity-deceleration conditions by customized parabolic flight-maneuvers targeting the partial-gravity levels of 0.60, 0.30, 0.15 and μ g (<0.001 g. Video recordings of postural responses were analyzed frame-by-frame by high-definition cineradiography and with exact instantaneous values of gravity and jerk. As a result, the coordinated extension of the neck, spine and hindlimbs was observed during the initial phase of gravity deceleration. Joint angles widened to 120%–200% of the reference g level, and the magnitude of the thoracic-curvature stretching was correlated with gravity and jerk, i.e., the gravity deceleration rate. A certain range of jerk facilitated mouse skeletal stretching efficiently, and a jerk of −0.3~−0.4 j (g/s induced the maximum extension of the thoracic-curvature. The postural response of animals to low gravity may undergo differential regulation by gravity and jerk.
Hasegawa, Katsuya; de Campos, Priscila S; Zeredo, Jorge L; Kumei, Yasuhiro
2014-04-24
The ability to maintain the body relative to the external environment is important for adaptation to altered gravity. However, the physiological limits for adaptation or the disruption of body orientation are not known. In this study, we analyzed postural changes in mice upon exposure to various low gravities. Male C57BL6/J mice (n = 6) were exposed to various gravity-deceleration conditions by customized parabolic flight-maneuvers targeting the partial-gravity levels of 0.60, 0.30, 0.15 and μ g (high-definition cineradiography and with exact instantaneous values of gravity and jerk. As a result, the coordinated extension of the neck, spine and hindlimbs was observed during the initial phase of gravity deceleration. Joint angles widened to 120%-200% of the reference g level, and the magnitude of the thoracic-curvature stretching was correlated with gravity and jerk, i.e., the gravity deceleration rate. A certain range of jerk facilitated mouse skeletal stretching efficiently, and a jerk of -0.3~-0.4 j (g/s) induced the maximum extension of the thoracic-curvature. The postural response of animals to low gravity may undergo differential regulation by gravity and jerk.
Earthquake prediction from China's mobile gravity data
Yiqing Zhu
2015-03-01
Full Text Available The relation between plate tectonics and earthquake evolution is analyzed systematically on the basis of 1998–2010 absolute and relative gravity data from the Crustal Movement Observation Network of China. Most earthquakes originated in the plate boundary or within the fault zone. Tectonic deformation was most intense and exhibited discontinuity within the tectonically active fault zone because of the differential movement; the stress accumulation produced an abrupt gravity change, which was further enhanced by the earthquake. The gravity data from mainland China since 2000 obviously reflected five major earthquakes (Ms > 7, all of which were better reflected than before 2000. Regional gravity anomalies and a gravity gradient change were observed in the area around the epicenter about 2 or 3 years before the earthquake occurred, suggesting that gravity change may be a seismic precursor. Furthermore, in this study, the medium-term predictions of the Ms7.3 Yutian, Ms8.0 Wenchuan, and Ms7.0 Lushan earthquakes are analytically presented and evaluated, especially to estimate location of earthquake.
Craniofacial anomalies in twins.
Keusch, C F; Mulliken, J B; Kaplan, L C
1991-01-01
Studies of twins provide insight into the relative contribution of genetic and environmental factors in the causality of structural anomalies. Thirty-five affected twin pairs were identified from a group of 1114 patients with congenital craniofacial deformities evaluated from 1972 to 1989. Forty-three of these 70 twins exhibited one or more craniofacial anomalies; these were analyzed for dysmorphic characteristics, zygosity, concordance, and family history. The anomalies were categorized into two groups: malformations and deformations. The malformations (n = 36) included hemifacial microsomia (n = 10), cleft lip and palate (n = 8), cleft palate (n = 4), rare facial cleft (n = 2), craniosynostosis (n = 2), Binder syndrome (n = 2), Treacher Collins syndrome (n = 2), craniopagus (n = 2), CHARGE association (n = 1), frontonasal dysplasia (n = 2), and constricted ears (n = 1). The deformations (n = 7) included plagiocephaly (n = 5), hemifacial hypoplasia (n = 1), and micrognathia (n = 1). Twenty-one monozygotic and 14 dizygotic twin pairs were identified. The concordance rate was 33 percent for monozygotic twins and 7 percent for dizygotic twins.(ABSTRACT TRUNCATED AT 250 WORDS)
Dimensionally reduced gravity theories are asymptotically safe
Niedermaier, Max E-mail: max@phys.univ-tours.fr
2003-11-24
4D Einstein gravity coupled to scalars and abelian gauge fields in its 2-Killing vector reduction is shown to be quasi-renormalizable to all loop orders at the expense of introducing infinitely many essential couplings. The latter can be combined into one or two functions of the 'area radius' associated with the two Killing vectors. The renormalization flow of these couplings is governed by beta functionals expressible in closed form in terms of the (one coupling) beta function of a symmetric space sigma-model. Generically the matter coupled systems are asymptotically safe, that is the flow possesses a non-trivial UV stable fixed point at which the trace anomaly vanishes. The main exception is a minimal coupling of 4D Einstein gravity to massless free scalars, in which case the scalars decouple from gravity at the fixed point.
Geoid of Nepal from airborne gravity survey
Forsberg, René; Olesen, Arne Vestergaard; Einarsson, Indriði
2011-01-01
An airborne gravity survey of Nepal was carried out December 2010 in a cooperation between DTU-Space, Nepal Survey Department, and NGA, USA. The entire country was flown with survey lines spaced 6 nm with a King Air aircraft, with a varying flight altitude from 4 to 10 km. The survey operations...... were a major challenge due to excessive jet streams at altitude as well as occasional excessive mountain waves. Despite the large 400 mGal+ range of gravity anomaly changes from the Indian plains to the Tibetan Plateau, results appear accurate to a few mGal, with proper evaluation from cross...... as well as recent GPS-heights of Mt. Everest. The new airborne data also provide an independent validation of GOCE gravity field results at the local ~100 km resolution scale....
Loop quantum gravity as an effective theory
Bojowald, Martin
2012-01-01
As a canonical and generally covariant gauge theory, loop quantum gravity requires special techniques to derive effective actions or equations. If the proper constructions are taken into account, the theory, in spite of considerable ambiguities at the dynamical level, allows for a meaningful phenomenology to be developed, by which it becomes falsifiable. The tradiational problems plaguing canonical quantum-gravity theories, such as the anomaly issue or the problem of time, can be overcome or are irrelevant at the effective level, resulting in consistent means of physical evaluations. This contribution presents aspects of canonical equations and related notions of (deformed) space-time structures and discusses implications in loop quantum gravity, such as signature change at high density from holonomy corrections, and falsifiability thanks to inverse-triad corrections.
Linker, Patrick
2016-01-01
A couple of quantum gravity theories were proposed to make theoretical predictions about the behavior of gravity. The most recent approach to quantum gravity, called E-theory, is proposed mathematical, but there is not formulated much about what dynamics of gravity this theory proposes. This research paper treats the main results of the application of E-theory to General relativity involving conservation laws and scattering of particles in presence of gravity. Also the low-energy limit of thi...
Assessment of EGM2008 using GPS/levelling and free-air gravity ...
ge
This paper carries out an initial assessment of EGM2008 over Nairobi County and its evirons using observed free-air gravity anomalies and GPS/levelling geoid undulations. ... Surveys, United Nations Geothermal Project, British Petroleum, Burmah Oil ... research. A compilation of such gravity data sets would improve geoid ...
Geoid Model and Altitude at Mount Aconcagua Region (Argentina) from Airborne Gravity Survey
Cristina Pacino, M.; Jaeger, Eric; Forsberg, René
2014-01-01
08 model. A geoid model was computed from those airborne gravity anomalies and land gravimetry data. A remove-restore method was used for terrain and global spherical harmonic reference models, with the residual gravity field signal downward continued by least-squares collocation, and the geoid...
Barriot, J. P.; Balmino, G.
1992-09-01
A novel method is presented for mapping line-of-sight gravity data (LOSGD) joining planetary probes and observers during Doppler tracking operations, with a view to geodetic and geophysical applications. LOSGD are in this case mapped as gravity anomalies along a radial direction, at constant altitude, using an inversion procedure in conjunction with a Tikhonov-Arsenine regularization method. The application of different regularization-parameter choices to a synthetic case is followed by application to the real case of Pioneer-Venus orbiter data for Venus' Gula Mons.
Gravity Fields and Interiors of the Saturnian Satellites
Rappaport, N. J.; Armstrong, J. W.; Asmar, Sami W.; Iess, L.; Tortora, P.; Somenzi, L.; Zingoni, F.
2006-01-01
This viewgraph presentation reviews the Gravity Science Objectives and accomplishments of the Cassini Radio Science Team: (1) Mass and density of icy satellites (2) Quadrupole field of Titan and Rhea (3) Dynamic Love number of Titan (4) Moment of inertia of Titan (in collaboration with the Radar Team) (5) Gravity field of Saturn. The proposed measurements for the extended tour are: (1) Quadrupole field of Enceladus (2) More accurate measurement of Titan k2 (3) Local gravity/topography correlations for Iapetus (4) Verification/disproof of "Pioneer anomaly".
Gravity and geoid model for South America
Blitzkow, Denizar; Oliveira Cancoro de Matos, Ana Cristina; do Nascimento Guimarães, Gabriel; Pacino, María Cristina; Andrés Lauría, Eduardo; Nunes, Marcelo; Castro Junior, Carlos Alberto Correia e.; Flores, Fredy; Orihuela Guevara, Nuris; Alvarez, Ruber; Napoleon Hernandez, José
2016-04-01
In the last 20 years, South America Gravity Studies (SAGS) project has undertaken an ongoing effort in establishing the fundamental gravity network (FGN); terrestrial, river and airborne relative gravity densifications; absolute gravity surveys and geoid (quasi-geoid) model computation for South America. The old FGN is being replaced progressively by new absolute measurements in different countries. In recent years, Argentina, Bolivia, Brazil, Ecuador, Paraguay and Venezuela organizations participated with relative gravity surveys. Taking advantage of the large amount of data available, GEOID2015 model was developed for 15°N and 57°S latitude and 30 ° W and 95°W longitude based on EIGEN-6C4 until degree and order 200 as a reference field. The ocean area was completed with mean free air gravity anomalies derived from DTU10 model. The short wavelength component was estimated using FFT. The global gravity field models EIGEN-6C4, DIR_R5 were used for comparison with the new model. The new geoid model has been evaluated against 1,319 GPS/BM, in which 592 are located in Brazil and the reminder in other countries. The preliminary RMS difference between GPS/BM and GEOID2015 throughout South America and in Brazil is 46 cm and 17 cm, respectively. New activities are carrying out with the support of the IGC (Geographic and Cartographic Institute) under the coordination of EPUSP/LTG and CENEGEO (Centro de Estudos de Geodesia). The new project aims to establish new gravity points with the A-10 absolute gravimeter in South America. Recent such surveys occurred in São Paulo state, Argentina and Venezuela.
Chameleon effect and the Pioneer anomaly
Anderson, John D
2012-01-01
The possibility that the apparent anomalous acceleration of the Pioneer 10 and 11 spacecraft may be due, at least in part, to a chameleon field effect is examined. A small spacecraft, with no thin shell, can have a more pronounced anomalous acceleration than a large compact body, such as a planet, having a thin shell. The chameleon effect seems to present a natural way to explain the differences seen in deviations from pure Newtonian gravity for a spacecraft and for a planet, and appears to be compatible with the basic features of the Pioneer anomaly, including the appearance of a jerk term. However, estimates of the size of the chameleon effect indicate that its contribution to the anomalous acceleration is negligible. We conclude that any inverse-square component in the anomalous acceleration is more likely caused by an unmodelled reaction force from solar-radiation pressure, rather than a chameleon field effect.
Improving compact gravity inversion using new weighting functions
Ghalehnoee, Mohammad Hossein; Ansari, Abdolhamid; Ghorbani, Ahmad
2017-01-01
We have developed a method to estimate the geometry, location and densities of anomalies coming from 2-D gravity data based on compact gravity inversion technique. Compact gravity inversion is simple, fast and user friendly but severely depends on the number of model parameters, that is, by increasing the model parameters, the anomalies tend to concentrate near the surface. To overcome this ambiguity new weighting functions based on density contrast, depth, and compactness models have been introduced. Variable compactness factors have been defined here to get either a sharp or a smooth model based on the depth of the source or existence of prior information. Depth weighting derived from one station of gravity data whereas the effect of gravity data is 2-D and 3-D. To compensate this limitation an innovating weighting function namely kernel function has been introduced which multiplies with weight and compactness matrixes to yield a general model weighting function. The method is tested using three different sets of synthetic examples: a body at various depths (20, 40, 80 and 140 m), two bodies at the same depth but various distances to estimate lateral resolution and three bodies with negative and positive density contrast in different depths. The method is also applied to three real gravity data of Woodlawn massive sulphide body, sulphides mineralization of British Colombia and iron ore body of Missouri. The method produces solutions consistent with the known geologic attributes of the gravity sources, illustrating its potential practicality.
Improving compact gravity inversion based on new weighting functions
Ghalehnoee, Mohammad Hossein; Ansari, Abdolhamid; Ghorbani, Ahmad
2016-11-01
We have developed a method to estimate the geometry, location and densities of anomalies coming from two-dimensional gravity data based on compact gravity inversion technique. Compact gravity inversion is simple, fast and user friendly but severely depends on the number of model parameters, i.e. by increasing the model parameters, the anomalies tend to concentrate near the surface. To overcome this ambiguity new weighting functions based on density contrast, depth, and compactness models have been introduced. Variable compactness factors have been defined here to get either a sharp or a smooth model based on the depth of the source or existence of prior information. Depth weighting derived from one station of gravity data whereas the effect of gravity data is two- and three-dimensional. To compensate this limitation an innovating weighting function namely kernel function has been introduced which multiplies with weight and compactness matrixes to yield a general model weighting function. The method is tested using three different sets of synthetic examples: a body at various depths (20, 40, 80 and 140 m), two bodies at the same depth but various distances to estimate lateral resolution and three bodies with negative and positive density contrast in different depths. The method is also applied to three real gravity data of Woodlawn massive sulfide body, sulfides mineralization of British Colombia and iron ore body of Missouri. The method produces solutions consistent with the known geologic attributes of the gravity sources, illustrating its potential practicality.
Gravity change and its mechanism after the first water impoundment in Three Gorges Project
SUN Shao-an; XIANG Ai-min; ZHU Ping; SHEN Chong-yang
2006-01-01
In this paper we have analyzed precise gravity survey and gravity effects resulted from water loading, crustal deformation, ground water level change and precipitation before and after the water impoundment in the Three the most significant, maximum gravity change is 200×10-8 m/s2, but this effect is limited in amplitude and range.Gravity change can be observed about 5 km offshore. The gravity change caused by ground water level change is mum gravity change is near Xiangxi. Monitoring the variation of gravity field and further study should continue in the future.
Gravity data from the San Pedro River Basin, Cochise County, Arizona
Kennedy, Jeffrey R.; Winester, Daniel
2011-01-01
The U.S. Geological Survey, Arizona Water Science Center in cooperation with the National Oceanic and Atmospheric Administration, National Geodetic Survey has collected relative and absolute gravity data at 321 stations in the San Pedro River Basin of southeastern Arizona since 2000. Data are of three types: observed gravity values and associated free-air, simple Bouguer, and complete Bouguer anomaly values, useful for subsurface-density modeling; high-precision relative-gravity surveys repeated over time, useful for aquifer-storage-change monitoring; and absolute-gravity values, useful as base stations for relative-gravity surveys and for monitoring gravity change over time. The data are compiled, without interpretation, in three spreadsheet files. Gravity values, GPS locations, and driving directions for absolute-gravity base stations are presented as National Geodetic Survey site descriptions.
Analysis of groundwater anomalies using GRACE over various districts of Jharkhand
Verma, Arpita; Kumar, Anant; Kumar, Sanjay
2016-05-01
Groundwater is an important requirement for the massive population of India. Generally the groundwater level is monitored by using monitoring wells. In this study, Gravity Recovery and Climate Experiment (GRACE) Terrestrial Water Storage (TWS), Land surface state variable GLDAS and Soil Moisture (SM) data were tested for estimating ground water information and based on these groundwater assessments were carried out over the years 2003 to 2012 for Jharkhand State. Additionally, Tropical Rainfall Measuring Mission (TRMM) accumulated rainfall data was also used for the year's 2008 to 2012.From the study over 120 months span of various districts the maximum depletion in storage of groundwater averaged over the six districts is +/-5cm/yr in the year 2010 and maximum storage year (in term of Equivalent water thickness) groundwater average over the six districts is +/-4.4cm in the year 2003. The study also utilized ground based Seasonal changes in the groundwater resource over 287 monitoring wells and estimated groundwater data using map analysis over Jharkhand. This study analyzed seasonal water level variations based on groundwater anomaly. Remote sensing generated result compared with well data shows R2 = 0.6211 and RMSE = 39.46 cm at average seasonal cycle. Also information of different time periods of rainfall (i.e., pre-monsoon and post-monsoon) was analyzed. The trend analysis of rainfall and estimated groundwater gives the basic knowledge that groundwater storage loss and gain showed similarities with increase and decrease in rainfall.
