While these samples are representative of the content of Science.gov,

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of Science.gov

to obtain the most current and comprehensive results.

Last update: August 15, 2014.

1

Developing global climate anomalies suggest potential disease risks for 2006 – 2007

BACKGROUND: El Niño\\/Southern Oscillation (ENSO) related climate anomalies have been shown to have an impact on infectious disease outbreaks. The Climate Prediction Center of the National Oceanic and Atmospheric Administration (NOAA\\/CPC) has recently issued an unscheduled El Niño advisory, indicating that warmer than normal sea surface temperatures across the equatorial eastern Pacific may have pronounced impacts on global tropical precipitation

Assaf Anyamba; Jean-Paul Chretien; Jennifer Small; Compton J Tucker; Kenneth J Linthicum

2006-01-01

2

ERIC Educational Resources Information Center

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,…

Online-Offline, 1999

1999-01-01

3

Singularity analysis of potential fields to enhance weak anomalies

NASA Astrophysics Data System (ADS)

Geoanomalies generally are nonlinear, non-stationary and weak, especially in the land cover areas, however, the traditional methods of geoanomaly identification are usually based on linear theory. In past two decades, many power-law function models have been developed based on fractal concept in mineral exploration and mineral resource assessment, such that the density-area (C-A) model and spectrum-area model (S-A) suggested by Qiuming Cheng have played important roles in extracting geophysical and geochemical anomalies. Several power-law relationships are evident in geophysical potential fields, such as field value-distance, power spectrum-wave number as well as density-area models. The singularity index based on density-area model involves the first derivative transformation of the measure. Hence, we introduce the singularity analysis to develop a novel high-pass filter for extracting gravity and magnetic anomalies with the advantage of scale invariance. Furthermore, we suggest that the statistics of singularity indices can provide a new edge detection scheme for the gravity or magnetic source bodies. Meanwhile, theoretical magnetic anomalies are established to verify these assertions. In the case study from Nanling mineral district in south China and Qikou Depression in east China, compared with traditional geophysical filtering methods including multiscale wavelet analysis and total horizontal gradient methods, the singularity method enhances and extracts the weak anomalies caused by buried magmatic rocks more effectively, and provides more distinct boundary information of rocks. Moreover, the singularity mapping results have good correspondence relationship with both the outcropping rocks and known mineral deposits to support future mineral resource exploration. The singularity method based on fractal analysis has potential to be a new useful theory and technique for processing gravity and magnetic anomaly data.

Chen, G.; Cheng, Q.; Liu, T.

2013-12-01

4

Modeling of self-potential anomalies near vertical dikes.

The self-potential (SP) Green's function for an outcropping vertical dike is derived from solutions for the dc resistivity problem for the same geometry. The Green's functions are numerically integrated over rectangular source regions on the contacts between the dike and the surrounding material to obtain the SP anomaly. The analysis is valid for thermoelectrical source mechanisms. Two types of anomalies can be produced by this geometry. When the two source planes are polarized in opposite directions, a monopolar anomaly is produced. This corresponds to the thermoelectrical properties of the dike being in contrast with the surrounding material. When the thermoelectric coefficients change monotonically across the dike, a dipolar anomaly is produced. In either case positive and negative anomalies are possible, and the greatest variation in potential will occur in the most resistive regions. -Author

Fitterman, D. V.

1983-01-01

5

Tomography of self-potential anomalies of electrochemical nature

NASA Astrophysics Data System (ADS)

Ore deposits and buried metals like pipelines behave as dipolar electrical geobatteries in which the source is due to (1) variation of the redox potential with depth, (2) oxido-reduction reactions acting at the ore body/groundwater contact, and (3) migration of electrons in the ore body itself between the reducing and oxidizing zones. This polarization mechanism is responsible for an electrical field at the ground surface, the so-called self-potential anomaly. A new quick-look tomographic algorithm is developed to locate electrical dipolar sources in the subsurface of the Earth from the analysis of these self-potential signals. We applied this model to the self-potential anomaly discussed by Stoll et al. [1995] in the vicinity of the KTB-boreholes drilled during the Continental Deep Drilling Project in Germany. The source of this self-potential signal is related to the presence of massive graphite veins associated with steeply inclined fault zones within the gneisses and observed in the KTB-boreholes.

Revil, A.; Ehouarne, L.; Thyreault, E.

6

NASA Technical Reports Server (NTRS)

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.

