Probing the nuclear activity with supermassive black holes

We report three new or updated techniques for probing the parameters of active galaxies based on the masses of their central black holes M_BH). First, we derived a near-IR analog of the bulge luminosity versus M_BH relationship. The low scatter makes it a promising new tool to study the black hole demographics. Next, we present relations between M_BH and the10 μm and 2-10 keV nuclear luminosity. They may help to study the M_BH evolution over wide redshift ranges. Finally, we measured M_BH in quasars from z ∼ 3.4 to z ∼ 0.3 to search directly for M_BH growth. Surprisingly, we found no evidence for growth implying that the majority of quasar host galaxies have undergone their last major merger at z ≥ 3. This revised version was published online in August 2006 with corrections to the Cover Date.     

A simple model for lensing by black holes in galactic nuclei

The lensing properties of the Plummer model with a central point mass and external shear are derived, including the image multiplicities, critical curves and caustics. This provides a simple model for a flattened galaxy with a central supermassive black hole. For the Plummer model with black hole, the maximum number of images is four, provided the black hole mass is less than an upper bound which is calculated analytically. This introduces a method to constrain black hole masses by counting images, thus applicable at cosmological distance. With shear, the maximum number of images is six and we illustrate the occurrence of an astroid caustic and two metamorphoses.     

Hard X-ray spectrum of Mkn 421 during the active phase

Spectral measurement of Mkn 421 were made in the hard X-ray energy band of 20–200 keV using a high sensitivity, large area scintillation counter telescope on November 21, 2000 and these coincided with the onset of an active X-ray phase as seen in the ASM counting rates on board RXTE. The observed spectrum can not be fitted to a single power law similar to the PDS data of BeppoSAX. The data can be fitted both by a two component power-law function or a combination of an exponential function with a power law component at the high energies above 80 keV. We identify these components with those arising from the synchrotron self compton and the high energy power-law tail arising from the upgrading of the thermal photons due to multiple Compton scattering a la Cyg X-1. A comparison with the earlier data clearly suggests a spectral variability in the hard X-ray spectrum of the source. We propose a continuously flaring geometry for the source as the underlying mechanism for energy release.     

First U–Pb SHRIMP age of the Hauterivian stage, Neuquén Basin, Argentina

A high-resolution ion-microprobe (SHRIMP) U–Pb zircon age from a tuff layer intercalated in the ammonoid bearing sedimentary succession of the Neuquén Basin in Argentina provides a robust geochronologic date to add to the absolute ages and to improve the relative chronology of the Early Cretaceous Hauterivian stage. The tuff layer appears interbedded between shales of the upper member (Agua de la Mula) of the Agrio Formation within the Spitidiscus riccardii ammonoid zone (base of the Late Hauterivian) yielding a date of 132.5 ± 1.3 Ma. This date confirms and supports an accurate correlation between the ammonoid biostratigraphy of the Neuquén Basin with the Western Mediterranean Province of the Tethys during the Early Cretaceous and matches with the most recently published time scale. It also casts doubts on the validity of K–Ar ages on glauconite-grains recently reported from the Lower Cretaceous of the Vocontian Basin of France.     

Estradiol and estriol suppress CYP1A expression in rainbow trout primary hepatocytes

Hepatic levels of the pollutant inducible enzyme, CYP1A, are strongly suppressed in spawning female fish, a phenomenon attributed to high plasma levels of the female sex steroid hormone, estradiol. To evaluate the contribution of estrogen metabolites to estradiol-mediated CYP1A regulation, we treated primary hepatocytes isolated from juvenile rainbow trout (Oncorhynchus mykiss) with vehicle, 17beta-estradiol, or the estrogen metabolite, estriol, alone and in combination with each other and with the potent CYP1A inducer, benzo[a]pyrene (B[a]P). We found dose-dependent suppression of B[a]P-induced CYP1A activity by both steroids relative to controls. At 10(-7) M doses, estradiol and estriol suppressed B[a]P-induced CYP1A activity by 3- and 2-fold, respectively. Although not statistically significant, mean basal CYP1A activity levels were 15- and 13-fold lower in estradiol and estriol treated hepatocytes, respectively, relative to vehicle treated controls. Combining doses of estradiol and estriol failed to produce synergistic suppression of either basal or B[a]P-induced CYP1A activity relative to treatment with either steroid alone. The observed suppression is well below the often strong suppression observed in spawning female fish. We conclude that factors in addition to estradiol and estriol are likely involved in producing sexual dimorphism in CYP1A expression observed in spawning fish.     

Application of the first internal transcribed spacer(ITS-1) of ribosomal DNA as a molecular marker to population analysis in farrer''s scallop Chlamys farreri

Sequence variation of the first internal transcribed spacer of ribosomal DNA （ ITS - 1 ） was examined and its application to the study of genetic variation was explored in four populations of farter＇ s scallop Chlamys farreri. ITS - 1 fragments, with a length of about 300 bp,of 78 individuals collected from Dalian, Qingdao, Yantai in China and Korea respectively were amplified via PCR, cloned and sequenced. Intra-genomic variation was examined by sequencing several clones of single individuals. Alignment and polymorphism analysis detected 44 haplotypes and 50 polymorphic sites which consist of 30 substitutions and 20 indels, indicating a high level of polymorphisms. Sequence analysis also showed a very low level of intra-individual variation. All these features validated the feasibility of application of ITS - 1 fragment to population analysis. Polymorphism analysis showed that the Korea sample has the richest genetic variation, followed by Yantai and Qingdao samples. AMOVA （analysis of molecular variance） showed that the majority （96.26%） of genetic variation was distributed within populations and 3.74% resulted from among populations, but with P 〈 0.05 （ = 0.042）, indicating that the populations in this study have significant divergence. This output was basically concordant with the result arising from RAPD data and different from that from mitochondrial 16S rDNA sequence data. Discussion on this inconsistency was made accordingly.     