Detecting Patterns of Anomalies
2009-03-01
detect anomalies in the dataset is used in [Leung and Leckie, 2005] and [Eskin et al., 2002]. One-class SVMs [Li et al., 2003, Heller et al., 2003] and...IEE Proceedings F, 140(2): 107–113, 1993. J.D.F. Habbema, J. Hermans , and K. Vandenbroek. A stepwise discriminant analysis pro- gram using density...Technometrics, 29(4):409–412, 1987. K.A. Heller , K.M. Svore, A. Keromytis, and S.J. Stolfo. One class support vector machines for detecting anomalous
Chiral supergravity and anomalies
Mielke, E W; Macias, Alfredo; Mielke, Eckehard W.
1999-01-01
Similarily as in the Ashtekar approach, the translational Chern-Simons term is, as a generating function, instrumental for a chiral reformulation of simple (N=1) supergravity. After applying the algebraic Cartan relation between spin and torsion, the resulting canonical transformation induces not only decomposition of the gravitational fields into selfdual and antiselfdual modes, but also a splitting of the Rarita-Schwinger fields into their chiral parts in a natural way. In some detail, we also analyze the consequences for axial and chiral anomalies.
Schneider, Paul; Wagner, Christian; Zechner, Josef
This paper shows theoretically and empirically that beta- and volatility-based low risk anomalies are driven by return skewness. The empirical patterns concisely match the predictions of our model that endogenizes the role of skewness for stock returns through default risk. With increasing downside...... of betting against beta/volatility among low skew firms compared to high skew firms is economically large. Our results suggest that the returns to betting against beta or volatility do not necessarily pose asset pricing puzzles but rather that such strategies collect premia that compensate for skew risk...
Detecting Biosphere anomalies hotspots
Guanche-Garcia, Yanira; Mahecha, Miguel; Flach, Milan; Denzler, Joachim
2017-04-01
The current amount of satellite remote sensing measurements available allow for applying data-driven methods to investigate environmental processes. The detection of anomalies or abnormal events is crucial to monitor the Earth system and to analyze their impacts on ecosystems and society. By means of a combination of statistical methods, this study proposes an intuitive and efficient methodology to detect those areas that present hotspots of anomalies, i.e. higher levels of abnormal or extreme events or more severe phases during our historical records. Biosphere variables from a preliminary version of the Earth System Data Cube developed within the CAB-LAB project (http://earthsystemdatacube.net/) have been used in this study. This database comprises several atmosphere and biosphere variables expanding 11 years (2001-2011) with 8-day of temporal resolution and 0.25° of global spatial resolution. In this study, we have used 10 variables that measure the biosphere. The methodology applied to detect abnormal events follows the intuitive idea that anomalies are assumed to be time steps that are not well represented by a previously estimated statistical model [1].We combine the use of Autoregressive Moving Average (ARMA) models with a distance metric like Mahalanobis distance to detect abnormal events in multiple biosphere variables. In a first step we pre-treat the variables by removing the seasonality and normalizing them locally (μ=0,σ=1). Additionally we have regionalized the area of study into subregions of similar climate conditions, by using the Köppen climate classification. For each climate region and variable we have selected the best ARMA parameters by means of a Bayesian Criteria. Then we have obtained the residuals by comparing the fitted models with the original data. To detect the extreme residuals from the 10 variables, we have computed the Mahalanobis distance to the data's mean (Hotelling's T^2), which considers the covariance matrix of the joint
Lightman, Alan; Gingerich, Owen
1992-02-01
The present historical and methodological consideration of scientific anomalies notes that some of these are recognized as such, after long neglect, only after the emergence of compelling explanations for their presence in the given theory in view of an alternative conceptual framework. These cases of 'retrorecognition' are indicative not merely of a significant characteristic of the process of conceptual development and scientific discovery, but of the bases for such process in human psychology. Attention is given to the illustrative cases of the 'flatness problem' in big bang theory, the perigee-opposition problem in Ptolemaic astronomy, the continental-fit problem in geology, and the equality of inertial and gravitational mass.
Nardecchia, M.
2017-07-01
In December 2015, the ATLAS and CMS Collaborations presented results from data taken at the LHC with pp collisions at the center-of-mass energy of √{s} = 13{ TeV} . In the search for resonances decaying into two photons, both experiments observed a tantalising excess of events at an invariant mass of the photon pair of 750GeV. In this contribution, I will summarise some of the main phenomenological and theoretical aspects of this anomaly in terms of New Physics.
Urinary System anomalies at birth
Sharada B. Menasinkai
2015-06-01
Full Text Available Background: Congenital anomalies of urinary system are common and are found in 3-4% of population, and lethal urinary anomalies account for 10% of termination of pregnancy. Methods: A study was done to know the incidence of congenital anomalies at birth for the period of 4 months from May 99 - Sept 99 at Cheluvamba hospital attached to Mysore medical college. Congenital anomalies in the still births, live births and aborted fetuses >20 weeks were studied along with the case history and ultrasound reports. Aborted fetuses and still born babies were collected for autopsy after the consent of parents. These babies were fixed in 10% formalin and autopsy was done after fixing, and anomalies were noted. Results: Total births during study period were 3000. There were 61 babies with congenital anomalies and 6 babies had anomalies of urinary system. Among the urinary system anomalies 1 baby had bilateral renal agenesis, 1 baby had unilateral renal agenesis with anophthalmia (Fraser syndrome, 2 babies had Multicystic dysplastic kidney disease (MCDK and 1 live baby had hydronephrosis due to obstruction at pelvi ureteric junction, and 1 live female baby had polycystic kidneys. Conclusion: Incidence of urinary system anomalies in the present study was 2 per 1000 births. U/S detection of urinary anomalies varies with period of gestation, amniotic fluid volume and visualisation of urinary bladder. Autopsy helps to detect renal agenesis. [Int J Res Med Sci 2015; 3(3.000: 743-748
HUANG Motao
2016-11-01
Full Text Available Centred on the support requirement of flying track control for a long range spacecraft, a detail research is made on the computation of external disturbing gravity field, the survey accuracy of gravity anomaly on the earth' surface and the program of surveying line layout for marine gravity survey. Firstly, the solution expression of navigation error for a long range spacecraft is analyzed and modified, and the influence of the earth's gravity field on flying track of spacecraft is evaluated. Then with a given limited quota of biased error of spacecraft drop point, the accuracy requirement for calculating the external disturbing gravity field is discussed and researched. Secondly, the data truncation error and the propagated data error are studied and estimated, and the quotas of survey resolution and computation accuracy for gravity anomaly on the earth' surface are determined. Finally, based on the above quotas, a corresponding program of surveying line layout for marine gravity survey is proposed. A numerical test has been made to prove the reasonableness and validity of the suggested program.
Glacial isostatic adjustment in the static gravity field of Fennoscandia
Root, B.C.; Van der Wal, W.; Novak, P.; Ebbing, J.; Vermeersen, L.L.A.
2015-01-01
In the central part of Fennoscandia, the crust is currently rising, because of the delayed response of the viscous mantle to melting of the Late Pleistocene ice sheet. This process, called Glacial Isostatic Adjustment (GIA), causes a negative anomaly in the present-day static gravity field as isosta
QUANTIZATION DEFORMS W-INFINITY TO W-INFINITY GRAVITY
BERGSHOEFF, E; HOWE, PS; POPE, CN; SEZGIN, E; SHEN, [No Value; STELLE, KS
1991-01-01
Quantising a classical theory of w infinity gravity requires the introduction of an infinite number of counterterms in order to remove matter-dependent anomalies. We show that these counterterms correspond precisely to a renormalisation of the classical w infinity currents to quantum W(x) currents.
Gravity Disturbances at Altitude and at the Surface
Damiani, T.
2013-12-01
The U.S. National Geodetic Survey (NGS) is committed to redefining the nation's vertical datum by 2022. In support of the new vertical datum, NGS is collecting high-altitude airborne gravity data across the United States through the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project. GRAV-D (as of August 2013) has publicly released full-field gravity products from these high-altitude flights for >15% of the country. The full-field gravity (FFG) at altitude product is versatile because it allows the user to calculate any disturbance or anomaly that is appropriate for their application- based on any datum and height above the datum desired. However, conventional geophysical methods for calculating gravity disturbances assume very low altitudes above the ellipsoid. This presentation addresses the differences between several conventional and non-conventional methods for calculating gravity disturbances, from the perspective of altitudes as high as 40,000 ft. The methods for calculating a disturbance at altitude apply different corrections to the FFG for: 1. Normal gravity at the surface of the ellipsoid and the free-air reduction (1st order, 2nd order, and higher order approximations); 2. Normal gravity at the surface of the ellipsoid, upward continued to flight height; 3. Normal gravity at flight altitude above the ellipsoid from Heiskanen and Moritz (1967)'s closed equations; 4. Normal gravity at flight altitude above the ellipsoid from spherical and ellipsoidal harmonic coefficients of the ellipsoid. Initial results indicate that these methods produce gravity disturbances that are 10s of mGals different at altitude. This presentation will also investigate disturbances calculated at the surface of the ellipsoid, by downward continuing the results of the above methods. Gravity disturbances continued from airborne flight heights down to the surface are desired for comparison to terrestrial and marine gravity data.
Decomposition of gravity field and grade separation structure in Qinling-Dabie area
袁惟正; 刘寿彭; 袁学诚
1996-01-01
The regional gravity field and residual gravity anomaly in the Qinling-Dabie area were separated for the first time, which might be produced by the relief of the Moho and the inhomogeneity of crust, separately. The residual anomalies show that there are two Mesozoic subducting magmatic rocks belts. The northern belt includes West Qinling magmatic rock belt and East Qinling magmatic rock belt and extends through Nanyang Basin and dies out to the west of Fuyang. The southern belt coincides with Tongbai-Dabie area. To the west of East Qinling there is also a residual gravity low which might coincide with early Paleozoic depression.
GOCE and Future Gravity Missions for Geothermal Energy Exploitation
Pastorutti, Alberto; Braitenberg, Carla; Pivetta, Tommaso; Mariani, Patrizia
2016-08-01
Geothermal energy is a valuable renewable energy source the exploitation of which contributes to the worldwide reduction of consumption of fossil fuels oil and gas. The exploitation of geothermal energy is facilitated where the thermal gradient is higher than average leading to increased surface heat flow. Apart from the hydrologic circulation properties which depend on rock fractures and are important due to the heat transportation from the hotter layers to the surface, essential properties that increase the thermal gradient are crustal thinning and radiogenic heat producing rocks. Crustal thickness and rock composition form the link to the exploration with the satellite derived gravity field, because both induce subsurface mass changes that generate observable gravity anomalies. The recognition of gravity as a useful investigation tool for geothermal energy lead to a cooperation with ESA and the International Renewable Energy Agency (IRENA) that included the GOCE derived gravity field in the online geothermal energy investigation tool of the IRENA database. The relation between the gravity field products as the free air gravity anomaly, the Bouguer and isostatic anomalies and the heat flow values is though not straightforward and has not a unique relationship. It is complicated by the fact that it depends on the geodynamical context, on the geologic context and the age of the crustal rocks. Globally the geological context and geodynamical history of an area is known close to everywhere, so that a specific known relationship between gravity and geothermal potential can be applied. In this study we show the results of a systematic analysis of the problem, including some simulations of the key factors. The study relies on the data of GOCE and the resolution and accuracy of this satellite. We also give conclusions on the improved exploration power of a gravity mission with higher spatial resolution and reduced data error, as could be achieved in principle by flying
The Voyager Anomaly and the GEM Theory
Brandenburg, J. E.
For over a decade, the Pioneer Anomaly (PA) was an object of study and remains unresolved. Basically it is a sunward constant acceleration of the spacecraft that appeared unambiguously after the satellites passage beyond Saturn. It now appears possible the PA acceleration is the appearance of second, string-like, solution to the Einstein Equations first discussed in the context of charged finite mass charged particle potentials as part of the GEM theory. The exact solution to the metric equations is similar in form to the Schwartzchild Solution but with a positive sign: grr = (1 + rG/r)-1 where rG is a characteristic radius corresponding to the Schwartzchild radius. Adopting the approximation that for weak fields the metric becomes a Newtonian gravity potential: grr ≅-2ϕ, a string potential form is obtained in the limit grr ≅1-2ϕ, for r acceleration a ≅ c/TH = 8 x 10-10 m/sec2 in agreement with observations. The "turn on" for this potential apparently occurs with the encounter with Jupiter, which raised the spacecraft to above escape velocity. The possible physical meaning of this second metric appearance is found to be a gravitational form of Lenz's law, where objects departing from gravity potentials experience a resistance that keeps them bound at long distances.
Newtonian gravity on quantum spacetime
Majid Shahn
2014-04-01
Full Text Available The bicrossproduct model λ-Minkowski (or ‘κ-Minkowski’ quantum space-time has an anomaly for the action of the Poincaré quantum group which was resolved by an extra cotangent direction θ’ not visible classically. We show that gauging a coefficient of θ′ introduces gravity into the model. We solve and analyse the model nonrelativisticaly in a 1/r potential, finding an induced constant term in the effective potential energy and a weakening and separation of the effective gravitational and inertial masses as the test particle Klein-Gordon mass increases. The present work is intended as a proof of concept but the approach could be relevant to an understanding of dark energy and possibly to macroscopic quantum systems.
Satellite Elevation Magnetic and Gravity Models of Major South American Plate Tectonic Features
Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W.; Lidiak, E. G.; Keller, G. R. (Principal Investigator); Longacre, M. B.
1984-01-01
Some MAGSAT scalar and vector magnetic anomaly data together with regional gravity anomaly data are being used to investigate the regional tectonic features of the South American Plate. An initial step in this analysis is three dimensional modeling of magnetic and gravity anomalies of major structures such as the Andean subduction zone and the Amazon River Aulacogen at satellite elevations over an appropriate range of physical properties using Gaus-Legendre quadrature integration method. In addition, one degree average free-air gravity anomalies of South America and adjacent marine areas are projected to satellite elevations assuming a spherical Earth and available MAGSAT data are processed to obtain compatible data sets for correlation. Correlation of these data sets is enhanced by reduction of the MAGSAT data to radial polarization because of the profound effect of the variation of the magnetic inclination over South America.
P. Gasparini
1997-06-01
Full Text Available The results of about 120 magnetotelluric soundings carried out in the Vulsini, Vico and Sabatini volcanic areas were modeled along with Bouguer and aeromagnetic anomalies to reconstruct a model of the structure of the shallow (less than 5 km of depth crust. The interpretations were constrained by the information gathered from the deep boreholes drilled for geothermal exploration. MT and aeromagnetic anomalies allow the depth to the top of the sedimentary basement and the thickness of the volcanic layer to be inferred. Gravity anomalies are strongly affected by the variations of morphology of the top of the sedimentary basement, consisting of a Tertiary flysch, and of the interface with the underlying Mesozoic carbonates. Gravity data have also been used to extrapolate the thickness of the neogenic unit indicated by some boreholes. There is no evidence for other important density and susceptibility heterogeneities and deeper sources of magnetic and/or gravity anomalies in all the surveyed area.
Satellite Elevation Magnetic and Gravity Models of Major South American Plate Tectonic Features
Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W.; Lidiak, E. G.; Keller, G. R. (Principal Investigator); Longacre, M. B.
1984-01-01
Some MAGSAT scalar and vector magnetic anomaly data together with regional gravity anomaly data are being used to investigate the regional tectonic features of the South American Plate. An initial step in this analysis is three dimensional modeling of magnetic and gravity anomalies of major structures such as the Andean subduction zone and the Amazon River Aulacogen at satellite elevations over an appropriate range of physical properties using Gaus-Legendre quadrature integration method. In addition, one degree average free-air gravity anomalies of South America and adjacent marine areas are projected to satellite elevations assuming a spherical Earth and available MAGSAT data are processed to obtain compatible data sets for correlation. Correlation of these data sets is enhanced by reduction of the MAGSAT data to radial polarization because of the profound effect of the variation of the magnetic inclination over South America.
Detailed Gravity and Magnetic Survey of the Taylorsville Triassic Basin
Leftwich, John; Nowroozi, Ali, A.
1999-10-01
This work reports the progress on collecting existing gravity data in a rectangular area covering the Richmond and Taylorsville Basins and its vicinity. The area covers one-degree latitude and one degree longitude, starting at 37 North, 77 West and ending at 38 North, 78 West. Dr. David Daniels of the United State Geological Survey supplied us with more than 4900 Bouguer gravity anomalies in this area. The purpose of this report is to present the data in form of several maps and discuss its relation to the geology of the Triassic Basins and its vicinity. Johnson and others (1985) also presented a map of the Bouguer gravity anomaly of this area. However, their map covers a smaller area, and it is based on smaller number of observations.
