X-ray single-crystal and Raman study of knorringite,Mg3(Cr1.58Mg0.21Si0.21)Si3O12, synthesized at 16 GPa and 1,600 °C     

Elena A. Bykova  Andrey V. Bobrov  Ekaterina A. Sirotkina  Luca Bindi  Sergey V. Ovsyannikov  Leonid S. Dubrovinsky  Yuriy A. Litvin 《Physics and Chemistry of Minerals》2014,41(4):267-272

The crystal structure of a knorringite-type compound, Mg₃(Cr_1.58Mg_0.21Si_0.21)Si₃O₁₂, synthesized in a multi-anvil press at P = 16 GPa and T = 1,600 °C, was refined from single-crystal X-ray diffraction data up to R = 2.36 % for 314 independent reflections. Garnet was found to be cubic and have space group Ia $\overline{3}$ d, with the unit cell parameters a = 11.5718 (1) Å, V = 1,549.54 (2) Å³. The knorringite crystal studied contains 21 mol% of majorite end-member. The structural characterization of knorringitic garnet is important because the study of its thermodynamic constants provides new constraints on thermobarometry of peridotitic garnet assemblages of the lowermost upper mantle. The Raman spectra of synthetic knorringite have been obtained for the first time.  相似文献   

Copepods in Hypersaline Waters Worldwide:Diversity,Environmental,Social,and Economic Roles     

Elena ANUFRIIEVA 《《地质学报》英文版》2014,88(Z1):43-45

正1 Introduction Copepods are a group of small crustaceans,which play an important ecological role in aquatic ecosystems.They occupy different ecological niches in aquatic food webs,contributes to biogenic element cycles,and transfer of organic matter from primary producers to higher secondary consumers.Copepods also have the potential to  相似文献   

An Integrated Study to Analyze Salt Lake Microbial Community Structure(Novosibirsk Oblast,Russia)     

Alla BRYANSKAYA  Alexey ROZANOV  Tatyana MALUP  Taisiya ALESHINA  Elena LAZAREVA  Oxana TARAN  Tatyana GORYACHKOVSKAYA  Vladimir IVANISENKO  Sergey PELTEK 《《地质学报》英文版》2014,88(Z1):61-62

正Salt Lake is one of the lakes in the system,consisting of a huge amount of salt and bitter-salty lakes in Novosibirsk Oblast and Altai Krai.These lakes are unique and highly unstable systems where the parameters of geochemical  相似文献   

Long-term Changes in the Saline Lake Qarun(Egypt)     

Gamal EL-SHABRAWY  Mohamed GOHAR  Mousa GERMOUSH  Elena ANUFRIIEVA  Nickolai SHADRIN 《《地质学报》英文版》2014,88(Z1):180-182

正1 Introduction There is now ample evidence of the impacts of the recent climate change and anthropogenic activities on different saline lake ecosystems.All over the world salt lakes are threatened by climate change,water diversions upstream for agricultural purposes,watershed changes,introduction of aliens,etc.that result in catastrophic  相似文献   

Modelling the interseismic deformation of a thrust system: seismogenic potential of the Southern Alps     

Salvatore Barba  Debora Finocchio  Elena Sikdar  Pierfrancesco Burrato 《地学学报》2013,25(3):221-227

This article focuses on the Montello thrust system in the Eastern Southern Alps as a potential seismogenic source. This system is of particular interest because of its lack of historical seismicity. Nevertheless, the system is undergoing active deformation. We developed a finite‐element model using visco‐elasto‐plastic rheology. The free parameters of the model (essentially, the locking status of the three thrusts included in the study), were constrained by matching the observed horizontal GPS and vertical levelling data. We show that the amount of interseismic fault locking, and thus the seismic potential, is not necessarily associated with the fastest‐slipping faults. More specifically, the locked Bassano thrust has a greater seismic potential than the freely slipping Montello thrust. The findings suggest that faults with subtle evidence of Quaternary activity should be carefully considered when creating seismic hazard maps.  相似文献   

Local And Global Diffusion Along Resonant Lines in Discrete Quasi-integrable Dynamical Systems     

Claude Froeschlé  Massimiliano Guzzo  Elena Lega 《Celestial Mechanics and Dynamical Astronomy》2005,92(1-3):243-255

