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81.
The problem of influence of the ambiental intergalactic pressure on extended gas associated with normal field galaxies is briefly discussed. An empirically established characteristic radius of absorption can not be explained in the context of simple two-phase halo model as a consequence of pressure equilibrium of the hot halo with the smooth intergalactic medium. This conclusion is based upon the stringent constraints on the temperature and density of the intergalactic plasma obtained through the CMBR measurements. On the other hand, ram-pressure stripping caused by peculiar motions of galaxies does present a viable alternative for the hot halo truncation. It is shown that for a particular set of chosen parameters, a simple model is capable of producing the absolute upper limit on the extent of gas associated with the galaxy. The values obtained are compatible with the results of the recent QSO absorption-line studies, and are significantly higher than the radius at which the cooling timescale of the halo gas equates the dynamical timescale. 相似文献
82.
Oxana V. Lunina Andrei S. Gladkov Igor S. Novikov Anna R. Agatova Evgenii M. Vysotskii Alexei A. Emanov 《Tectonophysics》2008,453(1-4):276
The co-seismic deformations produced during the September 27, 2003 Chuya earthquake (Ms = 7.5) that affected the Gorny Altai, Russia, are described and discussed along a 30 km long segment. The co-seismic deformations have manifested themselves both in unconsolidated sediments as R- and R′-shears, extension fractures and contraction structures, and in bedrock as the reactivation of preexisting schistosity zones and individual fractures, as well as development of new ruptures and coarse crushing zones. It has been established that the pattern of earthquake ruptures represents a typical fault zone trending NW–SE with a width reaching 4–5 km and a dextral strike–slip kinematics. The initial stress field that produced the whole structural pattern of co-seismic deformations during the Chuya earthquake, is associated with a transcurrent regime with a NNW–SSE, almost N–S, trending of compressional stress axis (σ1), and a ENE–WSW, almost E–W, trending of tensional stress axis (σ3). The state of stress in the newly-formed fault zone is relatively uniform. The local stress variations are expressed in insignificant deviation of σ1 from N–S to NW–SE or NE–SW, in short-term fluctuations of relative stress values in keeping their spatial orientations, or in a local increase of the plunge angle of the σ1. The geometry of the fault zone associated with the Chuya earthquake has been compared with the mechanical model of fracturing in large continental fault zones with dextral strike–slip kinematics. It is apparent that the observed fracture pattern corresponds to the late disjunctive stage of faulting when the master fault is not fully developed but its segments are already clearly defined. It has been shown that fracturing in widely different rocks follows the common laws of the deformation of solid bodies, even close to the Earth surface, and with high rates of movements. 相似文献
83.
Perelet Alexei O. Ward Helen C. Stoll Rob Mahaffee Walter F. Pardyjak Eric R. 《Boundary-Layer Meteorology》2022,184(3):479-504
Boundary-Layer Meteorology - Scintillometry is a non-invasive measurement technique for acquiring spatially-averaged surface heat and moisture fluxes in areas where setting up arrays of instruments... 相似文献
84.
Alexei Gvishiani Renata Lukianova Anatoly Soloviev Andrei Khokhlov 《Surveys in Geophysics》2014,35(5):1123-1154
An overview of the geomagnetic observations made in the northern part of Russia is presented from a historical perspective. Several stations were deployed on the territory of the former Soviet Union during the International Geophysical Year, 1957–1958, with the active participation and guidance of the Interagency Geophysical Committee which is inherited by the Geophysical Center of the Russian Academy of Sciences (GC RAS). In the 1990s, the majority of these stations, especially those in the remoter regions, were closed. Nowadays, the geomagnetic network, including the observatories of the INTERMAGNET program, has been restored. Examples of high-latitude geomagnetic variations in the Russian longitudinal sector are shown, and maps and trends of the secular variation over the territory of Russia presented. Particular attention is paid to the automated processing of data and to the analysis methods used. To process the growing amount of high-resolution geomagnetic data, sophisticated mathematical methods based on the fuzzy logic approach and new discrete mathematical analysis algorithms have been developed. The formal methods and algorithms for recognizing both artificial and natural disturbances in the magnetograms are described. 相似文献
85.