... medlineplus.gov/ency/article/003587.htm Urine specific gravity test To use the sharing features on this page, please enable JavaScript. Urine specific gravity is a laboratory test that shows the concentration ...
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (24,284 records) were compiled by the U. S. Geological Survey. This data base was received on February 23, 1993. Principal gravity...
Northern Oklahoma Gravity Data
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (710 records) were compiled by Professor Ahern. This data base was received in June 1992. Principal gravity parameters include latitude,...
National Oceanic and Atmospheric Administration, Department of Commerce — The Central Andes gravity data (6,151 records) were compiled by Professor Gotze and the MIGRA Group. This data base was received in April, 1997. Principal gravity...
Cadiz, California Gravity Data
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (32 records) were gathered by Mr. Seth I. Gutman for AridTech Inc., Denver, Colorado using a Worden Prospector gravity meter. This data base...
Classical Weyl Transverse Gravity
Oda, Ichiro
2016-01-01
We study various classical aspects of the Weyl transverse (WTDiff) gravity in a general space-time dimension. First of all, we clarify a classical equivalence among three kinds of gravitational theories, those are, the conformally-invariant scalar tensor gravity, Einstein's general relativity and the WTDiff gravity via the gauge fixing procedure. Secondly, we show that in the WTDiff gravity the cosmological constant is a mere integration constant as in unimodular gravity, but it does not receive any radiative corrections unlike the unimodular gravity. A key point in this proof is to construct a covariantly conserved energy-momentum tensor, which is achieved on the basis of this equivalence relation. Thirdly, we demonstrate that the Noether current for the Weyl transformation is identically vanishing, thereby implying that the Weyl symmetry existing in both the conformally-invariant scalar tensor gravity and the WTDiff gravity is a "fake" symmetry. We find it possible to extend this proof to all matter fields,...
The inverse gravimetric problem in gravity modelling
Sanso, F.; Tscherning, C. C.
1989-01-01
One of the main purposes of geodesy is to determine the gravity field of the Earth in the space outside its physical surface. This purpose can be pursued without any particular knowledge of the internal density even if the exact shape of the physical surface of the Earth is not known, though this seems to entangle the two domains, as it was in the old Stoke's theory before the appearance of Molodensky's approach. Nevertheless, even when large, dense and homogeneous data sets are available, it was always recognized that subtracting from the gravity field the effect of the outer layer of the masses (topographic effect) yields a much smoother field. This is obviously more important when a sparse data set is bad so that any smoothing of the gravity field helps in interpolating between the data without raising the modeling error, this approach is generally followed because it has become very cheap in terms of computing time since the appearance of spectral techniques. The mathematical description of the Inverse Gravimetric Problem (IGP) is dominated mainly by two principles, which in loose terms can be formulated as follows: the knowledge of the external gravity field determines mainly the lateral variations of the density; and the deeper the density anomaly giving rise to a gravity anomaly, the more improperly posed is the problem of recovering the former from the latter. The statistical relation between rho and n (and its inverse) is also investigated in its general form, proving that degree cross-covariances have to be introduced to describe the behavior of rho. The problem of the simultaneous estimate of a spherical anomalous potential and of the external, topographic masses is addressed criticizing the choice of the mixed collection approach.
Casero, Roberto [Dipartimento di Fisica, Universita di Milano-Bicocca, Piazza della Scienza, 3, 20126 Milan (Italy)]. E-mail: roberto.casero@mib.infn.it; Trincherini, Enrico [Dipartimento di Fisica, Universita di Milano-Bicocca, Piazza della Scienza, 3, 20126 Milan (Italy)
2003-09-01
We study quivers in the context of matrix models. We introduce chains of generalized Konishi anomalies to write the quadratic and cubic equations that constrain the resolvents of general affine A-circumflex{sub n-1} and non-affine A{sub n} quiver gauge theories, and give a procedure to calculate all higher-order relations. For these theories we also evaluate, as functions of the resolvents, VEV's of chiral operators with two and four bi-fundamental insertions. As an example of the general procedure we explicitly consider the two simplest quivers A{sub 2} and A-circumflex{sub 1}, obtaining in the first case a cubic algebraic curve, and for the affine theory the same equation as that of U(N) theories with adjoint matter, successfully reproducing the RG cascade result. (author)
Casero, R; Casero, Roberto; Trincherini, Enrico
2003-01-01
We study quivers in the context of matrix models. We introduce chains of generalized Konishi anomalies to write the quadratic and cubic equations that constrain the resolvents of general affine and non-affine quiver gauge theories, and give a procedure to calculate all higher-order relations. For these theories we also evaluate, as functions of the resolvents, VEV's of chiral operators with two and four bifundamental insertions. As an example of the general procedure we explicitly consider the two simplest quivers A2 and A1(affine), obtaining in the first case a cubic algebraic curve, and for the affine theory the same equation as that of U(N) theories with adjoint matter, successfully reproducing the RG cascade result.
Schneider, Paul; Wagner, Christian; Zechner, Josef
risk, the standard capital asset pricing model (CAPM) increasingly overestimates expected equity returns relative to firms' true (skew-adjusted) market risk. Empirically, the profitability of betting against beta/volatility increases with firms' downside risk, and the risk-adjusted return differential...... of betting against beta/volatility among low skew firms compared to high skew firms is economically large. Our results suggest that the returns to betting against beta or volatility do not necessarily pose asset pricing puzzles but rather that such strategies collect premia that compensate for skew risk......This paper shows theoretically and empirically that beta- and volatility-based low risk anomalies are driven by return skewness. The empirical patterns concisely match the predictions of our model that endogenizes the role of skewness for stock returns through default risk. With increasing downside...
Land, K; Land, Kate; Magueijo, Joao
2004-01-01
We perform a frequentist analysis of the bispectrum of WMAP first year data. We find clear signal domination up to l=200, with overall consistency with Gaussianity except for the following features. There is a flat patch (i.e. a low chi-squared region) in the same-l components of the bispectrum spanning the range l=32-62; this may be interpreted as ruling out Gaussianity at the 99.6% confidence level. There is also an asymmetry between the North and South inter-l bispectrum components at the 99% confidence level. The preferred asymmetry axis correlates well with the (l,b)=(57,10) direction quoted in the literature for asymmetries in the power spectrum and three-point correlation function. However our analysis of the quadrupole (its bispectrum and principal axes) fail to make contact with previously claimed anomalies.
Bukley, Angie; Paloski, William; Clement, Gilles
2006-01-01
This chapter discusses potential technologies for achieving artificial gravity in a space vehicle. We begin with a series of definitions and a general description of the rotational dynamics behind the forces ultimately exerted on the human body during centrifugation, such as gravity level, gravity gradient, and Coriolis force. Human factors considerations and comfort limits associated with a rotating environment are then discussed. Finally, engineering options for designing space vehicles with artificial gravity are presented.
Terrestrial Gravity Fluctuations
Harms, Jan
2015-12-01
Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10-23 Hz-1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. 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.
Harms, Jan
2015-01-01
Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10(-23) Hz(-1/2) above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. 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
Jan Harms
2015-12-01
Full Text Available Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10^–23 Hz^–1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. 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
Terrestrial Gravity Fluctuations
Harms, Jan
2015-01-01
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.
Bergshoeff, E.; Pope, C.N.; Stelle, K.S.
1990-01-01
We discuss the notion of higher-spin covariance in w∞ gravity. We show how a recently proposed covariant w∞ gravity action can be obtained from non-chiral w∞ gravity by making field redefinitions that introduce new gauge-field components with corresponding new gauge transformations.
Maximum Autocorrelation Factorial Kriging
Nielsen, Allan Aasbjerg; Conradsen, Knut; Pedersen, John L.; Steenfelt, Agnete
2000-01-01
This paper describes maximum autocorrelation factor (MAF) analysis, maximum autocorrelation factorial kriging, and its application to irregularly sampled stream sediment geochemical data from South Greenland. Kriged MAF images are compared with kriged images of varimax rotated factors from an ordinary non-spatial factor analysis, and they are interpreted in a geological context. It is demonstrated that MAF analysis contrary to ordinary non-spatial factor analysis gives an objective discrimina...
The standard model with gravity couplings
Chang, L N; Lay Nam Chang; Chopin Soo
1996-01-01
ABSTRACT-The Standard Model with Gravity Couplings-Lay Nam Chang(Virginia Tech) & Chopin Soo(Penn State)--- It has been shown by Ashtekar, and many others after him, that classical gravity in four dimensions can be described equally well by (anti)self-dual variables instead of the conventional variables. In this paper, we examine the coupling of matter fields to gravity from this perspective, and show that the known quark and lepton multiplets in the Standard Model of particle physics can be introduced into the theory in a manner which ensures the cancellation of perturbative chiral gauge anomalies, despite the fact that the the Ashtekar-Sen connection allows for couplings only to left-handed Weyl fermions. We also explore a global anomaly associated with the theory, and argue that its removal requires that the number of fundamental fermions in the theory must be multiples of 16. In addition, we investigate the behavior of the theory under discrete transformations P, C and T, and discuss possible violatio...
Induced Gravity II: Grand Unification
Einhorn, Martin B
2016-01-01
As an illustration of a renormalizable, asymptotically-free model of induced gravity, we consider an $SO(10)$ gauge theory interacting with a real scalar multiplet in the adjoint representation. We show that dimensional transmutation can occur, spontaneously breaking $SO(10)$ to $SU(5){\\otimes}U(1),$ while inducing the Planck mass and a positive cosmological constant, all proportional to the same scale $v$. All mass ratios are functions of the values of coupling constants at that scale. Below this scale (at which the Big Bang may occur), the model takes the usual form of Einstein-Hilbert gravity in de Sitter space plus calculable corrections. We show that there exist regions of parameter space in which the breaking results in a local minimum of the effective action, and a {\\bf positive} dilaton $(\\hbox{mass})^2$ from two-loop corrections associated with the conformal anomaly. Furthermore, unlike the singlet case we considered previously, some minima lie within the basin of attraction of the ultraviolet fixed ...
Anita Thea Saraswati
2015-02-01
Full Text Available Aktivitas tektonik yang terjadi di bumi merupakan hal yang masih terus diteliti sampai sekarang. Sumatera yang terletak pada area Sunda Megathrust, yang merupakan zona subduksi Lempeng Indo-Australia dan Lempeng Eurasia, mengakibatkan daerah ini rentan dengan aktivitas seismogenic. Salah satu akibat dari adanya pergerakan kedua lempeng ini adalah terbentuknya tatanan tektonik di wilayah Sumatera. GOCE (Gravity field and steady-state Ocean Circulation Explorer menawarkan metode yang cepat dengan cakupan global untuk mendapatkan data gayaberat bumi. Dengan memanfaatkan hitungan dari spherical harmonic coeffisien (SHC serta dilengkapi dengan data Digital Elevation Model (DEM, dapat diketahui nilai anomali gayaberat pada suatu wilayah. Distribusi anomali gayaberat mampu mencerminkan kondisi tektonik di suatu area. Variasi spasial dari anomali gayaberat menunjukkan bahwa pada palung yang terbentuk akibat subduksi kedua lempeng memiliki nilai anomali gayaberat negatif dengan nilai rata-rata sebesar -42.8729 mgal. Forearc ridge yang terbentuk akibat konvergensi lempeng memiliki nilai anomali gayaberat positif, sedangkan forearc basin yang merupakan cekungan diantara backarc dan forearc ridge, memiliki nilai anomali gayaberat negatif yang lebih kuat daripada yang terdapat pada Sunda Megathrust. Variasi temporal yang teramati menunjukkan bahwa distribusi anomali gayaberat positif yang terdapat pada prisma akresi di kedua tepian palung bergerak semakin mendekati Sunda Megathrust pada tiap seri pengamatannya, sedangkan distribusi anomali gayaberat negatif pada palung laut dan forearc basin membentuk suatu pola distribusi yang semakin menyempit sehingga menyebabkan semakin curamnya gradient anomali gayaberat pada area di sekitarnya.
Gravity modelling of the Ramadas Caldera (Argentinean Puna, central Andes)
Casas, A. [Barcelona Univ. (Spain). Facultad de Geologia; Hernandez, E.; Marti, J. [Consejo Superior de Investigaciones Cientificas, Barcelona (Spain). Inst. de Ciencias de la Terra Jaume Almera; Petrinovic, I. [Universidad Nacional de Salta (Argentina)
1995-12-31
In order to identify and characterize the event area of abundant Upper Miocene proximal rhyolitic pyroclastic deposits and extrusive domes which concentrate in the Ramadas area, near Sant`Antonio de los Cobres (Salta) at the Puna Altiplano (Central Andes), a detailed gravity survey has been carried out. Regional Bouguer gravity data were augmented with new 173 gravity observations measured sufficiently close-spaced to resolve the short wavelength produced by the structure of interest. Besides, the geophysical survey was done in conjunction with geologic and geochemical studies which were critically important to our interpretation. After the separation of the regional trend, the residual anomaly map displays a circular gravity low reaching-80 m Gal centered over scarce outcrops of rhyolitic and pyroclastic. This gravity low is interpreted as produced by block subsidence along ring fractures during eruption and/or deflation of the chamber. As the accumulation of thick, low density rock types in the zone of collapse is responsible of the prominent negative gravity anomalies, them has been used to estimated the thickness of caldera infill. (author). 8 refs., 4 figs
Algebraic study of chiral anomalies
Juan Mañes; Raymond Stora; Bruno Zumino
2012-06-01
The algebraic structure of chiral anomalies is made globally valid on non-trivial bundles by the introduction of a ﬁxed background connection. Some of the techniques used in the study of the anomaly are improved or generalized, including a systematic way of generating towers of ‘descent equations’.
Anomaly mediation deformed by axion
Nakayama, Kazunori, E-mail: kazunori@hep-th.phys.s.u-tokyo.ac.jp [Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8583 (Japan); Yanagida, Tsutomu T. [Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8583 (Japan)
2013-05-13
We show that in supersymmetric axion models the axion supermultiplet obtains a sizable F-term due to a non-supersymmetric dynamics and it generally gives the gaugino masses comparable to the anomaly mediation contribution. Thus the gaugino mass relation predicted by the anomaly mediation effect can be significantly modified in the presence of axion to solve the strong CP problem.
Cassez, Franck; Hansen, Rene Rydhof; Olesen, Mads Chr.
2012-01-01
Timing anomalies make worst-case execution time analysis much harder, because the analysis will have to consider all local choices. It has been widely recognised that certain hardware features are timing anomalous, while others are not. However, defining formally what a timing anomaly is, has bee...
Seismic data fusion anomaly detection
Harrity, Kyle; Blasch, Erik; Alford, Mark; Ezekiel, Soundararajan; Ferris, David
2014-06-01
Detecting anomalies in non-stationary signals has valuable applications in many fields including medicine and meteorology. These include uses such as identifying possible heart conditions from an Electrocardiography (ECG) signals or predicting earthquakes via seismographic data. Over the many choices of anomaly detection algorithms, it is important to compare possible methods. In this paper, we examine and compare two approaches to anomaly detection and see how data fusion methods may improve performance. The first approach involves using an artificial neural network (ANN) to detect anomalies in a wavelet de-noised signal. The other method uses a perspective neural network (PNN) to analyze an arbitrary number of "perspectives" or transformations of the observed signal for anomalies. Possible perspectives may include wavelet de-noising, Fourier transform, peak-filtering, etc.. In order to evaluate these techniques via signal fusion metrics, we must apply signal preprocessing techniques such as de-noising methods to the original signal and then use a neural network to find anomalies in the generated signal. From this secondary result it is possible to use data fusion techniques that can be evaluated via existing data fusion metrics for single and multiple perspectives. The result will show which anomaly detection method, according to the metrics, is better suited overall for anomaly detection applications. The method used in this study could be applied to compare other signal processing algorithms.
Yuan, Bingqiang; Zhang, Huaan; Zhang, Chunguan; Xu, Haihong; Yan, Yunkui
2016-04-01
In order to perform gas exploration and determine the distribution pattern of gas in the Yanchang Oil Field in the eastern part of the North Shaanxi Slope, Ordos Basin, China, gravity and magnetic survey data were systemically collated, processed and interpreted in combination with the drilling data and recent seismic data. The genesis of gravity and magnetic anomalies and the relationship between the characteristics of the gravity and magnetic fields and known gas distribution were explored in order to predict the favourable exploration targets for gas. Gravity anomalies resulted both from the lateral variation in density of the basement rock and lateral lithologic transformation in the sedimentary cover. The regional magnetic anomalies were mainly caused by the basement metamorphic rocks and the residual magnetic anomalies may reflect the amount and general location of the volcanic materials in the overlying strata. The residual gravity and magnetic anomalies generated by high-density sandstone and high content of volcanics in the gas reservoir of the upper Paleozoic distorted and deformed the anomaly curves when they were stacked onto the primary background anomaly. The gas wells were generally found to be located in the anomaly gradient zones, or the distorted part of contour lines, and the flanks of high and low anomalies, or the transitional zones between anomaly highs and lows. The characteristics of gravity and magnetic fields provide significant information that can be used for guidance when exploring the distribution of gas. Based on these characteristics, five favourable areas for gas exploration were identified; these are quasi-equally spaced like a strip extending from the southeast to the northwest.