Rapp, Richard H.; Pavlis, Nikolaos

1989-01-01

7

Random matrix model at nonzero chemical potentials with anomaly effects

NASA Astrophysics Data System (ADS)

Phase diagram of the chiral random matrix model with U(1)A breaking term is studied with the quark chemical potentials varied independently at zero temperature by taking the chiral and meson condensates as the order parameters. Although, without the U(1)A breaking term, chiral transition of each flavor can happen separately responding to its chemical potential, the U(1)A breaking terms mix the chiral condensates and correlate the phase transitions. In the three-flavor case, we find that there are mixings between the meson and chiral condensates due to the U(1)A anomaly, which makes the meson condensed phase more stable. Increasing the hypercharge chemical potential (?Y) with the isospin and quark chemical potentials (?I,?q) kept small, we observe that the kaon-condensed phase becomes the ground state and at the larger ?Y the pion-condensed phase appears unexpectedly, which is caused by the competition between the chiral restoration and the meson condensation. The similar happens when ?Y and ?I are exchanged, and the kaon-condensed phase becomes the ground state at larger ?I below the full chiral restoration.

Fujii, H.; Sano, T.

2011-01-01

8

Quantitative Interpretation of Self-Potential Anomalies of Some Simple Geometric Bodies

We have developed a new numerical method to determine the shape (shape factor), depth, polarization angle, and electric dipole moment of a buried structure from residual self-potential (SP) anomalies. The method is based on defining the anomaly value at the origin and four characteristic points and their corresponding distances on the anomaly profile. The problem of shape determination from residual

E. M. Abdelrahman; K. S. Soliman; E. R. Abo-Ezz; K. S. Essa; T. M. El-Araby

2009-01-01

9

Rapid fluid disruption: A source for self-potential anomalies on volcanoes

Self-potential (SP) anomalies observed above suspected magma reservoirs, dikes, etc., on various volcanoes (Kilauea, Hawaii; Mount Unzen, Japan; Piton de la Fournaise, Reunion Island, Miyake Jima, Japan) result from transient surface electric fields of tens of millivolts per kilometer and generally have a positive polarity. These SP anomalies are usually attributed to electrokinetic effects where properties controlling this process are poorly constrained. We propose an alternate explanation that contributions to electric fields of correct polarity should be expected from charge generation by fluid vaporization/disruption. As liquids are vaporized or removed as droplets by gas transport away from hot dike intrusions, both charge generation and local increase in electrical resistivity by removal of fluids should occur. We report laboratory observations of electric fields in hot rock samples generated by pulses of fluid (water) through the rock at atmospheric pressure. These indicate the relative amplitudes of rapid fluid disruption (RFD) potentials and electrokinetic potentials to be dramatically different and the signals are opposite in sign. Above vaporization temperatures, RFD effects of positive sign in the direction of gas flow dominate, whereas below these temperatures, effects of negative sign dominate. This suggests that the primary contribution to observed self-potential anomalies arises from gas-related charge transport processes at temperatures high enough to produce vigorous boiling and vapor transport. At lower temperatures, the primary contribution is from electrokinetic effects modulated perhaps by changing electrical resistivity and RFD effects from high-pressure but low-temperature CO2 and SO2 gas flow ripping water molecules from saturated crustal rocks. If charge generation is continuous, as could well occur above a newly emplaced dike, positive static potentials will be set up that could be sustained for many years, and the simplest method for identifying these hot, active regions would be to identify the SP anomalies they generate.

Johnston, M. J. S.; Byerlee, J. D.; Lockner, D.

2001-01-01

10

A Least-squares Approach to Shape Determination from Residual Self-potential Anomalies

We have developed a least-squares minimization approach to determine the shape (shape-factor) of a buried polarized body from a residual self-potential anomaly profile. By defining the zero anomaly distance and the anomaly value at the origin on the profile, the problem of the shape-factor determination is transformed into the problem of finding a solution of a nonlinear equation of the

E. M. Abdelrahman; T. M. El-Araby; A. A. Ammar; H. I. Hassanein

1997-01-01

11

Quantitative Interpretation of Self-Potential Anomalies of Some Simple Geometric Bodies

We have developed a new numerical method to determine the shape (shape factor), depth, polarization angle, and electric dipole\\u000a moment of a buried structure from residual self-potential (SP) anomalies. The method is based on defining the anomaly value\\u000a at the origin and four characteristic points and their corresponding distances on the anomaly profile. The problem of shape\\u000a determination from residual