Y/Ho Ratios in the Late Cenozoic Basalts from the Eastern Tuva, Russia: An ICP-MS Study with Enhanced Data Quality 总被引:1,自引:0,他引:1
Alexei V. Ivanov Sergei V. Rasskazov Evgeny P. Chebykin Margarita E. Markova Elena V. Saranina 《Geostandards and Geoanalytical Research》2000,24(2):197-204
A set of forty seven Late Cenozoic basaltic rocks from the Eastern Tuva (southern Siberia, Russia) have been studied by ICP-MS using In as an internal standard. Yttrium and Ho concentrations, determined along with other trace elements, varied systematically from one analytical run to another and covered the entire charge-and-radius-controlled field within the range 24 < Y/Ho < 34, so obscuring any geochemical interpretation. A correction procedure was therefore developed in which the Y/Ho ratios were recalculated using concentrations of these elements determined in international and in-house reference materials (BHVO-1, AGV-1, BIR-1 and U-94-5). Statistical analysis of the recalculated data set revealed two groups of samples not related by their genesis but rather by their respective analytical runs. Fourteen samples originally analysed in five different runs were then re-measured by the same instrument in peak-hopping mode using only specific mass peaks (m/z = 89, 115 and 165). All of these samples yielded Y/Ho ratios in a narrow range between 29 and 31, thus illustrating how analytical problems in the determination of Y and Ho by routine ICP-MS procedures can be overcome. Finally, a mean value of Y/Ho = 30.3 ± 1.1 (1s) was derived for the basaltic rocks of the Eastern Tuva. This is close to the value of 28.8 accepted for chondrites and for ocean island basalts. Despite the uniform Y/Ho ratio, the element concentrations in basaltic rocks from the Eastern Tuva show systematic enrichment in heavy rare earth elements and yttrium from the Miocene to the Quaternary. 相似文献
86.
Observations of the strength and spatial distribution of vector magnetic fields in active regions have revealed several fundamental
properties of the twist of their magnetic fields. First, the handedness of this twist obeys a hemispheric rule: left-handed
in the northern hemisphere, right-handed in the southern. Second, the rule is weak; active regions often disobey it. It is
statistically valid only in a large ensemble. Third, the rule itself, and the amplitude of the scatter about the rule, are
quantitatively consistent with twisting of fields by turbulence as flux tubes buoy up through the convection zone. Fourth,
there is considerable spatial variation of twist within active regions. However, relaxation to a linear force-free state,
which has been documented amply in laboratory plasmas, is not observed. 相似文献
87.
Aleksandrina Smirnova Alexei Moiseev 《Monthly notices of the Royal Astronomical Society》2010,401(1):307-318
We are presenting new results on kinematics and structure of the Mrk 334 Seyfert galaxy. Panoramic (3D) spectroscopy is performed at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences using the integral-field Multi-Pupil Fiber Spectrograph (MPFS) and scanning Fabry–Pérot interferometer. The deep images have revealed that Mrk 334 is observed during the final stage of its merging with a massive companion. A possible mass ratio ranges from 1/5 to 1/3. The merger has triggered mass redistribution in the disc resulting in an intensification of nuclear activity and in a burst of star formation in the inner region of the galaxy. The circumnuclear starburst is so intense that its contribution to the gas ionization exceeds that contribution of the active galactic nuclei (AGN). We interpret the nuclear gas outflow with velocities of ∼200 km s−1 as a galactic superwind that accompanies the violent star formation. This suggestion is consistent with the asymmetric X-ray brightness distribution in Mrk 334. The trajectory of the fragments of the disrupted satellite in the vicinity of the main galaxy nucleus can be traced. In the galaxy disc, a cavern is found that is filled with a low-density ionized gas. We consider this region to be the place where the remnants of the companion have recently penetrated through the gaseous disc of the main galaxy. 相似文献
88.