Regional Gravity Field Modeling with Abel-Poisson Radial Basis Functions
MA Zhiwei
2016-09-01
Full Text Available With the increasing number of various types of high-resolution gravity observations, earth gravity models can be regionally refined. We use Abel-Poisson kernel to represent the gravity as the linear summation of finite radial basis functions and combine the multiple gravity data to build a regional gravity model with high resolution. The minimum root mean square criterion based on the data adaptive algorithm is proposed to calculate the base function, which promote the speed of computation significantly. Taking the central South China Sea as an example, two different types of gravity data, namely geoid undulations with resolution of 6'×6' and gravity anomaly with resolution of 2'×2', are used to construct the high-resolution regional gravity model. The model has a resolution of 2'×2', and has a great agreement with original gravity anomaly, reaching to ±0.8×10-5m/s2.Our results show that using radial basis functions to construct the regional gravity field can avoid the problem of slow convergence of spherical harmonic functions, and can improve the resolution remarkably.
Geophysical Analysis of Major Geothermal Anomalies in Romania
Panea, Ionelia; Mocanu, Victor
2017-07-01
The Romanian segment of the Eastern Pannonian Basin and the Moesian Platform are known for their geothermal and hydrocarbon-bearing structures. We used seismic, gravity, and geothermal data to analyze the geothermal behavior in the Oradea and Timisoara areas, from the Romanian segment of Eastern Pannonian Basin, and the Craiova-Bals-Optasi area, from the Moesian Platform. We processed 22 seismic reflection data sets recorded in the Oradea and Timisoara areas to obtain P-wave velocity distributions and time seismic sections. The P-wave velocity distributions correlate well with the structural trends observed along the seismic lines. We observed a good correlation between the high areas of crystalline basement seen on the time seismic sections and the high heat flow and gravity-anomaly values. For the Craiova-Bals-Optasi area, we computed a three-dimensional (3D) temperature model using calculated and measured temperature and geothermal gradient values in wells with an irregular distribution on the territory. The high temperatures from the Craiova-Bals-Optasi area correlate very well with the uplifted basement blocks seen on the time seismic sections and high gravity-anomaly values.
Establishment of National Gravity Base Network of Iran
Hatam Chavari, Y.; Bayer, R.; Hinderer, J.; Ghazavi, K.; Sedighi, M.; Luck, B.; Djamour, Y.; Le Moign, N.; Saadat, R.; Cheraghi, H.
2009-04-01
upward movement of lava. g. Producing precise mean gravity anomaly for precise geoid determination. Replacing precise spirit leveling by the GPS leveling using precise geoid model is one of the forth coming application of the precise geoid. A gravity base network of 28 stations established over Iran. The stations were built mainly at bedrocks. All stations were measured by an FG5 absolute gravimeter, at least 12 hours at each station, to obtain an accuracy of a few micro gals. Several stations were repeated several times during recent years to estimate the gravity changes.
Quantization of Emergent Gravity
Yang, Hyun Seok
2013-01-01
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.
Quantization of emergent gravity
Yang, Hyun Seok
2015-02-01
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 space-time admits a symplectic structure, in other words, a microscopic space-time becomes noncommutative (NC). If gravity emerges from U(1) gauge theory on NC space-time, this picture of emergent gravity suggests a completely new quantization scheme where quantum gravity is defined by quantizing space-time itself, leading to a dynamical NC space-time. 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 space-time and matter fields are equally emergent from a universal vacuum of quantum gravity.
Anomaly Mediation and Cosmology
Basboll, A; Jones, D R T
2011-01-01
We consider an extension of the MSSM wherein anomaly mediation is the source of supersymmetry-breaking, and the tachyonic slepton problem is solved by a Fayet-Iliopoulos (FI) $D$-term associated with an additional $U(1)$ symmetry, which also facilitates the see-saw mechanism for neutrino masses and a natural source for the Higgs $\\mu$-term. We explore the cosmological consequences of the model, showing that the model naturally produces a period of hybrid inflation, terminating in the production of cosmic strings. In spite of the presence of a $U(1)$ with an FI term, inflation is effected by the $F$-term, with a $D$-flat tree potential (the FI term being cancelled by non-zero squark and slepton fields). Calculating the 1-loop corrections to the inflaton potential, we estimate the constraints on the parameters of the model from Cosmic Microwave Background data. We briefly discuss the mechanisms for baryogenesis via conventional leptogenesis, the out-of-equilibrium production of neutrinos from the cosmic strings...
Kinsland, G L; Hurtado, M; Pope, K O
2000-04-15
Small negative gravity anomalies are found in gravity data from along the northwestern shoreline of the Yucatan Peninsula. These anomalies are shown to be due to elongate, shallow anomalous porosity zones in the Tertiary carbonates. These zones are caused primarily by groundwater solution and are presently active conduits for groundwater flow. The association of these small gravity anomalies with known topographic and structural features of the area, which partially overlies the Chicxulub Impact crater, indicates their development was influenced by structures, faults and/or fractures, within the Tertiary and pre-Tertiary carbonates.
Kinsland, G. L.; Hurtado, M.; Pope, K. O.; Ocampo, A. C. (Principal Investigator)
2000-01-01
Small negative gravity anomalies are found in gravity data from along the northwestern shoreline of the Yucatan Peninsula. These anomalies are shown to be due to elongate, shallow anomalous porosity zones in the Tertiary carbonates. These zones are caused primarily by groundwater solution and are presently active conduits for groundwater flow. The association of these small gravity anomalies with known topographic and structural features of the area, which partially overlies the Chicxulub Impact crater, indicates their development was influenced by structures, faults and/or fractures, within the Tertiary and pre-Tertiary carbonates.
Thermal anomaly at the Earth's surface associated with a lava tube
Piombo, Antonello; Di Bari, Marco; Tallarico, Andrea; Dragoni, Michele
2016-10-01
Lava tubes are frequently encountered in volcanic areas. The formation of lava tubes has strong implications on the volcanic hazard during effusive eruptions. The thermal dissipation of lava flowing in a tube is reduced in respect to the lava flowing in an open channel so the lava may threaten areas that would not be reached by flows in open channels: for this reason it is important to detect the presence of lava tubes. In this work we propose a model to detect the presence and the characteristics of lava tubes by their thermal footprint at the surface. We model numerically the temperature distribution and the heat flow, both in the steady and the transient state, and we take into account the principal thermal effects due to the presence of an active lava tube, i.e. the conduction to the ground and the atmosphere, the convection and the radiation in the atmosphere. We assume that lava fluid is at high temperature, in motion inside a sloping tube under the gravity force. The thermal profile across the tube direction, in particular the width of the temperature curve, allows to evaluate the depth of the tube. The values of maximum temperature and of tube depth allow to estimate the area of the tube section. The shape of the temperature curve and its asymmetry can give information about the geometry of the tube. If we observe volcanic areas at different times by thermal cameras, we can detect anomalies and evaluate their causes during an eruption; in particular, we can evaluate whether they are due to active lava flows or not and what is their state. For lava tubes, we can connect thermal anomalies with lava tube position, characteristics and state.
Maximum likely scale estimation
Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo
2005-01-01
A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and/or ...
Subduction zones seen by GOCE gravity gradients
Švarc, Mario; Herceg, Matija; Cammarano, Fabio
and used as starting point for analysis based on image processing. On obtained maps, locations of known subduction zones were represented with characteristic elongated patterns and cross-sections. Cross sections of well-known subduction zones were used as input patterns for pattern recognition method....... Few pattern recognition methods were tested on all 6 gravity gradient tensor components represented as global scale maps with resolution of 100km (corresponds to the resolution of the GOCE satellite data). By adjusting pattern recognition methods’ features and optimizing various input patterns......, the best method was applied. That is a combination of methods based on SURF (Speeded Up Robust Features) and MSER (Maximally Stable Extremal Regions) algorithms provided in MATLAB’s Computer Vision System Toolbox. Based on 6 gravity gradient components, the global gradient anomaly maps were produced...
The GRADIO spaceborne gravity gradiometer: Development and accommodation
Bernard, A.
1989-06-01
The European ARISTOTELES mission aims at the determination of the Earth's gravity field at short wavelength with a global coverage. Gravity gradient measurements will be achieved during six months by the GRADIO instrument onboard a dedicated satellite in a near dawn-dusk sun-synchronous orbit at an altitude of 200 km. The objective is an accuracy of better than 5 mgals for gravity anomalies, at ground level for blocks of 1 x 1 deg. According to present knowledge of the potential, the recovery of higher spherical harmonics (degree and order greater than 30) is of main importance. This leads to focus on the variations of the measured components T(sub ij) of the gravity gradient tensor, at frequencies greater than 5 x 10(exp -3) Hz. The resolution, required for the gradiometer is 10(exp -2) Eotvos (i.e., 10(exp -11)/s squared) with an averaging time of 4 s.
A Study on the Compatibility of 3-D Seismic Velocity Structures with Gravity Data of Taiwan
Horng-Yuan Yen and Hsien-Hsiang Hsieh
2010-01-01
Full Text Available The Bouguer anomaly of Taiwan has been revised in this study based on more accurate terrain data provided by the Taiwanese Digital Terrain Model compiled by the Taiwan Forestry Bureau. Three seismic velocity models, those determined by Rau and Wu (1995, Kim et al. (2005, and Wu et al. (2007 respectively, were selected for our study. We converted their velocity models to density models using the relationship between P-wave velocity and rock density proposed by Ludwig et al. (1970 and Barton (1986, and then calculated their corresponding gravity anomalies. According to the correlation coefficient between the Bouguer anomalies calculated from the velocity models and the revised Bouguer anomalies, the Kim et al. model was more compatible with gravity data than the other two velocity models. The differences between the revised gravity anomaly and the calculated gravity anomalies trend toward positive values at elevations higher than 2000 m. This indicates that the velocities at the shallower depths beneath the mountainous area of the three models are overdetermined, i.e., higher than the real velocities. This ratiocination implies that the crustal thickness beneath the Central Range is less than 55 km which was obtained from the velocity models.
Symplectic Structure of Intrinsic Time Gravity
Eyo Eyo Ita
2016-08-01
Full Text Available The Poisson structure of intrinsic time gravity is analysed. With the starting point comprising a unimodular three-metric with traceless momentum, a trace-induced anomaly results upon quantization. This leads to a revision of the choice of momentum variable to the (mixed index traceless momentric. This latter choice unitarily implements the fundamental commutation relations, which now take on the form of an affine algebra with SU(3 Lie algebra amongst the momentric variables. The resulting relations unitarily implement tracelessness upon quantization. The associated Poisson brackets and Hamiltonian dynamics are studied.
Ensemble average theory of gravity
Khosravi, Nima
2016-12-01
We put forward the idea that all the theoretically consistent models of gravity have contributions to the observed gravity interaction. In this formulation, each model comes with its own Euclidean path-integral weight where general relativity (GR) has automatically the maximum weight in high-curvature regions. We employ this idea in the framework of Lovelock models and show that in four dimensions the result is a specific form of the f (R ,G ) model. This specific f (R ,G ) satisfies the stability conditions and possesses self-accelerating solutions. Our model is consistent with the local tests of gravity since its behavior is the same as in GR for the high-curvature regime. In the low-curvature regime the gravitational force is weaker than in GR, which can be interpreted as the existence of a repulsive fifth force for very large scales. Interestingly, there is an intermediate-curvature regime where the gravitational force is stronger in our model compared to GR. The different behavior of our model in comparison with GR in both low- and intermediate-curvature regimes makes it observationally distinguishable from Λ CDM .
Invariant regularization of anomaly-free chiral theories
Chang, L N; Chang, Lay Nam; Soo, Chopin
1997-01-01
We present a generalization of the Frolov-Slavnov invariant regularization scheme for chiral fermion theories in curved spacetimes. The Lagrangian level regularization is explicitly invariant under all the local gauge symmetries of the theory, including local Lorentz invariance. The perturbative scheme works for {\\it arbitrary} representations which satisfy the chiral gauge anomaly and mixed Lorentz-gauge anomaly cancellation conditions. Anomalous theories on the other hand manifest themselves by having divergent fermion loops which remain unregularized by the scheme. Since the invariant scheme is promoted to also include local Lorentz invariance, spectator fields which do not couple to gravity cannot be, and are not, introduced. Furthermore, the scheme is truly Weyl(chiral) in that {\\it all} fields, including the regulators, are left-handed; and {\\it only the left-handed spin connection} is needed. The scheme is therefore well-suited for the perturbative study of all four known forces in a completely chiral ...
The flyby anomaly: A case for strong gravitomagnetism ?
Acedo, L
2015-01-01
In the last two decades an anomalous variation in the asymptotic velocity of spacecraft performing a flyby manoeuvre around Earth has been discovered through careful Doppler tracking and orbital analysis. No viable hypothesis for a conventional explanation of this effect has been proposed and its origin remains unexplained. In this paper we discuss a strong transversal component of the gravitomagnetic field as a possible source of the flyby anomaly. We show that the perturbations induced by such a field could fit the anomalies both in sign and order of magnitude. But, although the secular contributions to the Gravity Probe B experimental results and the Lense-Thirring effect in geodynamics satellites can be made null, the detailed orbital evolution is easily in conflict with such an enhanced gravitomagnetic effect.
Anomaly induced transport coefficients, from weak to strong coupling
Pena-Benitez, Francisco
2013-01-01
The existence of new transport phenomena associated to the presence of quantum anomalies has atracted very recently the attention of theorist. These transport coefficient have very interesting properties, for example, they do not renormalize. The most famous case of anomaly induced transport phenomena is the Chiral Magnetic Effect, in which an electric current is produced by a magnetic field if the system has a different number of right handed fermions respect the left handed one. In this thesis we have studied those transport coefficients from Kubo formulas at weak and strong coupling. To finish a fluid/gravity approach is used to compute all the second order anomalous coefficients in an anomalous conformal fluid.
Shoberg, Thomas G.; Stoddard, Paul R.
2013-01-01
The ability to augment local gravity surveys with additional gravity stations from easily accessible national databases can greatly increase the areal coverage and spatial resolution of a survey. It is, however, necessary to integrate such data seamlessly with the local survey. One challenge to overcome in integrating data from national databases is that these data are typically of unknown quality. This study presents a procedure for the evaluation and seamless integration of gravity data of unknown quality from a national database with data from a local Global Positioning System (GPS)-based survey. The starting components include the latitude, longitude, elevation and observed gravity at each station location. Interpolated surfaces of the complete Bouguer anomaly are used as a means of quality control and comparison. The result is an integrated dataset of varying quality with many stations having GPS accuracy and other reliable stations of unknown origin, yielding a wider coverage and greater spatial resolution than either survey alone.
Processing MAGSAT data for comparison with geoid anomalies
Bowin, C. O. (Principal Investigator)
1982-01-01
A digital data library of MAGSAT data consisting of 1,615,636 measurements from the quiet data set, is geographically sorted, and allows rapid analysis and processing of all the quiet magnetic data about any selected location. Because this library of MAGSAT data is compatible with existing gravity and geoid data library processing and display system software, correlations between MAGSAT, surface gravity, GEOS-3 radar altimeter geoid and bathymetric data sets can be conveniently detected and analyzed. Polynomial trends from each half-orbit were removed as an effective way of estimating and removing ring current effects following estimation of the core field contribution. It was found that a third order polynomial is the lowest polynomial order that appears to provide the best consistency of residual anomalies between coincident orbits.
The cosmological constant as a manifestation of the conformal anomaly?
Thomas, Evan C; Zhitnitsky, Ariel R
2009-01-01
We propose that the solution to the cosmological vacuum energy puzzle may come from the infrared sector of the effective theory of gravity, where the impact of the trace anomaly is of upmost relevance. We proceed by introducing two auxiliary fields, which are capable of describing a diversity of quantum states via specification of their macroscopic (IR) boundary conditions, in contrast to ultraviolet quantum effects. Our investigation aims at finding a realistic cosmological solution which interprets the observed cosmological constant as a well defined deficit in the zero point energy density of the Universe. The energy density arises from a phase transition, which alters the properties of the quantum ground state. We explicitly formulate low energy gravity as an effective field theory with a precise definition of the "point of normalization" as the point at which the "renormalized cosmological constant" is set to zero in the Minkowski vacuum, in which the Einstein equations are automatically satisfied as the...