We detect and measure diffusion along resonances in a quasi-integrable symplectic map for different values of the perturbation parameter. As in a previously studied Hamiltonian case (Lega et al., 2003) results agree with the prediction of the Nekhoroshev theorem. Moreover, for values of the perturbation parameter slightly below the critical value of the transition between Nekhoroshev and Chirikov regime we have also found a diffusion of some orbits along macroscopic portions of the phase space. Such a diffusion follows in a spectacular way the peculiar structure of resonant lines.  相似文献   

A comprehensive study of reported high-metallicity giant H ii regions – II. Ionizing stellar populations     

Marcelo Castellanos  Angeles I. Díaz  Elena Terlevich † 《Monthly notices of the Royal Astronomical Society》2002,337(2):540-552

  相似文献   

Narrow-band CCD photometry of giant H ii regions     

Guillermo Bosch †  Elena Terlevich ‡  Roberto Terlevich § 《Monthly notices of the Royal Astronomical Society》2002,329(3):481-496

We have obtained accurate CCD narrow-band Hβ and Hα photometry of giant H  ii regions (GEHRs) in M33, NGC 6822 and M101. Comparison with previous determinations of emission-line fluxes shows large discrepancies; their probable origins are discussed. Combining our new photometric data with global velocity dispersion ( σ ) derived from emission linewidths, we review the     relation. A re-analysis of the properties of the GEHRs included in our sample shows that age spread and the superposition of components in multiple regions introduce a considerable spread in the regression. Combining the information available in the literature regarding ages of the associated clusters, evolutionary footprints on the interstellar medium, and kinematical properties of the knots that build up the multiple GEHRs, we find that a subsample – which we refer to as young and single GEHRs – do follow a tight relation in the     plane.  相似文献   

Unique first-forbidden β-decay rates for neutron-rich nickel isotopes in stellar environment     

Jameel-Un Nabi  Sabin Stoica 《Astrophysics and Space Science》2014,349(2):843-855

In astrophysical environments, allowed Gamow-Teller (GT) transitions are important, particularly for β-decay rates in presupernova evolution of massive stars, since they contribute to the fine-tuning of the lepton-to-baryon content of the stellar matter prior to and during the collapse of a heavy star. In environments where GT transitions are unfavored, first-forbidden transitions become important especially in medium heavy and heavy nuclei. Particularly in case of neutron-rich nuclei, first-forbidden transitions are favored primarily due to the phase-space amplification for these transitions. In this work the total β-decay half-lives and the unique first-forbidden (U1F) β-decay rates for a number of neutron-rich nickel isotopes, ^72–78Ni, are calculated using the proton-neutron quasi-particle random phase approximation (pn-QRPA) theory in stellar environment for the first time. For the calculation of the β-decay half-lives both allowed and unique first-forbidden transitions were considered. Comparison of the total half-lives is made with measurements and other theoretical calculations where it was found that the pn-QRPA results are in better agreement with experiments and at the same time are suggestive of inclusion of rank 0 and rank 1 operators in first-forbidden rates for still better results.  相似文献   

Kuramoto Model of Nonlinear Coupled Oscillators as a Way for Understanding Phase Synchronization: Application to Solar and Geomagnetic Indices     

Elena M. Blanter  Jean-Louis Le Mouël  Mikhail G. Shnirman  Vincent Courtillot 《Solar physics》2014,289(11):4309-4333

We apply a Kuramoto model of nonlinear coupled oscillators to the simulation of slow variations of the phase difference between sunspot number [R _I ] and geomagnetic indices [aa and ζ]. The Kuramoto model is described for the particular case of two oscillators connected by symmetric coupling with quasi-stationary behavior, and its properties are investigated. By solving an inverse problem, we reconstruct the evolution of the couplings between pairs of indices [R _I and aa, R _I and ζ, aa and ζ], and interpret these in terms of the physics of the solar dynamo. The de-correlation between R _I and geomagnetic indices found in Solar Cycle 20 by Le Mouël et al. (J. Geophys. Res. 117, A09103, 2012) is successfully reproduced by the Kuramoto model and corresponds to the alternation of the leading oscillator. Application of the Kuramoto model to the cross-correlations [C(R _I ,ζ) and C(aa,ζ)] for ζ-indices computed in eight geomagnetic stations shows the latitudinal dependence of the mean phase difference. We discuss these results in terms of the solar-wind contribution to local geomagnetic indices [ζ].  相似文献