From Big to Little Rip in modified F(R,G) gravity     

Andrey N. Makarenko  Valery V. Obukhov  Iliy V. Kirnos 《Astrophysics and Space Science》2013,343(1):481-488

We discuss the cosmological reconstruction in modified Gauss-Bonnet (GB) gravity. It is demonstrated that the modified GB gravity may describe the most interesting features of late-time cosmology. We derive explicit form of effective phantom cosmological models ending by the finite-time future singularity (Big Rip) and without singularities in the future (Little Rip).  相似文献   

Measurements of the ionosphere plasma electron density variation by the Kharkov incoherent scatter radar     

Iurii V. Cherniak  Valery N. Lysenko 《Acta Geophysica》2013,61(5):1289-1303

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Middle-Upper Miocene stratigraphy of the Taman Peninsula, Eastern Paratethys     

Eleonora P. Radionova  Larisa A. Golovina  Natalia Yu. Filippova  Valery M. Trubikhin  Sergey V. Popov  Irina A. Goncharova  Yulia V. Vernigorova  Tatiana N. Pinchuk 《Central European Journal of Geosciences》2012,4(1):188-204

The stratigraphy of the Taman Peninsula is defined using the sections at Zelensky Hill ?? Panagia, Popov Kamen, Taman and Zheleznyi Rog. The stratigraphy is constructed from distribution of mollusks, foraminifers, nannofossils, diatoms, and organic-walled phytoplankton, as well as incorporating paleomagnetic data. The occurrence of oceanic diatom species in the Middle-Upper Sarmatian, Maeotian and Lower Pontian makes a direct correlation possible between the sections studied, the Mediterranean basin and oceanic zonation. The new data on planktonic and benthic biotic groups suggests a pulsating connection of the Eastern Paratethys with the open marine basins, especially during transitional intervals within constant environments. Comprehensive studies of the Chokrakian-Kimmerian microbiota provide evidence for several levels of marine microbiotic associations that are related to short-term marine invasions. The biotic and paleomagnetic data of the Taman Peninsula sections give a more comprehensive, but sometimes a controversial picture on the Eastern Paratethys history and the nature of its relationship with the adjacent marine basins.  相似文献   

Flux-Gate Magnetometers Design Peculiarities     

Valery Korepanov  Andriy Marusenkov 《Surveys in Geophysics》2012,33(5):1059-1079

The most widespread instrument used today for the measurement of quasi-stationary and slowly fluctuating vector magnetic fields is a flux-gate magnetometer (FGM). The most important parameter characterizing the magnetometer quality is its magnetic noise—its threshold sensitivity or its own noise level (NL). Based on the results of experimental research, we may state that the FGM NL mainly depends on the quality of the magnetic material used for FGM sensor core. The “solid liquid” model explaining the nature of magnetic noise is proposed and substantiated. It is demonstrated that special attention has to be paid to the annealing of the core. A new effect—termed gamma-magnetic normalization—is discovered and discussed. It is shown that the magnetometer NL depends not only on the core length and volume but also on the excitation mode of the core. Besides, the ways to improve other factors, such as power consumption and thermal drift which must be taken into account in order to create a FGM with the highest possible performance, are discussed. Some examples are given of the parameters of present advanced FGMs for geophysical uses.  相似文献   

Propagating PZ 90 to WGS 84 Transformation Parameters     

Yuri A. Bazlov  Viktor F. Galazin  Boris L. Kaplan  Valery G. Maksimov  Vladimir P. Rogozin 《GPS Solutions》1999,3(1):13-16

The 29^th Research Institute recently published its latest transformation parameters for WGS and PZ 90. Because these tranformation parameter estimates were derived from stations located within Russia, variance-covariance propagation was carried out to study the benefits of a better global distribution of stations. An example that includes two stations in North America is presented. The transformation improves significantly. ? 1999 John Wiley & Sons, Inc.  相似文献   

Spatial dealiasing of 3-D seismic reflection data     

Shuki Ronen  Valery Sorin  Richard Bale 《Geophysical Journal International》1991,105(2):503-511

