14,051 research outputs found
The surface geometry of inherited joint and fracture trace patterns resulting from active and passive deformation
Hypothetical models are considered for detecting subsurface structure from the fracture or joint pattern, which may be influenced by the structure and propagated to the surface. Various patterns of an initially orthogonal fracture grid are modeled according to active and passive deformation mechanisms. In the active periclinal structure with a vertical axis, fracture frequency increased both over the dome and basin, and remained constant with decreasing depth to the structure. For passive periclinal features such as a reef or sand body, fracture frequency is determined by the arc of curvature and showed a reduction over the reefmound and increased over the basin
Code extraction algorithms which unify slicing and concept assignment
One approach to reverse engineering is to partially automate subcomponent extraction, improvement and subsequent recombination. Two previously proposed automated techniques for supporting this activity are slicing and concept assignment. However, neither is directly applicable in isolation; slicing criteria (sets of program variables) are simply too low level in many cases, while concept assignment typically fails to produce executable subcomponents. This paper introduces a unification of slicing and concept assignment which exploits their combined advantages, while overcoming their individual weaknesses. Our 'concept slices' are extracted using high level criteria, while producing executable subprograms. The paper introduces three ways of combining slicing, and concept assignment and algorithms for each. The application of the concept slicing algorithms is illustrated with a case study from a large financial organisation
Relation of lineaments to sulfide deposits: Bald Eagle Mountain, Centre County, Pennsylvania
The author has identified the following significant results. Discrete areas of finely-fractured and brecciated sandstone float are present along the crest of Bald Mountain and are commonly sites of sulfide mineralization, as evidenced by the presence of barite and limonite gossans. The frequency distributions of the brecciated float as the negative binomial distribution supports the interpretation of a separate population of intensely fractured material. Such zones of concentrated breccia float have an average width of one kilometer with a range from 0.4 to 1.6 kilometers and were observed in a quarry face to have subvertical dips. Direct spatial correlation of the Landsat-derived lineaments to the fractured areas on the ridge is low; however, the mineralized and fracture zones are commonly assymetrical to the lineament positions. Such a systematic dislocation might result from an inherent bias in the float population or could be the product of the relative erosional resistance of the silicified material in the mineralized areas in relation to the erosionally weak material at the stream gaps
Relativistic Poynting Jets from Accretion Disks
A model is developed for relativistic Poynting jets from the inner region of
a disk around a rotating black hole. The disk is initially threaded by a
dipole-like magnetic field. The model is derived from the special relativistic
equation for a force-free electromagnetic field. The ``head'' of the Poynting
jet is found to propagate outward with a velocity which may be relativistic.
The Lorentz factor of the head (Gamma) is found to be dependent on the magnetic
field strength close to the black hole, B_0, the density of the external medium
n_ext, and on the ratio R=r_0/r_g >1, where r_g is the gravitational radius of
the black hole, and r_0 is the radius of the O-point of the initial dipole
field threading the disk. For conditions pertinent to an active galactic
nuclei, Gamma is approximately equal to 8 (10/R)^(1/3) (B_0/10^3 Gauss)^(1/3)
(1/cm^3/n_ext)^(1/6). This model offers an explanation for the observed Lorentz
factors which are of the order of 10 for the parsec-scale radio jets measured
with very long baseline interferometry.Comment: 4 pages, 1 figur
Magnetoresistance of a two-dimensional electron gas in a parallel magnetic field
The conductivity of a two-dimensional electron gas in a parallel magnetic
field is calculated. We take into account the magnetic field induced
spin-splitting, which changes the density of states, the Fermi momentum and the
screening behavior of the electron gas. For impurity scattering we predict a
positive magnetoresistance for low electron density and a negative
magnetoresistance for high electron density. The theory is in qualitative
agreement with recent experimental results found for Si inversion layers and Si
quantum wells.Comment: 4 pages, figures included, PDF onl
Technology utilization in a non-urban region - A measurement of the impact of the Technology Use Studies Center Final report
Technology utilization in agricultural areas and measurement of impact of technology use studies cente
SitesBase: a database for structure-based protein–ligand binding site comparisons
There are many components which govern the function of a protein within a cell. Here, we focus on the molecular recognition of small molecules and the prediction of common recognition by similarity between protein–ligand binding sites. SitesBase is an easily accessible database which is simple to use and holds information about structural similarities between known ligand binding sites found in the Protein Data Bank. These similarities are presented to the wider community enabling full analysis of molecular recognition and potentially protein structure–function relationships. SitesBase is accessible at
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