Maximum information photoelectron metrology
Hockett, P; Wollenhaupt, M; Baumert, T
2015-01-01
Photoelectron interferograms, manifested in photoelectron angular distributions (PADs), are a high-information, coherent observable. In order to obtain the maximum information from angle-resolved photoionization experiments it is desirable to record the full, 3D, photoelectron momentum distribution. Here we apply tomographic reconstruction techniques to obtain such 3D distributions from multiphoton ionization of potassium atoms, and fully analyse the energy and angular content of the 3D data. The PADs obtained as a function of energy indicate good agreement with previous 2D data and detailed analysis [Hockett et. al., Phys. Rev. Lett. 112, 223001 (2014)] over the main spectral features, but also indicate unexpected symmetry-breaking in certain regions of momentum space, thus revealing additional continuum interferences which cannot otherwise be observed. These observations reflect the presence of additional ionization pathways and, most generally, illustrate the power of maximum information measurements of th...
ALP hints from cooling anomalies
Giannotti, Maurizio
2015-01-01
We review the current status of the anomalies in stellar cooling and argue that, among the new physics candidates, an axion-like particle would represent the best option to account for the hinted additional cooling.
Notes on Anomaly Induced Transport
Landsteiner, Karl
2016-01-01
Chiral anomalies give rise to dissipationless transport phenomena such as the chiral magnetic and vortical effects. In these notes I review the theory from a quantum field theoretic, hydrodynamic and holographic perspective. A physical interpretation of the otherwise somewhat obscure concepts of consistent and covariant anomalies will be given. Vanishing of the CME in strict equilibrium will be connected to the boundary conditions in momentum space imposed by the regularization. The role of the gravitational anomaly will be explained. That it contributes to transport in an unexpectedly low order in the derivative expansion can be easiest understood via holography. Anomalous transport is supposed to play also a key role in understanding the electronics of advanced materials, the Dirac- and Weyl (semi)metals. Anomaly related phenomena such as negative magnetoresistivity, anomalous Hall effect, thermal anomalous Hall effect and Fermi arcs can be understood via anomalous transport. Finally I briefly review a holo...
Eddington's theory of gravity and its progeny.
Bañados, Máximo; Ferreira, Pedro G
2010-07-01
We resurrect Eddington's proposal for the gravitational action in the presence of a cosmological constant and extend it to include matter fields. We show that the Newton-Poisson equation is modified in the presence of sources and that charged black holes show great similarities with those arising in Born-Infeld electrodynamics coupled to gravity. When we consider homogeneous and isotropic space-times, we find that there is a minimum length (and maximum density) at early times, clearly pointing to an alternative theory of the big bang. We thus argue that the modern formulation of Eddington's theory, Born-Infeld gravity, presents us with a novel, nonsingular description of the Universe.
Pirkola, Patrik
2016-01-01
The surface gravity on Mars is smaller than the surface gravity on Earth, resulting in longer falling times. This effect can be simulated on Earth by taking advantage of air resistance and buoyancy, which cause low density objects to fall slowly enough to approximate objects falling on the surface of Mars. We describe a computer simulation based on an experiment that approximates Martian gravity, and verify our numerical results by performing the experiment.
Rongjia Yang
2014-08-01
Full Text Available If we assume that the source of thermodynamic system, ρ and p, are also the source of gravity, then either thermal quantities, such as entropy, temperature, and chemical potential, can induce gravitational effects, or gravity can induce thermal effects. We find that gravity can be seen as entropic force only for systems with constant temperature and zero chemical potential. The case for Newtonian approximation is discussed.
Trugenberger, Carlo A
2016-01-01
In a recently developed approach, geometry is modelled as an emergent property of random networks. Here I show that one of these models I proposed is exactly quantum gravity defined in terms of the combinatorial Ricci curvature recently derived by Ollivier. Geometry in the weak (classical) gravity regime arises in a phase transition driven by the condensation of short graph cycles. The strong (quantum) gravity regime corresponds to "small world" random graphs with logarithmic distance scaling.
Renormalization group flows and anomalies
Komargodski, Zohar
2015-01-01
This chapter reviews various aspects of renormalization group flows and anomalies. The chapter considers specific Euclidean two-dimensional theories. Namely, the theories are invariant under translations and rotations in the two space directions. Here the chapter studies theories where, if possible, certain equations hold in fact also at coincident points. In other words, the chapter looks at theories where there is no local gravitational anomaly.
Situs anomalies on prenatal MRI.
Nemec, Stefan F; Brugger, Peter C; Nemec, Ursula; Bettelheim, Dieter; Kasprian, Gregor; Amann, Gabriele; Rimoin, David L; Graham, John M; Prayer, Daniela
2012-04-01
Situs anomalies refer to an abnormal organ arrangement, which may be associated with severe errors of development. Due regard being given to prenatal magnetic resonance imaging (MRI) as an adjunct to ultrasonography (US), this study sought to demonstrate the in utero visualization of situs anomalies on MRI, compared to US. This retrospective study included 12 fetuses with situs anomalies depicted on fetal MRI using prenatal US as a comparison modality. With an MRI standard protocol, the whole fetus was assessed for anomalies, with regard to the position and morphology of the following structures: heart; venous drainage and aorta; stomach and intestines; liver and gallbladder; and the presence and number of spleens. Situs inversus totalis was found in 3/12 fetuses; situs inversus with levocardia in 1/12 fetuses; situs inversus abdominis in 2/12 fetuses; situs ambiguous with polysplenia in 3/12 fetuses, and with asplenia in 2/12 fetuses; and isolated dextrocardia in 1/12 fetuses. Congenital heart defects (CHDs), vascular anomalies, and intestinal malrotations were the most frequent associated malformations. In 5/12 cases, the US and MRI diagnoses were concordant. Compared to US, in 7/12 cases, additional MRI findings specified the situs anomaly, but CHDs were only partially visualized in six cases. Our initial MRI results demonstrate the visualization of situs anomalies and associated malformations in utero, which may provide important information for perinatal management. Using a standard protocol, MRI may identify additional findings, compared to US, which confirm and specify the situs anomaly, but, with limited MRI visualization of fetal CHDs. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Anomaly detection on cup anemometers
Vega, Enrique; Pindado, Santiago; Martínez, Alejandro; Meseguer, Encarnación; García, Luis
2014-12-01
The performances of two rotor-damaged commercial anemometers (Vector Instruments A100 LK) were studied. The calibration results (i.e. the transfer function) were very linear, the aerodynamic behavior being more efficient than the one shown by both anemometers equipped with undamaged rotors. No detection of the anomaly (the rotors’ damage) was possible based on the calibration results. However, the Fourier analysis clearly revealed this anomaly.
Gravity Independent Compressor Project
National Aeronautics and Space Administration — We propose to develop and demonstrate a small, gravity independent, vapor compression refrigeration system using a linear motor compressor which effectively...
Classical Weyl transverse gravity
Oda, Ichiro [University of the Ryukyus, Department of Physics, Faculty of Science, Nishihara, Okinawa (Japan)
2017-05-15
We study various classical aspects of the Weyl transverse (WTDiff) gravity in a general space-time dimension. First of all, we clarify a classical equivalence among three kinds of gravitational theories, those are, the conformally invariant scalar tensor gravity, Einstein's general relativity and the WTDiff gravity via the gauge-fixing procedure. Secondly, we show that in the WTDiff gravity the cosmological constant is a mere integration constant as in unimodular gravity, but it does not receive any radiative corrections unlike the unimodular gravity. A key point in this proof is to construct a covariantly conserved energy-momentum tensor, which is achieved on the basis of this equivalence relation. Thirdly, we demonstrate that the Noether current for the Weyl transformation is identically vanishing, thereby implying that the Weyl symmetry existing in both the conformally invariant scalar tensor gravity and the WTDiff gravity is a ''fake'' symmetry. We find it possible to extend this proof to all matter fields, i.e. the Weyl-invariant scalar, vector and spinor fields. Fourthly, it is explicitly shown that in the WTDiff gravity the Schwarzschild black hole metric and a charged black hole one are classical solutions to the equations of motion only when they are expressed in the Cartesian coordinate system. Finally, we consider the Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmology and provide some exact solutions. (orig.)
Animesh Mukherjee
1991-01-01
Full Text Available Based upon Biot's [1965] theory of initial stresses of hydrostatic nature produced by the effect of gravity, a study is made of surface waves in higher order visco-elastic media under the influence of gravity. The equation for the wave velocity of Stonely waves in the presence of viscous and gravitational effects is obtained. This is followed by particular cases of surface waves including Rayleigh waves and Love waves in the presence of viscous and gravity effects. In all cases the wave-velocity equations are found to be in perfect agreement with the corresponding classical results when the effects of gravity and viscosity are neglected.
Space weather and space anomalies
L. I. Dorman
2005-11-01
Full Text Available A large database of anomalies, registered by 220 satellites in different orbits over the period 1971-1994 has been compiled. For the first time, data from 49 Russian Kosmos satellites have been included in a statistical analysis. The database also contains a large set of daily and hourly space weather parameters. A series of statistical analyses made it possible to quantify, for different satellite orbits, space weather conditions on the days characterized by anomaly occurrences. In particular, very intense fluxes (>1000 pfu at energy >10 MeV of solar protons are linked to anomalies registered by satellites in high-altitude (>15000 km, near-polar (inclination >55° orbits typical for navigation satellites, such as those used in the GPS network, NAVSTAR, etc. (the rate of anomalies increases by a factor ~20, and to a much smaller extent to anomalies in geostationary orbits, (they increase by a factor ~4. Direct and indirect connections between anomaly occurrence and geomagnetic perturbations are also discussed.
Baker, David M. H.; Head, James W.; Phillips, Roger J.; Neumann, Gregory A.; Bierson, Carver J.; Smith, David E.; Zuber, Maria T.
2017-01-01
High-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) mission provide the opportunity to analyze the detailed gravity and crustal structure of impact features in the morphological transition from complex craters to peak-ring basins on the Moon. We calculate average radial profiles for free-air anomalies and Bouguer anomalies for peak-ring basins, proto-basins, and the largest complex craters. Complex craters and proto-basins have free-air anomalies that are positively correlated with surface topography, unlike the prominent lunar mascons (positive free-air anomalies in areas of low elevation) associated with large basins. The Bouguer gravity anomaly profiles of complex craters are highly irregular, with central positive anomalies that are generally absent or not clearly tied to interior morphology. In contrast, gravity profiles for peak-ring basins (approx. 200 km to 580 km) are much more regular and are highly correlated with surface morphology. A central positive Bouguer anomaly is confined within the peak ring and a negative Bouguer anomaly annulus extends from the edge of the positive anomaly outward to about the rim crest. A number of degraded basins lacking interior peak rings have diameters and gravity patterns similar to those of well-preserved peak-ring basins. If these structures represent degraded peak-ring basins, the number of peak-ring basins on the Moon would increase by more than a factor of two to 34. The gravity anomalies within basins are interpreted to be due to uplift of the mantle confined within the peak ring and an annulus of thickened crust between the peak ring and rim crest. We hypothesize that mantle uplift is influenced by interaction between the transient cavity and the mantle. Further, mascon formation is generally disconnected from the number of basin rings formed and occurs over a wide range of basin sizes. These observations have important implications for models of basin and mascon formation on the
Baker, David M. H.; Head, James W.; Phillips, Roger J.; Neumann, Gregory A.; Bierson, Carver J.; Smith, David E.; Zuber, Maria T.
2017-08-01
High-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) mission provide the opportunity to analyze the detailed gravity and crustal structure of impact features in the morphological transition from complex craters to peak-ring basins on the Moon. We calculate average radial profiles of free-air anomalies and Bouguer anomalies for peak-ring basins, protobasins, and the largest complex craters. Complex craters and protobasins have free-air anomalies that are positively correlated with surface topography, unlike the prominent lunar mascons (positive free-air anomalies in areas of low elevation) associated with large basins. The Bouguer gravity anomaly profiles of complex craters are highly irregular, with central positive anomalies that are generally absent or not clearly tied to interior morphology. In contrast, gravity profiles for peak-ring basins (∼200 km to 580 km) are much more regular and are highly correlated with surface morphology. A central positive Bouguer anomaly is confined within the peak ring and a negative Bouguer anomaly annulus extends from the edge of the positive anomaly outward to about the rim crest. A number of degraded basins lacking interior peak rings have diameters and gravity patterns similar to those of well-preserved peak-ring basins. If these structures represent degraded peak-ring basins, the number of peak-ring basins on the Moon would increase by more than a factor of two to 34. The gravity anomalies within basins are interpreted to be due to uplift of the mantle confined within the peak ring and an annulus of thickened crust between the peak ring and rim crest. We hypothesize that mantle uplift is influenced by interaction between the transient cavity and the mantle. Further, mascon formation is generally disconnected from the number of basin rings formed and occurs over a wide range of basin sizes. These observations have important implications for models of basin and mascon formation on the Moon
Impact Of GOCE On The Nordic Gravity Field Modelling
Yidiz, Hasan; Forsberg, René; Tscherning, C. C.
2011-01-01
GOCE level-2 Tzz and Txx gravity gradients at satellite altitude are used in combination as input data to predict surface free air gravity anomalies over the Nordic region using Least Square Collocation. We test the performance of using covariance functions created separately from Tzz gradients a...... Surface model, both the NKG-2004 quasi-geoid model of the Nordic and Baltic Area and the one obtained using second generation GOCE spherical harmonic coefficients based on time-wise method can successfully reproduce the higher level of the Baltic Sea relative to the Atlantic Ocean....
Maximum Likelihood Associative Memories
Gripon, Vincent; Rabbat, Michael
2013-01-01
Associative memories are structures that store data in such a way that it can later be retrieved given only a part of its content -- a sort-of error/erasure-resilience property. They are used in applications ranging from caches and memory management in CPUs to database engines. In this work we study associative memories built on the maximum likelihood principle. We derive minimum residual error rates when the data stored comes from a uniform binary source. Second, we determine the minimum amo...
Maximum likely scale estimation
Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo
2005-01-01
A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and....../or having different derivative orders. Although the principle is applicable to a wide variety of image models, the main focus here is on the Brownian model and its use for scale selection in natural images. Furthermore, in the examples provided, the simplifying assumption is made that the behavior...... of the measurements is completely characterized by all moments up to second order....
Specific gravity and API gravity of biodiesel and ultra-low sulfur diesel (ULSD) blends
Biodiesel is an alternative fuel made from vegetable oils and animal fats. In 2006, the U. S. Environmental Protection Agency mandated a maximum sulfur content of 15 ppm in on-road diesel fuels. Processing to produce the new ultra-low sulfur petrodiesel (ULSD) alters specific gravity (SG) and othe...
Coronary Artery Anomalies in Animals
Brian A. Scansen
2017-04-01
Full Text Available Coronary artery anomalies represent a disease spectrum from incidental to life-threatening. Anomalies of coronary artery origin and course are well-recognized in human medicine, but have received limited attention in veterinary medicine. Coronary artery anomalies are best described in the dog, hamster, and cow though reports also exist in the horse and pig. The most well-known anomaly in veterinary medicine is anomalous coronary artery origin with a prepulmonary course in dogs, which limits treatment of pulmonary valve stenosis. A categorization scheme for coronary artery anomalies in animals is suggested, dividing these anomalies into those of major or minor clinical significance. A review of coronary artery development, anatomy, and reported anomalies in domesticated species is provided and four novel canine examples of anomalous coronary artery origin are described: an English bulldog with single left coronary ostium and a retroaortic right coronary artery; an English bulldog with single right coronary ostium and transseptal left coronary artery; an English bulldog with single right coronary ostium and absent left coronary artery with a prepulmonary paraconal interventricular branch and an interarterial circumflex branch; and a mixed-breed dog with tetralogy of Fallot and anomalous origin of all coronary branches from the brachiocephalic trunk. Coronary arterial fistulae are also described including a coronary cameral fistula in a llama cria and an English bulldog with coronary artery aneurysm and anomalous shunting vessels from the right coronary artery to the pulmonary trunk. These examples are provided with the intent to raise awareness and improve understanding of such defects.
Kan, Nahomi; Maki, Takuya; Shiraishi, Kiyoshi
2016-10-01
We propose a model of gravity in which a General Relativity metric tensor and an effective metric generated from a single scalar formulated in geometric scalar gravity are mixed. We show that the model yields the exact Schwarzschild solution, along with accelerating behavior of scale factors in cosmological solutions.
No consistent bimetric gravity?
Deser, S; Waldron, A
2013-01-01
We discuss the prospects for a consistent, nonlinear, partially massless (PM), gauge symmetry of bimetric gravity (BMG). Just as for single metric massive gravity, ultimate consistency of both BMG and the putative PM BMG theory relies crucially on this gauge symmetry. We argue, however, that it does not exist.
Krasnov, Kirill
2016-01-01
Self-dual gravity is a diffeomorphism invariant theory in four dimensions that describes two propagating polarisations of the graviton and has a negative mass dimension coupling constant. Nevertheless, this theory is not only renormalisable but quantum finite, as we explain. We also collect various facts about self-dual gravity that are scattered across the literature.