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The comparable analysis of the Cepheids and non-variable supergiants from the instability strip.I     

Sergei M. Andrievsky  Valery V. Kovtyukh 《Astrophysics and Space Science》1996,245(1):61-80

The elemental abundances, temperatures, gravities and microturbulence velocities were derived for 14 non-variable supergiants from the Cepheids' instability strip and two hotter supergiants. For 8 stars the abundances were determined for the first time. The comparable analysis of the program stars' chemical composition and that of the small-amplitude Cepheids has shown that there is no essential differences in the elemental abundances for two stellar groups. Some discussion of the phenomenon of non-variable supergiants in the instability strip is given.  相似文献   

Gas Chromatographic Determination of Extractable Compounds Composition and Emission Rate of Volatile Terpenes from Larch Needle Litter     

Valery?IsidorovEmail author  Vera?Vinogorova  Krzysztof?Rafa?owski 《Journal of Atmospheric Chemistry》2005,50(3):263-278

A combination of solid-phase microextraction (SPME) and gas chromatography can be successfully used both for establishing the qualitative composition of volatile organic compounds (VOC) emitted by leaf litter and for determining their emission rates. Taking as an example European larch litter, it is shown that dead plant material contains considerable amounts of volatile components as well as non-volatile compounds that can be VOC precursors formed as a result of enzymatic reactions. It is proposed to include the determination of extractable compounds into the methodology of studying litter as a source of atmospheric VOC. Some data on litter mass are reported and it is concluded that this data may be included into special models for emission evaluation. In this work the distribution coefficients of monoterpene hydrocarbons between the gas phase and polydimethylsiloxane fiber coating necessary for quantitative determinations in SPME were estimated.  相似文献   

Light propagation in a universe with spatial inhomogeneities     

Victor?LamburtEmail author  Dmitry?Sokoloff  Valery?Tutubalin 《Astrophysics and Space Science》2005,298(3):409-418

A light propagation in a universe which is homogeneous only in average systematically differs from a light propagation in a strictly homogeneous Universe. We demonstrate a link between this effect and the general theory of transport phenomenon in random media. The effective spatial curvature of a universe which is homogeneous only in average is introduced. This curvature is governing a light propagation in such universe. We show that the effective spatial curvature is lower than the average curvature. It implies that a universe with critical mean density looks like a space with negative curvature.  相似文献   

The relative importance of water and diet for uptake and subcellular distribution of cadmium in the deposit-feeding polychaete, Capitella sp. I     

Selck H  Forbes VE 《Marine environmental research》2004,57(4):261-279

The impact of dietary and water exposure on the accumulation and distribution of cadmium (Cd) in subcellular components of the polychaete Capitella sp. I was investigated. Worms were exposed to either dissolved Cd alone ('Water-Only' treatments; WO) or diet-bound Cd alone ('Algae-bound Only' treatments; AO). Thus, WO worms were starved and AO worms were fed. Differential centrifugation was used to fractionate worm homogenates into debris- (DE), mitochondrial- (MI), microsomal- (MC) and cytosolic- (CY) fractions, and the concentration of Cd in these fractions was quantified by radiometric analysis using the specific activity of the (109)Cd radioisotope. Neither exposure route nor Cd exposure affected the total protein content in the worms. However, fed, but not starved worms relocated proteins from the mitochondria to the cytosol in response to Cd exposure. In systems without Cd addition, starvation likewise influenced the distribution of protein between mitochondria and cytosol. Cutaneous uptake and accumulation of Cd from the water was related to surface area while dietary uptake was influenced by the amount of sediment passing through the gut. Irrespective of exposure route, Cd was accumulated primarily in the debris fraction although comparisons between the treatments indicated that relatively less Cd was located in DE and more in MI, MC and CY fractions in worms in AO compared to worms in WO. Cd per unit protein in DE and MI fractions was twice as high as in MC and CY fractions in WO, whereas MC contained the highest Cd content followed by MI, DE and CY fractions in AO worms. Our results stress the importance of exposure route for the internal distribution and toxicity of Cd to deposit feeders such as Capitella sp. I.  相似文献