A multifunctional HTDMA system with a robust temperature control 总被引:3,自引:0,他引:3
The hygroscopicity of atmospheric aerosols significantly influences their size distribution,
cloud condensation nuclei ability, atmospheric residence time, and climate forcing. In order to investigate
the hygroscopic behavior of aerosol particles and serious haze in China, a Hygroscopic Tandem Differential
Mobility Analyzers (HTDMA) system was designed and constructed at Fudan University. It can function as a
scanning mobility particle sizing system to measure particle size distribution in the range of 20--1000 nm
in diameter, as well as a hygroscopicity analyzer for aerosol particles with diameters between 20--400 nm
in the range of 20%--90% RH (relative humidity). It can also measure the effect of uptake of inorganic acids
or semi-VOCs on the hygroscopic behavior of aerosols, such as typical inorganic salts in atmospheric dust or
their mixtures. The performance tests show that the system measured particle size of the standard polystyrene
latex spheres (PSLs) is 197 nm, which is in excellent agreement with the certified diameter D=199±6 nm, as
well as a standard deviation of the repeated runs SD=8.9x10-4. In addition, the measured hygroscopic
growth factors of the model compounds, (NH4)2SO4 and NaNO3, agree with the Kohler theoretical
curves. The results indicate that the HTDMA system is an excellent and powerful tool for studying the
hygroscopic behavior of submicron aerosols and meets the demand required for laboratory research and
fieldwork on atmospheric aerosols in China. 相似文献
89.
Burgess RM Konovets IM Kipnis LS Lyashenko AV Grintsov VA Petrov AN Terletskaya AV Milyukin MV Povolotskii MI Demchenko VY Bogoslovskaya TA Topkin YV Vorobyova TV Portis LM Ho KT 《Marine pollution bulletin》2011,62(11):2442-2462
During the Soviet era, Ukraine was an important industrial and agricultural region of the Soviet Union. This industrial and agricultural activity resulted in contamination of Ukraine’s estuaries with legacy anthropogenic pollutants. Investigations on the toxicological effects of this estuarine contamination have been limited. For this research, we measured the toxicity of contaminated sediments from four Ukrainian estuaries to several aquatic organisms over 3 years. Sediment chemical analyses and whole sediment toxicity identification evaluations (TIEs) were also performed to determine the classes of contaminants contributing to toxicity. Toxic sediments were observed in several of the Ukrainian estuaries and chemical analyses of the sediments demonstrated anthropogenic contaminants were widely distributed. Contaminants were also detected in macrobenthic organisms collected from the sediments. Several lines of evidence, including TIEs, indicated hydrophobic organic chemicals (HOCs) were contributing substantially to observed toxicity. This information can guide environmental managers to prioritize portions of the estuaries requiring remediation. 相似文献
90.
Loris Foresti Devis Tuia Mikhail Kanevski Alexei Pozdnoukhov 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(1):51-66
This paper presents multiple kernel learning (MKL) regression as an exploratory spatial data analysis and modelling tool.
The MKL approach is introduced as an extension of support vector regression, where MKL uses dedicated kernels to divide a
given task into sub-problems and to treat them separately in an effective way. It provides better interpretability to non-linear
robust kernel regression at the cost of a more complex numerical optimization. In particular, we investigate the use of MKL
as a tool that allows us to avoid using ad-hoc topographic indices as covariables in statistical models in complex terrains.
Instead, MKL learns these relationships from the data in a non-parametric fashion. A study on data simulated from real terrain
features confirms the ability of MKL to enhance the interpretability of data-driven models and to aid feature selection without
degrading predictive performances. Here we examine the stability of the MKL algorithm with respect to the number of training
data samples and to the presence of noise. The results of a real case study are also presented, where MKL is able to exploit
a large set of terrain features computed at multiple spatial scales, when predicting mean wind speed in an Alpine region. 相似文献