E. M. Abdelrahman; K. S. Soliman; E. R. Abo-Ezz; K. S. Essa; T. M. El-Araby

2009-01-01

12

Potential Mars 2001 Sites Coincident with Magnetic Anomalies

NASA Technical Reports Server (NTRS)

Of the areas that meet the engineering criteria for MSP 01, only two are coincident with magnetic anomalies measured by the MAG/ER instrument on MGS. Area A is centered on about 10 deg S, 202 deg W and extends from about 7.5 deg S to 15 S. This area is associated with three bands of magnetic anomalies, two with positive values surrounding an area with negative values. Area B corresponds with a circular high positive magnetic anomaly and is centered at 13.5 deg S, 166 deg W. In addition to magnetic anomalies, the proposed sites have other attributes that make then attractive from of standpoint of meeting the objectives of the Mars Program. The landing site candidates meet the engineering requirements outlined on the Mars '01 landing site page htip://mars.jpl.nasa.gov/2001/landingsite. These are (source of data in parentheses): latitude between 3 deg N and 12 deg S, rock abundance between 5-10% (IRTM), fine-component thermal inertia > 4 cgs units (IRTM), topography < 2.5 km (MOLA). There are three exceptions: 1) Area B contains sites that lie up to about 15 deg S, 2) some sites are considered that have rock abundance values of 3-13%. 3) High resolution Viking coverage may not be available. These exceptions will be noted.

Gilmore, M. S.

1999-01-01

13

How attractive interaction changes water-like anomalies of a core-softened model potential

NASA Astrophysics Data System (ADS)

Understanding the origin of anomalous properties of water is of prime importance. A pertinent question in this respect is: whether tetrahedral orientational interaction is a prerequisite for the manifestation of water-like anomalies. Recently it is shown that spherically symmetric potentials with two length scales, popularly known as coresoftened potentials yield water-like anomalies. In the present study, we investigate the effect of attractive interactions among the particles on the existence and location of density anomaly in the temperature-density (T-?) plane. Using a suitable form of the core-softened potential, we employ extensive molecular dynamic simulations to understand microscopic origin of the density anomaly in terms of local structure of the model fluid. We observe that with the increase of the attractive interaction, the density anomaly region shifts towards higher densities and higher temperatures.

Pant, Shashank; Gera, Tarun; Choudhury, Niharendu

2014-04-01

14

LAAS Study of Slow-Moving Ionosphere Anomalies and Their Potential Impacts

Triggered by several severe ionosphere storms that have occurred in recent years, research has been done to studying those anomalies, the physics behind them, and their potential impact on augmented GNSS users. In previous work (1-5), it was found that such ionosphere anomalies can threaten LAAS users under extreme conditions. To determine this, a spatial-gradient \\

Ming Luo; Sam Pullen; Seebany Datta-Barua; Godwin Zhang; Todd Walter; Per Enge

2005-01-01

15

A new approach is proposed in order to interpret spontaneous potential (self-potential) anomalies related to simple geometric-shaped\\u000a models such as sphere, horizontal cylinder, and vertical cylinder. This approach is mainly based on using neural network inversion\\u000a of SP anomalies, particularly modular algorithm, for estimating the parameters of different simple geometrical bodies. However,\\u000a Hilbert transforms are involved to determine the origin

Mansour A. Al-Garni

2010-01-01

16

NASA Astrophysics Data System (ADS)

If equatorial sediments form characteristic deposits around the equator, they may help to resolve the amount of northwards drift of the Pacific tectonic plate. Relevant to this issue, it has been shown that 230Th has been accumulating on the equatorial seabed faster than its production from radioactive decay in the overlying water column during the Holocene (Marcantonio et al. in Paleoceanography 16:260-267, 2001). Some researchers have argued that this reflects the deposition of particles with adsorbed 230Th carried by bottom currents towards the equator ("focusing"). If correct, this effect may combine with high pelagic productivity, which is also centered on the equator, to yield a characteristic signature of high accumulation rates marking the paleoequator in older deposits. Here we evaluate potential evidence that such an equatorial feature existed in the geological past. Seismic reflection data from seven meridional transects suggest that a band of equatorially enhanced accumulation of restricted latitude was variably developed, both spatially and temporally. It is absent in the interval 14.25-20.1 Ma but is well developed for the interval 8.55-14.25 Ma. We also examined eolian dust accumulation rate histories generated from scientific drilling data. A dust accumulation rate anomaly near the modern equator, which is not obviously related to the inter-tropical convergence zone, is interpreted as caused by focusing. Accumulation rates of Ba and P2O5 (proxies of export production) reveal a static equatorial signature, which suggests that the movement of the Pacific plate over the period 10-25 Ma was modest. The general transition from missing to well-developed focusing signatures around 14.25 Ma in the seismic data coincides with the mid-Miocene development of the western boundary current off New Zealand. This current supplies the Pacific with deep water from Antarctica, and could therefore imply a potential paleoceanographic or paleoclimatic origin. At 10.05-14.25 Ma, the latitudes of the seismic anomalies are up to ~2° different from the paleoequator predicted by Pacific plate-hotspot models, suggesting potentially a small change in the hotspot latitudes relative to the present day (although this inference depends on the precise form of the deposition around the equator). The Ba and P2O5 anomalies, on the other hand, are broadly compatible with plate models predicting slow northward plate movement over 10-25 Ma.