Masters, Roy
2010-03-01
Flowing global gravitation initially produced space without time or mass. Space-time and mass are properties of flowing global gravitation. From its fabric, primal mass spins spontaneously giving rise to local gravitational space-time curvatures. Global gravity is the unifying background field. Gravity began flowing from its singularity with a big whoosh. It curves with angular rotational precession, creating a spatial geometry similar to the windings of a ball of string. Three-dimensional global gravity swirls locally into massive densities. Concurrently with these densities, local gravity curvatures of space-time arise. The expanse between celestial objects is not completely empty, void space as generally believed; it is antecedent gravity, a prerequisite associated field necessary for originating the first quantum particles. Gravity is dark energy; gravity's spin, as the second fundamental force, is electromagnetic dark matter. Electromagnetic masses attract then gravity compresses hot, dense and small---then bang, the first hydrogen star of which there are many. There may have been many big bangs, but no Big Bang that ultimately created the universe.
Pre-impact crustal porosity and its effect on the gravity signature of lunar craters
Milbury, Colleen; Johnson, Brandon C.; Melosh, H. Jay; Collins, Gareth C.; Blair, David M.; Soderblom, Jason M.; Zuber, Maria T.
2015-04-01
NASA's dual Gravity Recovery and Interior Laboratory (GRAIL) spacecraft have globally mapped the lunar gravity field at unprecedented resolution. Soderblom et al. [2015] made a comprehensive analysis of the residual and central uplift Bouguer gravity anomalies associated with more than 5200 lunar craters. There were two main observations that are related to the work presented here: 1) craters less than ~150 km in diameter (D) have a residual Bouguer anomaly (BA) that is near zero on average (although a negative trend is observed), but have both positive and negative anomalies that vary by approximately ±25 mGal about the mean, and, 2) there is a transition at which the central uplift BA becomes positive and increases with D. Craters that are located in the maria and South Pole-Aitken (SPA) basin were excluded from the analysis because they tend to have more negative signatures than highlands craters. These gravitational signatures contrast with the invariably negative gravity anomalies associated with terrestrial craters. In this study, we investigate pre-impact porosity by modeling crater formation using the iSALE hydrocode, including a new approach to include dilatancy, to determine their effects on the gravity signature of craters. We calculated the BA for the simulations, but due to mantle uplift alone. We find that the magnitude of the BA increases with increasing porosity, and that variable initial porosity of the lunar crust can explain why craters on the Moon exhibit both positive and negative Bouguer anomalies. This can also explain the observed negative residual BA associated with craters formed in the lunar maria and SPA (and associated melt sheet) because they are typically less porous than the highlands crust. Gravity anomalies due to mantle uplift reproduce the observed transition from zero to a positive central uplift BA, which coincides with the morphological transition from complex craters to peak-ring basins.
3-Space In-Flow Theory of Gravity: Boreholes, Blackholes and the Fine Structure Constant
Cahill R. T.
2006-04-01
Full Text Available A theory of 3-space explains the phenomenon of gravity as arising from the time-dependence and inhomogeneity of the differential flow of this 3-space. The emergent theory of gravity has two gravitational constants: G - Newton's constant, and a dimensionless constant alpha. Various experiments and astronomical observations have shown that alpha is the fine structure constant ~1/137. Here we analyse the Greenland Ice Shelf and Nevada Test Site borehole g anomalies, and confirm with increased precision this value of alpha. This and other successful tests of this theory of gravity, including the supermassive black holes in globular clusters and galaxies, and the "dark-matter" effect in spiral galaxies, shows the validity of this theory of gravity. This success implies that the non-relativistic Newtonian gravity was fundamentally flawed from the beginning, and that this flaw was inherited by the relativistic General Relativity theory of gravity.
3-Space In-Flow Theory of Gravity: Boreholes, Blackholes and the Fine Structure Constant
Cahill R. T.
2006-04-01
Full Text Available A theory of 3-space explains the phenomenon of gravity as arising from the time-dependence and inhomogeneity of the differential flow of this 3-space. The emergent theory of gravity has two gravitational constants: GN — Newton’s constant, and a dimensionless constant α. Various experiments and astronomical observations have shown that α is the fine structure constant ≈ 1/137. Here we analyse the Greenland Ice Shelf and Nevada Test Site borehole g anomalies, and confirm with increased precision this value of α. This and other successful tests of this theory of gravity, including the supermassive black holes in globular clusters and galaxies, and the “dark-matter” effect in spiral galaxies, shows the validity of this theory of gravity. This success implies that the non-relativistic Newtonian gravity was fundamentally flawed from the beginning, and that this flaw was inherited by the relativistic General Relativity theory of gravity.
Arctic Ocean gravity, geoid and sea-ice freeboard heights from ICESat and GRACE
Forsberg, René; Skourup, Henriette
2005-01-01
ICESat laser measurements provide a high-resolution mapping of the sea-ice surface of the Arctic Ocean, which can be inverted to determine gravity anomalies and sea-ice freeboard heights by a "lowest-level'' filtering scheme. In this paper we use updated terrestrial gravity data from the Arctic...... all major tectonic features of the Arctic Ocean, and has an accuracy of 6 mGal compared to recent airborne gravity data, illustrating the usefulness of ICESat data for gravity field determination....... Gravity Project in combination with GRACE gravity field models to derive an improved Arctic geoid model. This model is then used to convert ICESat measurements to sea-ice freeboard heights with a coarse lowest-level surface method. The derived freeboard heights show a good qualitative agreement...
Aeromagrnetic study of the midcontinent gravity high of central United States
King, Elizabeth R.; Zietz, Isidore
1971-01-01
A composite map of detailed aeromagnetic surveys over the midcontinent gravity high provides coverage of the 600-mi-long buried belt of mafic rocks of the Keweenawan Series from their outcrop localities in Minnesota and Wisconsin through Iowa and Nebraska. A map of the subsurface extent of the mafic rocks, based on the intricate magnetic patterns, shows that the rocks form a long, semicontinuous block, averaging 40 mi wide and consisting mainly of a sequence of layered flows. This sequence is probably fault-bounded and has been tilted up along the margins, where the linearity of the anomalies indicates steeper dips. The associated clastic rocks, indicated by a smoother magnetic pattern, occur in basins along both sides of the mafic belt and in grabens and a series of axial basins on the upper surface of the block. The well-defined outliers of flows marginal to the main block and the truncation of some of the outermost flow units along a diagonal boundary striking at an angle to them suggest that the present boundaries of the block are postdepositional structural features. The basins and the edges of the block appear to have controlled later, largely vertical movement in the overlying Paleozoic and younger sedimentary cover. Calculated models based on coincident magnetic and detailed gravity profiles along typical cross sections of the midcontinent gravity high show that the block of mafic rocks is steep-sided and as much as several miles thick. The free-air gravity anomaly, which consists of a large positive maximum flanked by minima, averages very close to zero, indicating that this major crustal feature is regionally compensated, although locally each of its components shows a large departure from equilibrium. Remanent magnetization is a primary factor in the interpretation of the magnetic data. Magnetic property studies of Keweenawan mafic rocks in the Lake Superior region show that remanent magnetization may be five times the magnetization induced by the
Aeromagnetic study of the midcontinent gravity high of central United States
King, Elizabeth R.; Zietz, Isidore
1971-01-01
A composite map of detailed aeromagnetic surveys over the midcontinent gravity high provides coverage of the 600-mi-long buried belt of mafic rocks of the Keweenawan Series from their outcrop localities in Minnesota and Wisconsin through Iowa and Nebraska. A map of the subsurface extent of the mafic rocks, based on the intricate magnetic patterns, shows that the rocks form a long, semicontinuous block, averaging 40 mi wide and consisting mainly of a sequence of layered flows. This sequence is probably fault-bounded and has been tilted up along the margins, where the linearity of the anomalies indicates steeper dips. The associated clastic rocks, indicated by a smoother magnetic pattern, occur in basins along both sides of the mafic belt and in grabens and a series of axial basins on the upper surface of the block. The well-defined outliers of flows marginal to the main block and the truncation of some of the outermost flow units along a diagonal boundary striking at an angle to them suggest that the present boundaries of the block are postdepositional structural features. The basins and the edges of the block appear to have controlled later, largely vertical movement in the overlying Paleozoic and younger sedimentary cover. Calculated models based on coincident magnetic and detailed gravity profiles along typical cross sections of the midcontinent gravity high show that the block of mafic rocks is steep-sided and as much as several miles thick. The free-air gravity anomaly, which consists of a large positive maximum flanked by minima, averages very close to zero, indicating that this major crustal feature is regionally compensated, although locally each of its components shows a large departure from equilibrium. Remanent magnetization is a primary factor in the interpretation of the magnetic data. Magnetic property studies of Keweenawan mafic rocks in the Lake Superior region show that remanent magnetization may be five times the magnetization induced by the
F. TopsÃƒÂ¸e
2001-09-01
Full Text Available Abstract: In its modern formulation, the Maximum Entropy Principle was promoted by E.T. Jaynes, starting in the mid-fifties. The principle dictates that one should look for a distribution, consistent with available information, which maximizes the entropy. However, this principle focuses only on distributions and it appears advantageous to bring information theoretical thinking more prominently into play by also focusing on the "observer" and on coding. This view was brought forward by the second named author in the late seventies and is the view we will follow-up on here. It leads to the consideration of a certain game, the Code Length Game and, via standard game theoretical thinking, to a principle of Game Theoretical Equilibrium. This principle is more basic than the Maximum Entropy Principle in the sense that the search for one type of optimal strategies in the Code Length Game translates directly into the search for distributions with maximum entropy. In the present paper we offer a self-contained and comprehensive treatment of fundamentals of both principles mentioned, based on a study of the Code Length Game. Though new concepts and results are presented, the reading should be instructional and accessible to a rather wide audience, at least if certain mathematical details are left aside at a rst reading. The most frequently studied instance of entropy maximization pertains to the Mean Energy Model which involves a moment constraint related to a given function, here taken to represent "energy". This type of application is very well known from the literature with hundreds of applications pertaining to several different elds and will also here serve as important illustration of the theory. But our approach reaches further, especially regarding the study of continuity properties of the entropy function, and this leads to new results which allow a discussion of models with so-called entropy loss. These results have tempted us to speculate over
Gravity, magnetic, and radiometric data for Newberry Volcano, Oregon, and vicinity
Wynn, Jeff
2014-01-01
Newberry Volcano in central Oregon is a 3,100-square-kilometer (1,200-square-mile) shield-shaped composite volcano, occupying a location east of the main north-south trend of the High Cascades volcanoes and forming a transition between the High Lava Plains subprovince of the Basin and Range Province to the east and the Cascade Range to the west. Magnetic, gravity, and radiometric data have been gathered and assessed for the region around the volcano. These data have widely varying quality and resolution, even within a given dataset, and these limitations are evaluated and described in this release. Publicly available gravity data in general are too sparse to permit detailed modeling except along a few roads with high-density coverage. Likewise, magnetic data are also unsuitable for all but very local modeling, primarily because available data consist of a patchwork of datasets with widely varying line-spacing. Gravity data show only the broadest correlation with mapped geology, whereas magnetic data show moderate correlation with features only in the vicinity of Newberry Caldera. At large scales, magnetic data correlate poorly with both geologic mapping and gravity data. These poor correlations are largely due to the different sensing depths of the two potential fields methods, which respond to physical properties deeper than the surficial geology. Magnetic data derive from rocks no deeper than the Curie-point isotherm depth (10 to 15 kilometers, km, maximum), whereas gravity data reflect density-contrasts to 100 to 150 km depths. Radiometric data from the National Uranium Resource Evaluation (NURE) surveys of the 1980s have perhaps the coarsest line-spacing of all (as much as 10 km between lines) and are extremely “noisy” for several reasons inherent to this kind of data. Despite its shallow-sensing character, only a few larger anomalies in the NURE data correlate well with geologic mapping. The purpose of this data series release is to collect and place the
Extraction method of suitable matching regions in the gravity-aided inertial navigation
Yan, Li; Ma, Xudong; Shi, Juan; Shi, Yulong
2009-10-01
The data organization of gravitational field is based on a form of Grid, which is similar to the data structure of DEM in the terrain. So this paper proposes a method of gravitational field analysis for extracting features by adopting some spatial analysis means of topography. First of all, the gravity anomaly data is used to calculate the roughness features of gravitational field. after comparing and anglicizing the features, roughness features are selected as the feature factor of gravity. Then, the method of calculating contour lines is applied to calculate region segmentation of roughness features and extract the vector edge of the larger feature regions, and clustering analysis to these contour of the region. At last, the scope line for Convex Hull of the region is calculated by the Convex Hull algorithm, and so as to obtain a more prominent region (matching region) that have significant changes in gravity anomaly, which provide the necessary reference data for the gravity-aided inertial navigation.
Regularized maximum correntropy machine
Wang, Jim Jing-Yan
2015-02-12
In this paper we investigate the usage of regularized correntropy framework for learning of classifiers from noisy labels. The class label predictors learned by minimizing transitional loss functions are sensitive to the noisy and outlying labels of training samples, because the transitional loss functions are equally applied to all the samples. To solve this problem, we propose to learn the class label predictors by maximizing the correntropy between the predicted labels and the true labels of the training samples, under the regularized Maximum Correntropy Criteria (MCC) framework. Moreover, we regularize the predictor parameter to control the complexity of the predictor. The learning problem is formulated by an objective function considering the parameter regularization and MCC simultaneously. By optimizing the objective function alternately, we develop a novel predictor learning algorithm. The experiments on two challenging pattern classification tasks show that it significantly outperforms the machines with transitional loss functions.
An Extreme-Value Approach to Anomaly Vulnerability Identification
Everett, Chris; Maggio, Gaspare; Groen, Frank
2010-01-01
The objective of this paper is to present a method for importance analysis in parametric probabilistic modeling where the result of interest is the identification of potential engineering vulnerabilities associated with postulated anomalies in system behavior. In the context of Accident Precursor Analysis (APA), under which this method has been developed, these vulnerabilities, designated as anomaly vulnerabilities, are conditions that produce high risk in the presence of anomalous system behavior. The method defines a parameter-specific Parameter Vulnerability Importance measure (PVI), which identifies anomaly risk-model parameter values that indicate the potential presence of anomaly vulnerabilities, and allows them to be prioritized for further investigation. This entails analyzing each uncertain risk-model parameter over its credible range of values to determine where it produces the maximum risk. A parameter that produces high system risk for a particular range of values suggests that the system is vulnerable to the modeled anomalous conditions, if indeed the true parameter value lies in that range. Thus, PVI analysis provides a means of identifying and prioritizing anomaly-related engineering issues that at the very least warrant improved understanding to reduce uncertainty, such that true vulnerabilities may be identified and proper corrective actions taken.
Hydrothermal plume anomalies along the Central Indian Ridge
ZHU Jian; LIN Jian; GUO ShiQin; CHEN YongShun
2008-01-01
Water column turbidity and temperature were investigated along the Central Indian Ridge (CIR) from 25°19'S to 23°48'S during a December 2005 cruise on board Chinese P/V DayangYihao.Measurements were made using NOAA's MAPR (Miniature Autonomous Plume Recorder) sensors during CTD casts,TV grabber operations,and tow-yo profiles,yielding the following results on hydrothermal plume anomalies:(1) Strong hydrothermal turbidity and temperature anomalies were recorded over the pre-viously discovered Kairei (25°19.2'S,70°02.4'E) and Edmond (23°52.7'S,69°35.8"E) vent fields,with the plume anomalies concentrated at depths of 2150-2300 m and 2700-2900 m,respectively.The maxi-mum height of the turbidity anomalies near the Kairei vent field recorded in December 2005 was slightly below 2100 m,which is consistent with the plume depth measured in June 2001,indicating that the Kairei plume may have maintained its buoyancy flux in the intervening 4.5 years.(2) The water column beneath the Kairei plume has background anomalies of about 0.005△NTU,whereas no such back-ground turbidity anomalies were observed below the Edmond hydrothermal plume.(3) No visible tur-bidity anomalies were detected from 24°42'S to 24°12'S including the Knorr Seamount.Thus 24°12'S marks the southern end of the hydrothermal plume.(4) Significant turbidity anomalies were observed at four individual sections from 24°12'S to 23°56'S at the depth of 2500-3000 m along the eastern rift valley wall.Whether the individual sections of anomalies are connected is still unknown due to the absence of data at the intervening gaps.If the four sections are connected with each other and are linked to the Edmond vent field farther to the north,the total along-axis length of the plume anomaly would be more than 37 km,implying a plume incidence value Ph of 0.38,greater than the predicted Ph of 0.21-0.25 based on the spreading rate of the Central Indian Ridge.