Prediction of UT1–UTC,LOD and AAM χ<Subscript>3</Subscript> by combination of least-squares and multivariate stochastic methods

This article presents the application of a multivariate prediction technique for predicting universal time (UT1–UTC), length of day (LOD) and the axial component of atmospheric angular momentum (AAM χ ₃). The multivariate predictions of LOD and UT1–UTC are generated by means of the combination of (1) least-squares (LS) extrapolation of models for annual, semiannual, 18.6-year, 9.3-year oscillations and for the linear trend, and (2) multivariate autoregressive (MAR) stochastic prediction of LS residuals (LS + MAR). The MAR technique enables the use of the AAM χ ₃ time-series as the explanatory variable for the computation of LOD or UT1–UTC predictions. In order to evaluate the performance of this approach, two other prediction schemes are also applied: (1) LS extrapolation, (2) combination of LS extrapolation and univariate autoregressive (AR) prediction of LS residuals (LS + AR). The multivariate predictions of AAM χ ₃ data, however, are computed as a combination of the extrapolation of the LS model for annual and semiannual oscillations and the LS + MAR. The AAM χ ₃ predictions are also compared with LS extrapolation and LS + AR prediction. It is shown that the predictions of LOD and UT1–UTC based on LS + MAR taking into account the axial component of AAM are more accurate than the predictions of LOD and UT1–UTC based on LS extrapolation or on LS + AR. In particular, the UT1–UTC predictions based on LS + MAR during El Niño/La Niña events exhibit considerably smaller prediction errors than those calculated by means of LS or LS + AR. The AAM χ ₃ time-series is predicted using LS + MAR with higher accuracy than applying LS extrapolation itself in the case of medium-term predictions (up to 100 days in the future). However, the predictions of AAM χ ₃ reveal the best accuracy for LS + AR.     

Structural evolution of the Bayanhongor region, west-central Mongolia

Most of previous models suggest that the Central Asia Orogenic Belt grew southward in the Phanerozoic. However, in the Bayanhongor region in west-central Mongolia, volcanic arc, accretionary prism, ophiolite, and passive margin complexes accreted northeastward away from the Baydrag micro-continent, and hence the region constitutes the southwestern part of a crustal-scale syntaxis close to the west. The syntaxis should be original, because presumably reorientation due to strike-slip faulting can be ignored. It is reconfirmed that the Baydrag eventually collided with another micro-continent (the Hangai) to the northeast. A thick sedimentary basin developed along the southern passive margin of the Hangai micro-continent. This region is also characterized by an exhumed metamorphosed accretionary complex and a passive margin complex, which are both bounded by detachment faults as well as basal reverse faults which formed simultaneously as extrusion wedges. This part of the Central Asia Orogenic Belt lacks exhumed crystalline rocks as observed in the Himalayas and other major collisional orogenic belts. In addition, we identified two phases of deformation, which occurred at each phase of zonal accretion as D1 through Cambrian and Devonian, and a synchronous phase of final micro-continental collision of Devonian as D2. The pre-collisional ocean was wide enough to be characterized by a mid-ocean ridge and ocean islands. Two different structural trends of D1 and D2 are observed in accretionary complexes formed to the southwest of the late Cambrian mid-ocean ridge. That is, the relative plate motions on both sides of the mid-ocean ridge were different. Accretionary complexes and passive margin sediments to the northeast of the mid-ocean ridge also experienced two periods of deformation but show the same structural trend. Unmetamorphosed cover sediments on the accretionary prism and on the Hangai micro-continent experienced only the D2 event due to micro-continental collision. These unmetamorphosed sediments form the hanging walls of the detachment faults. Moreover, they were at least partly derived from an active volcanic arc formed at the margin of the Baydrag micro-continent.     

Elastic properties and stability of coexisting 3T and 2M 1 phengite polytypes

The elastic properties of coexisting natural 3T and 2M ₁ phengite samples (Cima Pal, Sesia Zone; Val Savenca; Western Alps, Italy) with similar chemical compositions have been studied by room temperature–high pressure powder diffraction, using synchrotron radiation on the ID9A beam-line at ESRF (Grenoble, France). The P–V curves have been modelled by the Birch–Murnaghan model; a third-order expansion fitted to the experimental data yields for 3T and 2M ₁ K ₀=60.4(±0.7) GPa, K′=5.79(±0.11) at V ₀=703.8851 ų, and K ₀=57.3(±1.0) GPa, K′=6.97(±0.24) at V ₀=938.8815 ų, respectively. The relative stability of 3T vs. 2M ₁ has been explored as a function of pressure and temperature in terms of configuration and deformation contributions to the Gibbs energy, using the elastic properties determined here and other thermodynamic parameters from earlier investigations. The results presented agree with the hypothesis of stability of the 3T polytype in the high pressure regime.     

C1相干算法及其在三维地震资料处理解释中的应用

C1相干算法是计算每道的横测线和相邻纵测线的互相关，依据相干值来判断地层和岩性的横向不均匀性。根据互相关原理，提出了相干体算法中二维和三维C1算法的内容及其具体实现。通过对实际三维地震资料的处理，结合已知地质资料，证明C1相干技术在三维地震资料的断层解释方面有着明显的效果。