Mitchell, Neil C.; Dubois, Nathalie

2014-03-01

17

A new method for complete quantitative interpretation of self-potential anomalies

A least-squares minimization approach to determine the shape of a buried polarized body from a self-potential (SP) anomaly profile has been developed. By defining the anomaly value at three points on the profile, one at the origin and the others at any two symmetrical points around the origin, the problem of the shape-factor determination is transformed into the problem of

Hesham M. El-Araby

2004-01-01

18

Random matrix model at nonzero chemical potentials with anomaly effects

Phase diagram of the chiral random matrix model with U(1){sub A} breaking term is studied with the quark chemical potentials varied independently at zero temperature by taking the chiral and meson condensates as the order parameters. Although, without the U(1){sub A} breaking term, chiral transition of each flavor can happen separately responding to its chemical potential, the U(1){sub A} breaking

H. Fujii; T. Sano

2011-01-01

19

Random matrix model at nonzero chemical potentials with anomaly effects

Phase diagram of the chiral random matrix model with U(1)A breaking term is studied with the quark chemical potentials varied independently at zero temperature by taking the chiral and meson condensates as the order parameters. Although, without the U(1)A breaking term, chiral transition of each flavor can happen separately responding to its chemical potential, the U(1)A breaking terms mix the

H. Fujii; T. Sano

2011-01-01

20

Inversion of Self Potential Anomalies with Multilayer Perceptron Neural Networks

NASA Astrophysics Data System (ADS)

This study investigates the inverse solution on a buried and polarized sphere-shaped body using the self-potential method via multilayer perceptron neural networks (MLPNN). The polarization angle (?), depth to the centre of sphere (h), electrical dipole moment (K) and the zero distance from the origin (x 0) were estimated. For testing the success of the MLPNN for sphere model, parameters were also estimated by the traditional Damped Least Squares (Levenberg-Marquardt) inversion technique (DLS). The MLPNN was first tested on a synthetic example. The performance of method was also tested for two S/N ratios (5 % and 10 %) by adding noise to the same synthetic data, the estimated model parameters with MLPNN and DLS method are satisfactory. The MLPNN also applied for the field data example in ?zmir, Urla district, Turkey, with two cross-section data evaluated by MLPNN and DLS, and the two methods showed good agreement.

Kaftan, Ilknur; S?nd?rg?, Petek; Akdemir, Özer

2014-02-01

21

Nonrelativistic inverse square potential, scale anomaly, and complex extension

The old problem of a singular, inverse square potential in nonrelativistic quantum mechanics is treated employing a field-theoretic, functional renormalization method. An emergent contact coupling flows to a fixed point or develops a limit cycle depending on the discriminant of its quadratic beta function. We analyze the fixed points in both conformal and nonconformal phases and perform a natural extension of the renormalization group analysis to complex values of the contact coupling. Physical interpretation and motivation for this extension is the presence of an inelastic scattering channel in two-body collisions. We present a geometric description of the complex generalization by considering renormalization group flows on the Riemann sphere. Finally, using bosonization, we find an analytical solution of the extended renormalization group flow equations, constituting the main result of our work.

Moroz, Sergej [Institut fuer Theoretische Physik Universitaet Heidelberg, Philosophenweg 16, D-69120 Heidelberg (Germany)], E-mail: s.moroz@thphys.uni-heidelberg.de; Schmidt, Richard [Physik Department, Technische Universitaet Muenchen, James-Franck-Strasse, D-85748 Garching (Germany)

2010-02-15

22

Remote energetic neutral atom imaging of electric potential over a lunar magnetic anomaly

NASA Astrophysics Data System (ADS)