Mapping the mass distribution of Earth's mantle using satellite-derived gravity gradients
Panet, Isabelle; Pajot-Métivier, Gwendoline; Greff-Lefftz, Marianne; Métivier, Laurent; Diament, Michel; Mandea, Mioara
2014-02-01
The dynamics of Earth's mantle are not well known. Deciphering mantle flow patterns requires an understanding of the global distribution of mantle density. Seismic tomography has been used to derive mantle density distributions, but converting seismic velocities into densities is not straightforward. Here we show that data from the GOCE (Gravity field and steady-state Ocean Circulation Explorer) mission can be used to probe our planet's deep mass structure. We construct global anomaly maps of the Earth's gravitational gradients at satellite altitude and use a sensitivity analysis to show that these gravitational gradients image the geometry of mantle mass down to mid-mantle depths. Our maps highlight north-south-elongated gravity gradient anomalies over Asia and America that follow a belt of ancient subduction boundaries, as well as gravity gradient anomalies over the central Pacific Ocean and south of Africa that coincide with the locations of deep mantle plumes. We interpret these anomalies as sinking tectonic plates and convective instabilities between 1,000 and 2,500km depth, consistent with seismic tomography results. Along the former Tethyan Margin, our data also identify an east-west-oriented mass anomaly likely in the upper mantle. We suggest that by combining gravity gradients with seismic and geodynamic data, an integrated dynamic model for Earth can be achieved.
The Flyby Anomaly in an Extended Whitehead’s Theory
Luis Acedo
2015-07-01
Full Text Available In this paper, we consider an extended version of Whitehead’s theory of gravity in connection with the flyby anomaly. Whitehead’s theory is a linear approximation defined in a background Minkowski spacetime, which gives the same solutions as standard general relativity for the Schwarzschild and Kerr metrics cast in Kerr–Schild coordinates. For a long time and because it gives the same results for the three classical tests—perihelion advance, light bending and gravitational redshift—it was considered a viable alternative to general relativity, but as it is really a linear approximation, it fails in more stringent tests. The model considered in this paper is a formal generalization of Whitehead’s theory, including all possible bilinear forms. In the resulting theory, a circulating vector field of force in the low velocities’ approximation for a rotating planet is deduced, in addition to Newtonian gravity. This extra force gives rise to small variations in the asymptotic velocities of flybys around the Earth to be compared to the recently reported flyby anomaly.
Shortening Anomalies in Supersymmetric Theories
Gomis, Jaume; Ooguri, Hirosi; Seiberg, Nathan; Wang, Yifan
2016-01-01
We present new anomalies in two-dimensional ${\\mathcal N} =(2, 2)$ superconformal theories. They obstruct the shortening conditions of chiral and twisted chiral multiplets at coincident points. This implies that marginal couplings cannot be promoted to background super-fields in short representations. Therefore, standard results that follow from ${\\mathcal N} =(2, 2)$ spurion analysis are invalidated. These anomalies appear only if supersymmetry is enhanced beyond ${\\mathcal N} =(2, 2)$. These anomalies explain why the conformal manifolds of the K3 and $T^4$ sigma models are not K\\"ahler and do not factorize into chiral and twisted chiral moduli spaces and why there are no ${\\mathcal N} =(2, 2)$ gauged linear sigma models that cover these conformal manifolds. We also present these results from the point of view of the Riemann curvature of conformal manifolds.
Boundary terms of conformal anomaly
Sergey N. Solodukhin
2016-01-01
Full Text Available We analyze the structure of the boundary terms in the conformal anomaly integrated over a manifold with boundaries. We suggest that the anomalies of type B, polynomial in the Weyl tensor, are accompanied with the respective boundary terms of the Gibbons–Hawking type. Their form is dictated by the requirement that they produce a variation which compensates the normal derivatives of the metric variation on the boundary in order to have a well-defined variational procedure. This suggestion agrees with recent findings in four dimensions for free fields of various spins. We generalize this consideration to six dimensions and derive explicitly the respective boundary terms. We point out that the integrated conformal anomaly in odd dimensions is non-vanishing due to the boundary terms. These terms are specified in three and five dimensions.
Multiple Visceral and Peritoneal Anomalies
Gayathri Prabhu S
2016-07-01
Full Text Available Visceral and peritoneal anomalies are frequently encountered during cadaveric dissections and surgical procedures of abdomen. A thorough knowledge of the same is required for the success of diagnostic, surgical and radiological procedures of abdomen. We report multiple peritoneal and visceral anomalies noted during dissection classes for medical undergraduates. The anomalies were found in an adult male cadaver aged approximately 70 years. The right iliac fossa was empty due to the sub-hepatic position of caecum and appendix. The sigmoid colon formed an inverted “U” shaped loop above the sacral promontory in the median position. It entered the pelvis from the right side and descended along the lateral wall of the pelvis. The sigmoid mesocolon was attached obliquely to the posterior abdominal wall, just above the sacral promontory. Further there was a cysto-colic fold of peritoneum extending from the right colic flexure. We discuss the clinical significance of the variations.
Electromagnetic Duality and Entanglement Anomalies
Donnelly, William; Wall, Aron
2016-01-01
Duality is an indispensable tool for describing the strong-coupling dynamics of gauge theories. However, its actual realization is often quite subtle: quantities such as the partition function can transform covariantly, with degrees of freedom rearranged in a nonlocal fashion. We study this phenomenon in the context of the electromagnetic duality of abelian $p$-forms. A careful calculation of the duality anomaly on an arbitrary $D$-dimensional manifold shows that the effective actions agree exactly in odd $D$, while in even $D$ they differ by a term proportional to the Euler number. Despite this anomaly, the trace of the stress tensor agrees between the dual theories. We also compute the change in the vacuum entanglement entropy under duality, relating this entanglement anomaly to the duality of an "edge mode" theory in two fewer dimensions. Previous work on this subject has led to conflicting results; we explain and resolve these discrepancies.
Conformal Anomalies and Gravitational Waves
Meissner, Krzysztof A
2016-01-01
We argue that the presence of conformal anomalies in gravitational theories can lead to observable modifications to Einstein's equations via the induced anomalous effective actions, whose non-localities can overwhelm the smallness of the Planck scale. The fact that no such effects have been seen in recent cosmological or gravitational wave observations therefore imposes strong restrictions on the field content of possible extensions of Einstein's theory: all viable theories should have vanishing conformal anomalies. We then show that, among presently known theories, a complete cancellation of conformal anomalies in $D=4$ for both the $C^2$ invariant and the Euler (Gauss-Bonnet) invariant $E_4$ can only be achieved for $N$-extended supergravities with $N\\geq 5$, as well as for M theory compactified to four dimensions.
Boundary terms of conformal anomaly
Solodukhin, Sergey N., E-mail: Sergey.Solodukhin@lmpt.univ-tours.fr
2016-01-10
We analyze the structure of the boundary terms in the conformal anomaly integrated over a manifold with boundaries. We suggest that the anomalies of type B, polynomial in the Weyl tensor, are accompanied with the respective boundary terms of the Gibbons–Hawking type. Their form is dictated by the requirement that they produce a variation which compensates the normal derivatives of the metric variation on the boundary in order to have a well-defined variational procedure. This suggestion agrees with recent findings in four dimensions for free fields of various spins. We generalize this consideration to six dimensions and derive explicitly the respective boundary terms. We point out that the integrated conformal anomaly in odd dimensions is non-vanishing due to the boundary terms. These terms are specified in three and five dimensions.
Covariance in models of loop quantum gravity: Gowdy systems
Bojowald, Martin
2015-01-01
Recent results in the construction of anomaly-free models of loop quantum gravity have shown obstacles when local physical degrees of freedom are present. Here, a set of no-go properties is derived in polarized Gowdy models, raising the question whether these systems can be covariant beyond a background treatment. As a side product, it is shown that normal deformations in classical polarized Gowdy models can be Abelianized.
Parsons, T.; Blakely, R.J.; Brocher, T.M.
2001-01-01
The geologic structure of the Earth's upper crust can be revealed by modeling variation in seismic arrival times and in potential field measurements. We demonstrate a simple method for sequentially satisfying seismic traveltime and observed gravity residuals in an iterative 3-D inversion. The algorithm is portable to any seismic analysis method that uses a gridded representation of velocity structure. Our technique calculates the gravity anomaly resulting from a velocity model by converting to density with Gardner's rule. The residual between calculated and observed gravity is minimized by weighted adjustments to the model velocity-depth gradient where the gradient is steepest and where seismic coverage is least. The adjustments are scaled by the sign and magnitude of the gravity residuals, and a smoothing step is performed to minimize vertical streaking. The adjusted model is then used as a starting model in the next seismic traveltime iteration. The process is repeated until one velocity model can simultaneously satisfy both the gravity anomaly and seismic traveltime observations within acceptable misfits. We test our algorithm with data gathered in the Puget Lowland of Washington state, USA (Seismic Hazards Investigation in Puget Sound [SHIPS] experiment). We perform resolution tests with synthetic traveltime and gravity observations calculated with a checkerboard velocity model using the SHIPS experiment geometry, and show that the addition of gravity significantly enhances resolution. We calculate a new velocity model for the region using SHIPS traveltimes and observed gravity, and show examples where correlation between surface geology and modeled subsurface velocity structure is enhanced.
Boundary Anomalies and Correlation Functions
Huang, Kuo-Wei
2016-01-01
It was shown recently that boundary terms of conformal anomalies recover the universal contribution to the entanglement entropy and also play an important role in the boundary monotonicity theorem of odd-dimensional quantum field theories. Motivated by these results, we investigate relationships between boundary anomalies and the stress tensor correlation functions in conformal field theories. In particular, we focus on how the conformal Ward identity and the renormalization group equation are modified by boundary central charges. Renormalized stress tensors induced by boundary Weyl invariants are also discussed, with examples in spherical and cylindrical geometries.
Analysis of pre-earthquake ionospheric anomalies before the global M = 7.0+ earthquakes in 2010
W. F. Peng
2012-03-01
Full Text Available The pre-earthquake ionospheric anomalies that occurred before the global M = 7.0+ earthquakes in 2010 are investigated using the total electron content (TEC from the global ionosphere map (GIM. We analyze the possible causes of the ionospheric anomalies based on the space environment and magnetic field status. Results show that some anomalies are related to the earthquakes. By analyzing the time of occurrence, duration, and spatial distribution of these ionospheric anomalies, a number of new conclusions are drawn, as follows: earthquake-related ionospheric anomalies are not bound to appear; both positive and negative anomalies are likely to occur; and the earthquake-related ionospheric anomalies discussed in the current study occurred 0–2 days before the associated earthquakes and in the afternoon to sunset (i.e. between 12:00 and 20:00 local time. Pre-earthquake ionospheric anomalies occur mainly in areas near the epicenter. However, the maximum affected area in the ionosphere does not coincide with the vertical projection of the epicenter of the subsequent earthquake. The directions deviating from the epicenters do not follow a fixed rule. The corresponding ionospheric effects can also be observed in the magnetically conjugated region. However, the probability of the anomalies appearance and extent of the anomalies in the magnetically conjugated region are smaller than the anomalies near the epicenter. Deep-focus earthquakes may also exhibit very significant pre-earthquake ionospheric anomalies.
The Kenya rift axial gravity high: a re-interpretation
Swain, C. J.
1992-03-01
Since KRISP 85 did not provide overwhelming evidence for the massive intrusion that was originally suggested to explain the axial gravity high yet did provide a velocity section for the upper crust along the axis of the Kenya Rift, it is appropriate to use this section to control a re-interpretation of the gravity anomalies. A 2 {1}/{2} D inversion procedure has been used to model a number of isostatic anomaly profiles between Lake Baringo and Suswa. There are too many unknowns and gravity station coverage is too sparse for the results to be unique. Nevertheless, certain conclusions can be drawn. One of those is that some relatively dense material exists within the basement all along the Rift axis, since the axial isostatic anomalies are positive even though they occur where there are several thousand metres of Cenozoic volcanics of relatively low density (inferred from their seismic velocity of 3.7-5.1 km/s). The dense material is envisaged as a zone of dyke injection and assigned a density of 2.75-2.76 g/cm 3 (corresponding to its 6.05 km/s velocity) compared to a normal basement density of 2.70 g/cm 3. It is assumed to extend down to 22 km—the top of the 7.1 km/s layer. The KRISP 85 line passed just east of Menengai, where the basement velocity increases to about 6.6 km/s over a distance of about 20 km. On an east-west gravity profile through Menengai there is a gravity high corresponding to this velocity increase which has been modelled as a basic intrusion (density 2.93 g/cm 3) underlying the caldera.
Equalized near maximum likelihood detector
2012-01-01
This paper presents new detector that is used to mitigate intersymbol interference introduced by bandlimited channels. This detector is named equalized near maximum likelihood detector which combines nonlinear equalizer and near maximum likelihood detector. Simulation results show that the performance of equalized near maximum likelihood detector is better than the performance of nonlinear equalizer but worse than near maximum likelihood detector.
Cheeseman, Peter; Stutz, John
2005-01-01
A long standing mystery in using Maximum Entropy (MaxEnt) is how to deal with constraints whose values are uncertain. This situation arises when constraint values are estimated from data, because of finite sample sizes. One approach to this problem, advocated by E.T. Jaynes [1], is to ignore this uncertainty, and treat the empirically observed values as exact. We refer to this as the classic MaxEnt approach. Classic MaxEnt gives point probabilities (subject to the given constraints), rather than probability densities. We develop an alternative approach that assumes that the uncertain constraint values are represented by a probability density {e.g: a Gaussian), and this uncertainty yields a MaxEnt posterior probability density. That is, the classic MaxEnt point probabilities are regarded as a multidimensional function of the given constraint values, and uncertainty on these values is transmitted through the MaxEnt function to give uncertainty over the MaXEnt probabilities. We illustrate this approach by explicitly calculating the generalized MaxEnt density for a simple but common case, then show how this can be extended numerically to the general case. This paper expands the generalized MaxEnt concept introduced in a previous paper [3].
Phenomenological Quantum Gravity
Hossenfelder, Sabine
2009-01-01
If the history of science has taught us anything, it's that persistence and creativity makes the once impossible possible. It has long been thought experimental tests of quantum gravity are impossible. But during the last decade, several different approaches have been proposed that allow us to test, if not the fundamental theory of quantum gravity itself, so at least characteristic features this theory can have. For the first time we can probe experimentally domains in which quantum physics and gravity cohabit, in spite of our failure so far to make a convincing marriage of them on a theoretical level.
The Crustal Thickness of the Philippine Sea Plate Derived from Gravity Data
Horng-Yuan Yen
2015-01-01
Full Text Available We constructed a new free-air gravity anomaly map of the Philippine Sea Plate (PSP using ship-tracked gravity data from the National Geophysical Data Center (NGDC. Our results show that the isogals trend correlates well with the tectonic structures in the PSP. After removing the gravity induced by sea water from the free-air gravity data, we obtained the regional Bouguer gravity anomaly, which is later used to compute the Moho geometry in the PSP by applying the Parker-Oldenburg iterative method. Our results indicate that in the southern part of the West Philippine Basin (WPB the crustal thickness is nearly homogeneous with a value of about 5 km, which implies that the WPB is quite stable. The low-amplitude and near-zero free-air gravity anomalies clearly indicate that the whole WPB, except at trenches and island arcs, is nearly in a state of isostatic equilibrium. The average crustal thickness of the Palau Kyushu Ridge (PKR is more than 10 km. In the eastern PSP the crustal thickness gradually increases eastward. Our results also imply that a relatively thin and low density mantle exists beneath the Parece Vela Basin (PVB as a consequence of back-arc spreading and serpentinized upwells of the thin crustal thickness.
Cosmology with Coupled Gravity and Dark Energy
Li, Ti-Pei
2014-01-01
The dark energy is a fundamental constitution of our universe, its role in the cosmological field equation should just like the gravity. Here we construct a dark energy and gravity coupling (DEMC) model of cosmology in a way that gravity and dark energy are introduced into the cosmological field equation in parallel to each other from the beginning. The DEMC universe possesses a composite symmetry constituted from the global Galileo invariance and local Lorentz invariance. The observed evolution trend of expansion rate at redshift z>1 is in tension with the standard LCDM model, but can be well predicted from measurements for only near epoch by the DEMC model. The so far most precise measured expansion rate at high z is quite a bit slower than the expectation from LCDM, but remarkably consistent with that from DEMC. It is hopeful that the DEMC scenario can also help to solve existed challenges to cosmology: large scale anomalies in CMB maps and large structures with dimension up to about 10^3 Mpc of a quasar g...
Davis, D.A.; Cook, K.L.
1983-04-01
During 1980 and 1981 a total of 569 new gravity stations were taken in Utah and Goshen Valleys and adjacent areas, Utah. The new stations were combined with 530 other gravity stations taken in previous surveys which resulted in a compilation of 1099 stations which were used in this study. The additional surveys were undertaken to assist in the evaluation of the area for the possible development of geothermal resources by providing an interpreted structural framework by delineating faults, structural trends, intrusions, thickness of valley fill, and increased density of host rock. The gravity data are presented as (1) a complete Bouguer gravity anomaly map with a 2 mgal contour interval on a scale of 1:100,000 and (2) five generally east-trending gravity profiles. A geologic interpretation of the study area was made from the gravity map and from the interpretive geologic cross sections which were modeled along the gravity profiles.
