Obtained Value (obtained + value)

Distribution by Scientific Domains


Selected Abstracts


DETERMINATION OF FAULT SLIP COMPONENTS USING SUBSURFACE STRUCTURAL CONTOURS: METHODS AND EXAMPLES

JOURNAL OF PETROLEUM GEOLOGY, Issue 3 2004
S-S. Xu
Problems with measuring fault slip in the subsurface can sometimes be overcome by using subsurface structural contour maps constructed from well logs and seismic information. These maps are useful for estimating fault slip since fault motion commonly causes the dislocation of structural contours. The dislocation of a contour is defined here as the distance in the direction of fault strike between two contours which have the same value on both sides of a fault. This dislocation can be estimated for tilted beds and folded beds as follows: (i),If a dip-slip fault offsets a tilted bed, the dislocation (Sc) of contours can be estimated from the vertical component (Sv) of the fault slip and the dip (,) of the bedding according to the following relationship: Sc= Sv/tan ,. Since Sc and , can be measured from a contour map, the vertical component of fault slip can be obtained from this equation. If a strike-slip fault offsets a tilted bed, the dislocation (Scs) of contours is equal to the strike-slip of the fault (Sc), that is, Scs= Ss. (ii),If a fault offsets a symmetric fold, the strike component (Scs) of fault slip and the dislocation of the contours (Sc) can be calculated, respectively, from the equations Scs= (Smax+ Smin) / 2 and Sc= (Smax - Smin) / 2. Smax is the greater total dislocation (Sc+ Scs) of a contour line between the two limbs of the fold and Smin is the smaller total dislocation (Sc - Scs) for the same contour line. In this case, Sv can be also calculated using the obtained value of Sc and the equation Sv= Sc tan ,. Similarly, for an asymmetric fold, the dislocation of contours due to the vertical slip component is Scb= (Smax - Smin)/(n + 1), and the strike-slip component is Ss= Scs= (nSmin+ Smax/(n + 1), where n is the ratio between the values of interlines of the two limbs, and Scb is the dislocation of contours due to the vertical slip component for either of the two limbs (here it is for limb b). In all cases, three conditions are required for the calculation of contour dislocation: (i),the contour lines must be approximately perpendicular to the fault strike; the intersection angle between the fault strike and the strike of bedding should be greater than 65°; (ii),the bed must not be dip more than 35°; and (iii),folding or flexure of the stratigraphic horizons must have occurred before faulting. These methods for determining fault slip from the dislocation of structural contours are discussed using case studies from the Cantarell oilfield complex, Campeche Sound (southern Gulf of Mexico), the Jordan-Penwell Ellenburger oilfield in Texas, and the Wilmington oilfield in California. [source]


A Comparison of the Variability Spectra of Two Genomic Loci in a European Group of Individuals Reveals Fundamental Differences Pointing to Selection or a Population Bottleneck

ANNALS OF HUMAN GENETICS, Issue 3 2007
C. Schmegner
Summary Knowledge about the variability spectra of neutrally evolving sequences in a population is a prerequisite for the identification of genes, which may have been under positive selection during recent human evolution. Here, we report the results of a re-sequencing project of a presumably neutrally evolving chromosome 22 locus with a severely reduced recombination frequency in a group of 24 individuals of German origin. The comparison of these data with the results of a similar analysis of a chromosome 17 locus revealed striking differences, although the same group of individuals was used. For the chromosome 17 locus two well-separated groups of sequences, a positive value of Tajima's D and a TMRCA of 700 000 years were observed. In contrast, the sequences from the chromosome 22 locus were found to be relatively homogeneous, with no deep splits between subgroups; the obtained value for Tajima's D was negative and the TMRCA was only 260 000 years. These discrepancies may be explained by selection or demographic processes. Regarding demography, the most plausible explanation is the assumption of a severe bottleneck in the history of the European population: in the case of the chromosome 17 locus two ancient lineages passed this bottleneck; for the chromosome 22 locus it was only one ancient lineage. [source]


A Haigh,Mallion-Based Approach for the Evaluation of the Intensity Factors of Aromatic Rings

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2006
Cristiano Zonta
Abstract A novel method for the determination of intensity factors of benzenoid systems based on the Haigh,Mallion (HM) theory has been developed. In this paper, the magnetic anisotropy generated by the ring-current effect in polycondensed arenes has been quantitatively calculated as nuclear independent chemical shieldings (NICSs) in a three-dimensional grid of points using the B3LYP/6-31G(d) method implemented in the Gaussian 98 program. The fitting of the calculated values to the HM model gives intensity factors for each ring. A comparison of the obtained values with Schleyer's NICS0 is given. The obtained intensity factors may find application in software using 1H NMR chemical shifts for structure determination.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]


Copper-containing nitrite reductase from Pseudomonas chlororaphis DSM 50135

FEBS JOURNAL, Issue 12 2004
Evidence for modulation of the rate of intramolecular electron transfer through nitrite binding to the type 2 copper center
The nitrite reductase (Nir) isolated from Pseudomonas chlororaphis DSM 50135 is a blue enzyme, with type 1 and type 2 copper centers, as in all copper-containing Nirs described so far. For the first time, a direct determination of the reduction potentials of both copper centers in a Cu-Nir was performed: type 2 copper (T2Cu), 172 mV and type 1 copper (T1Cu), 298 mV at pH 7.6. Although the obtained values seem to be inconsistent with the established electron-transfer mechanism, EPR data indicate that the binding of nitrite to the T2Cu center increases its potential, favoring the electron-transfer process. Analysis of the EPR spectrum of the turnover form of the enzyme also suggests that the electron-transfer process between T1Cu and T2Cu is the fastest of the three redox processes involved in the catalysis: (a) reduction of T1Cu; (b) oxidation of T1Cu by T2Cu; and (c) reoxidation of T2Cu by NO2,. Electrochemical experiments show that azurin from the same organism can donate electrons to this enzyme. [source]