Gravity study of the Pitcairn-Easter hotline
Maia, M.; Dehghani, G. A.; Diament, M.; Francheteau, J.; Stoffers, P.
1994-11-01
Shipboard free air gravity and bathymetric anomalies with an extension of 400 km were identified across the Pitcairn-Easter hotline in the South Pacific. The anomalies are associated with one of the positive geoid undulations observed in the area from satellite data. Several smaller topographic features, volcano-tectonic ridges oriented N 65 deg E, are superimposed on the topographic hig. Admittance computations and direct modeling show that the swell topography is compensated by a low density zone within the lithosphere, 4 to 8 km below the crust. The volcano tectonic ridges are locally compensated in a classical Airy sense. The swell and the associated ridges were probably created by the action of a thermal anomaly resulting from the interaction of the Easter Island hotspot and of the Easter Microplate accretion centers.
Constraining gravity with hadron physics: neutron stars, modified gravity and gravitational waves
Llanes-Estrada, Felipe J
2016-01-01
The finding of Gravitational Waves by the aLIGO scientific and VIRGO collaborations opens opportunities to better test and understand strong interactions, both nuclear-hadronic and gravitational. Assuming General Relativity holds, one can constrain hadron physics at a neutron star. But precise knowledge of the Equation of State and transport properties in hadron matter can also be used to constrain the theory of gravity itself. I review a couple of these opportunities in the context of modified f(R) gravity, the maximum mass of neutron stars, and progress in the Equation of State of neutron matter from the chiral effective field theory of QCD.
Constraining gravity with hadron physics: neutron stars, modified gravity and gravitational waves
Llanes-Estrada, Felipe J.
2017-03-01
The finding of Gravitational Waves (GW) by the aLIGO scientific and VIRGO collaborations opens opportunities to better test and understand strong interactions, both nuclear-hadronic and gravitational. Assuming General Relativity holds, one can constrain hadron physics at a neutron star. But precise knowledge of the Equation of State and transport properties in hadron matter can also be used to constrain the theory of gravity itself. I review a couple of these opportunities in the context of modified f (R) gravity, the maximum mass of neutron stars, and progress in the Equation of State of neutron matter from the chiral effective field theory of QCD.
Global gravitational anomalies and transport
Chowdhury, Subham Dutta; David, Justin R.
2016-12-01
We investigate the constraints imposed by global gravitational anomalies on parity odd induced transport coefficients in even dimensions for theories with chiral fermions, gravitinos and self dual tensors. The η-invariant for the large diffeomorphism corresponding to the T transformation on a torus constraints the coefficients in the thermal effective action up to mod 2. We show that the result obtained for the parity odd transport for gravitinos using global anomaly matching is consistent with the direct perturbative calculation. In d = 6 we see that the second Pontryagin class in the anomaly polynomial does not contribute to the η-invariant which provides a topological explanation of this observation in the `replacement rule'. We then perform a direct perturbative calculation for the contribution of the self dual tensor in d = 6 to the parity odd transport coefficient using the Feynman rules proposed by Gaumé and Witten. The result for the transport coefficient agrees with that obtained using matching of global anomalies.
Anomalies and noncommutative index theory
Perrot, D
2006-01-01
These are the notes of a lecture given during the summer school "Geometric and Topological Methods for Quantum Field Theory", Villa de Leyva, Colombia, july 11 - 29, 2005. We review basic facts concerning gauge anomalies and discuss the link with the Connes-Moscovici index formula in noncommutative geometry.
Bony anomaly of Meckel's cave.
Tubbs, R Shane; Salter, E George; Oakes, W Jerry
2006-01-01
This study describes the seemingly rare occurrence of bone formation within the proximal superior aspect of Meckel's cave thus forming a bony foramen for the proximal trigeminal nerve to traverse. The anatomy of Meckel's cave is reviewed and the clinical potential for nerve compression from this bony anomaly discussed.
Conformal anomalies and gravitational waves
Meissner, Krzysztof A.; Nicolai, Hermann
2017-09-01
We argue that the presence of conformal anomalies in gravitational theories can lead to observable modifications to Einstein's equations via the induced anomalous effective actions, whose non-localities can overwhelm the smallness of the Planck scale. The fact that no such effects have been seen in recent cosmological or gravitational wave observations therefore imposes strong restrictions on the field content of possible extensions of Einstein's theory: all viable theories should have vanishing conformal anomalies. We then show that a complete cancellation of conformal anomalies in D = 4 for both the C2 invariant and the Euler (Gauss-Bonnet) invariant E4 can only be achieved for N-extended supergravity multiplets with N ⩾ 5, as well as for M theory compactified to four dimensions. Although there remain open questions, in particular concerning the true significance of conformal anomalies in non-conformal theories, as well as their possible gauge dependence for spin s ⩾3/2, these cancellations suggest a hidden conformal structure of unknown type in these theories.
Connecting Stratospheric and Ionospheric Anomalies
Spraggs, M. E.; Goncharenko, L. P.; Zhang, S.; Coster, A. J.; Benkevitch, L. V.
2014-12-01
This study investigates any relationship between lunar phases and ionospheric anomalies that appear at low latitudes concurrently with sudden stratospheric warmings (SSWs). The study utilizes World-wide GPS Receiver Network Total Electron Content (TEC) data spanning 13 years (2001-2014) and focuses on the changes in the equatorial ionization anomaly the Western hemisphere. TEC is highly variable due to the influences of solar flux, geomagnetic activity, and seasonal variation and these influences are removed by the use of model. This empirical TEC model is a combination of linear dependencies of solar flux (F10.7) and geomagnetic activity (Ap3) with a third degree polynomial dependency for day-of-year (DOY). With such dependencies removed, the remaining TEC variation could be resolved and attributed to an appropriate mechanism. Lunar phase and apside was investigated in particular, especially the new and full moon phases during perigees when tidal forcing would be most powerful. Lunar tidal forcing on planetary waves is also examined as being physically responsible for setting up conditions that may give rise to SSWs and ionospheric anomalies. Preliminary results suggest that such anomalies may be enhanced in intensity during the full or new moon and even more so during perigee by different amounts depending on whether the SSW is a major (40-60%) or minor (20-45%) event.
Thermal anomalies in stressed Teflon.
Lee, S. H.; Wulff, C. A.
1972-01-01
In the course of testing polytetrafluoroethylene (Teflon) as a calorimetric gasketing material, serendipity revealed a thermal anomaly in stressed film that occurs concomitantly with the well-documented 25 C transition. The magnitude of the excess energy absorption - about 35 cal/g - is suggested to be related to the restricted thermal expansion of the film.
Ramotoroko, Calistus D.; Ranganai, Rubeni T.; Nyabeze, Peter
2016-11-01
The main goal of this study is to use suitably processed potential field data between longitude 24°E to 26°E and latitude 25°S to 26.5°S to gain a better geological and structural understanding of the extension of the Madibe-Kraaipan granite-greenstone terrane in southeast Botswana. Specifically, 150 new gravity measurements at 2-4 km intervals are reduced and later merged with existing gravity data in Botswana and South Africa for an integrated crustal interpretation with regional aeromagnetic data. Gravity and aeromagnetic anomalies of the region present partly coincident medium to high amplitude regions alternating with low zones. Analysis of the data revealed the existence of relatively narrow Nsbnd S trending rocks of dense and high magnetic intensity extending to the village of Mmathethe, corresponding to the northern extent of the Kraaipan greenstone belt. Much of the north-central area forms a broad magnetic low and gravity high implying Kraaipan metavolcanic rocks are more extensively developed in this area than previously recognized, under a blanket of Kalahari sediments that are ∼55 m thick as indicated by borehole data. The whole area lies within an ENE-trending Pre-Transvaal dyke swarm visible on the regional aeromagnetic data and much clearer on (proprietary) high resolution aeromagnetic data. The derivative and analytic signal techniques applied for both gravity and magnetic data spatially map the greenstone belt and multiple granite plutons very well. Depth estimates obtained by the 3D Euler method in combination with two-dimensional power spectrum technique locate the high magnetic intensity horizon at around 4.0 km. The depths were further confirmed by gravity model results along two profiles across the granite-greenstone terrane in Botswana and South Africa in a W-E direction. The models show generally steep-sided bodies of comparable width with a maximum depth extent of 4.7 km for the greenstones and 4.4 km for the younger plutons. The
Oda, Ichiro
2016-01-01
We propose a topological model of induced gravity (pregeometry) where both Newton's coupling constant and the cosmological constant appear as integration constants in solving field equations. The matter sector of a scalar field is also considered, and by solving field equations it is shown that various types of cosmological solutions in the FRW universe can be obtained. A detailed analysis is given of the meaning of the BRST transformations, which make the induced gravity be a topological field theory, by means of the canonical quantization analysis, and the physical reason why such BRST transformations are needed in the present formalism is clarified. Finally, we propose a dynamical mechanism for fixing the Lagrange multiplier fields by following the Higgs mechanism. The present study clearly indicates that the induced gravity can be constructed at the classical level without recourse to quantum fluctuations of matter and suggests an interesting relationship between the induced gravity and the topological qu...
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (55,907 records) were gathered by various governmental organizations (and academia) using a variety of methods. This data base was received...
Zinoviev, Yury M
2012-01-01
The equations of the relativistic causal Newton gravity law for the planets of the solar system are studied in the approximation when the Sun rests at the coordinates origin and the planets do not iteract between each other.
Infrared Modifications Of Gravity
Rombouts, J
2005-01-01
In this thesis, we study theories that modify gravity at very large distances. Motivated by recent observations in cosmology, such as the dimming of type Ia supernovae and flattening of rotation curves of galaxies, we study two classes of theories that attempt to explain these observations as due to a change in the laws of gravity at large distances rather than due to the presence of new forms of exotic energy and matter. The first class of theories is massive gravity, obtained by adding a mass term to the action for the gravitational fluctuation in Einstein's general relativity. The second class of models we study are braneworlds that provide infrared modified gravity, in specific the Dvali-Gabadadze-Porrati model and its extension to higher codimensional branes. We stress in our discussion the field theoretical consistency, both classically and quantum-mechanically, of these models.
Capozziello, Salvatore
2011-01-01
Extended Theories of Gravity can be considered a new paradigm to cure shortcomings of General Relativity at infrared and ultraviolet scales. They are an approach that, by preserving the undoubtedly positive results of Einstein's Theory, is aimed to address conceptual and experimental problems recently emerged in Astrophysics, Cosmology and High Energy Physics. In particular, the goal is to encompass, in a self-consistent scheme, problems like Inflation, Dark Energy, Dark Matter, Large Scale Structure and, first of all, to give at least an effective description of Quantum Gravity. We review the basic principles that any gravitational theory has to follow. The geometrical interpretation is discussed in a broad perspective in order to highlight the basic assumptions of General Relativity and its possible extensions in the general framework of gauge theories. Principles of such modifications are presented, focusing on specific classes of theories like f (R)-gravity and scalar-tensor gravity in the metric and Pala...
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (65,164 records) were gathered by various governmental organizations (and academia) using a variety of methods. The data base was received...
Bueno, Pablo; Cano, Pablo A.
2016-11-01
We drastically simplify the problem of linearizing a general higher-order theory of gravity. We reduce it to the evaluation of its Lagrangian on a particular Riemann tensor depending on two parameters, and the computation of two derivatives with respect to one of those parameters. We use our method to construct a D -dimensional cubic theory of gravity which satisfies the following properties: (1) it shares the spectrum of Einstein gravity, i.e., it only propagates a transverse and massless graviton on a maximally symmetric background; (2) it is defined in the same way in general dimensions; (3) it is neither trivial nor topological in four dimensions. Up to cubic order in curvature, the only previously known theories satisfying the first two requirements are the Lovelock ones. We show that, up to cubic order, there exists only one additional theory satisfying requirements (1) and (2). Interestingly, this theory is, along with Einstein gravity, the only one which also satisfies (3).
National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (71 records) were gathered by various governmental organizations (and academia) using a variety of methods. This data base was received in...
De Bakker, B V; Bakker, Bas de; Smit, Jan
1994-01-01
We look at gravitational attraction in simplicial gravity using the dynamical triangulation method. On the dynamical triangulation configurations we measure quenched propagators of a free massive scalar field. The masses measured from these propagators show that gravitational attraction is present.
童余德; 边少锋; 蒋东方; 向才炳
2012-01-01
惯性导航系统定位误差随时间积累发散,利用重力场辅助惯性导航已成为组合导航领域的新方向,该技术对实现潜艇无源定位意义重大.首先利用二维高斯基函数对局部离散格网重力异常基准图进行逼近获取其解析表达式,在此基础上对传统相关极值匹配算法进行重新建模,采用拟牛顿BFGS非线性寻优方法对该模型进行解算,最终完成基于连续解析形式重力异常基准图的相关极值匹配算法设计.为进一步提高算法性能进行以下两点改进:(1)采用TERCOM算法进行预匹配以缩小寻优范围提高寻优速度；(2)采用差分法减小实测过程中E(o)tv(o)s效应对重力匹配的影响.最后在2′×2′卫星测高反演重力异常数据库基础上进行了三组对比仿真实验,从实验结果可以看出,在重力测量误差、系统误差及初始定位误差较大的情况下,通过该组合匹配算法获得的匹配定位仍能以较高的精度跟踪真实航迹,且其性能较传统单一匹配算法有较大提高.%The gravity field aided inertial navigation has been applied to correct the drifting errors in the inertial navigation which are accumulated with time and it has become a new research direction in the integrated navigation technology which is significant to implement autonomous and passive navigation of submarines. Firstly, the algorithm to approximate the local grid gravity anomaly map with the 2-D Gauss spline function is proposed. The mathematical model of maximum correlation matching algorithm is redesigned based on this local continuous map and the BFGS method of Quasi-Newton is adopted to solve the non-linear model. Finally, the maximum correlation matching algorithm based on a continuous analytic form of gravity anomaly map is accomplished. Two improvements are used to further improve the efficiency of the new algorithm as follows: (1) TERCOM algorithm is applied to pre-match for the reduction of
On the variability of near-surface screen temperature anomalies in the 20 March 2015 solar eclipse.
Clark, Matthew R
2016-09-28
Near-surface air temperature (NSAT) anomalies during the 20 March 2015 solar eclipse are investigated at 266 UK sites, using operational data. The high density of observing sites, together with the wide range of ambient meteorological conditions, provided an unprecedented opportunity for analysis of the spatial variability of NSAT anomalies under relatively uniform eclipse conditions. Anomalies ranged from -0.03°C to -4.23°C (median -1.02°C). The maximum (negative) anomaly lagged the maximum obscuration by 15 min on average. Cloud cover impacted strongly on NSAT anomalies, with larger anomalies in clear-sky situations (peclipse, the topographical influences on NSAT anomalies were apparently dominated by variations in residual nocturnal inversion strength, as suggested by significant correlations between post-sunrise temperature and NSAT anomaly at clear-sky sites (larger negative anomalies with lower post-sunrise temperatures). The largest NSAT anomaly occurred at a coastal site where flow transitioned from onshore to offshore during the eclipse, in a situation with large coastal temperature gradients associated with antecedent nocturnal cooling.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'.
Gravity inferred subsurface structure of Gadwal Schist belt, Andhra Pradesh
G Ramadass; I B Ramaprasada Rao; N Srinivasulu
2001-03-01
Detailed gravity data collected across the Gadwal schist belt in the state of Andhra Pradesh show an 8.4 mgal residual gravity anomaly associated with meta-sediments/volcanics of the linear NNW-SSE trending schist belt that shows metamorphism from green schist to amphibolite facies. This schist belt is flanked on either side by the peninsular gneissic complex. The elevation and slab Bouguer corrected residual gravity profile data were interpreted using 2-D prism models. The results indicate a synformal structure having a width of 1.8 km at the surface, tapering at a depth of about 2.6 km with a positive density contrast of 0.15 gm/cc with respect to the surrounding peninsular gneissic complex.
Gravity field and internal structure of Mercury from MESSENGER.
Smith, David E; Zuber, Maria T; Phillips, Roger J; Solomon, Sean C; Hauck, Steven A; Lemoine, Frank G; Mazarico, Erwan; Neumann, Gregory A; Peale, Stanton J; Margot, Jean-Luc; Johnson, Catherine L; Torrence, Mark H; Perry, Mark E; Rowlands, David D; Goossens, Sander; Head, James W; Taylor, Anthony H
2012-04-13
Radio tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern hemisphere, several large gravity anomalies, including candidate mass concentrations (mascons), exceed 100 milli-Galileos (mgal). Mercury's northern hemisphere crust is thicker at low latitudes and thinner in the polar region and shows evidence for thinning beneath some impact basins. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/MR(2) = 0.353 ± 0.017, where M and R are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of C(m)/C = 0.452 ± 0.035. A model for Mercury's radial density distribution consistent with these results includes a solid silicate crust and mantle overlying a solid iron-sulfide layer and an iron-rich liquid outer core and perhaps a solid inner core.