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281.
We study the dynamics of extended shells of relatively low-mass particles around and inside the orbit of two heavy centres of gravity (a binary) by computer simulations. The binary components are surrounded byN = 16 000 small mass particles in uniform random distribution on few spherical envelopes with different radii expanding with respective velocities. Some shells are inside the orbit of binary.We apply this model to binary galaxy systems with baryonic dark matter, e.g., massive black holes. In principle, we can apply this model to different kinds of objects (from binary star systems until superclusters of galaxies).It is shown that the shell expands homologously with a decreasing velocity and then, falls back into the binary system forming zones of compressed matter. At some moment of time there could be a collapse of these particles on to the heavier component of the binary. Further in time, some part of particles which were outside the binary orbit escape from the system. Other particles which were initially inside of the orbit are captured by binary components.We consider a number of different models with different initial parameters. For models with smaller radii of shells, about one-half of the particles escape from systems; whereas for larger values the shell disrupts as a whole. Escaping particles form collimated flows in planes of orbits of binaries. Positions of flows and directions of motion depend on positions of heavier components of binaries at the moment of a closest approach of particles and on ratios of masses of binary components.We show that during evolution of our models different kinds of structures of systems often are very similar to the observed structures of galaxies: spiral and elliptical galaxies, interacting galaxies, different kinds of flows and jets. Totally systems are expanding - after 40 periods of rotation of the binary the system expands by 300 times.  相似文献   
282.
The aim of the present paper is to analyze the light variation as well as the period changes of the eclipsing binary RZ Cas. New photometric elements are computed using the frequency-domain method. The possibility of the light-time effect and the apsidal motion is discussed.  相似文献   
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Systematic mapping of a transect along the well-exposed shores of Georgian Bay, Ontario, combined with the preliminary results of structural analysis, geochronology and metamorphic petrology, places some constraints on the geological setting of high-grade metamorphism in this part of the Central Gneiss Belt. Correlations within and between map units (gneiss associations) have allowed us to recognize five tectonic units that differ in various aspects of their lithology, metamorphic and plutonic history, and structural style. The lowest unit, which forms the footwall to a regional decollement, locally preserves relic pre-Grenvillian granulite facies assemblages reworked under amphibolite facies conditions during the Grenvillian orogeny. Tectonic units above the decollement apparently lack the early granulite facies metamorphism; out-of-sequence thrusting in the south produced a duplex-like structure. Two distinct stages of Grenvillian metamorphism are apparent. The earlier stage (c. 1160–1120 Ma) produced granulite facies assemblages in the Parry Sound domain and upper amphibolite facies assemblages in the Parry Island thrust sheet. The later stage (c. 1040–1020 Ma) involved widespread, dominantly upper amphibolite facies metamorphism within and beneath the duplex. Deformation and metamorphism recently reported from south and east of the Parry Sound domain at c. 1100–1040 Ma have not yet been documented along the Georgian Bay transect. The data suggest that early convergence was followed by a period of crustal thickening in the orogenic core south-east of the transect area, with further advance to the north-west during and after the waning stages of this deformation.  相似文献   
285.
Globorotalia puncticulata and Globorotalia margaritae are critical species that define internationally recognized planktonic foraminiferal biozones in the Pliocene. These biozones are defined from stratotype sections on Sicily and their fauna are commonly considered to have been introduced to the Mediterranean after an influx of Atlantic water that terminated the late Miocene desiccation of the basin. Herein new discoveries of these species in rocks that predate the late Miocene desiccation are described. These data are supported by magneto- and lithostratigraphy that have been integrated at a single continuous section. Not only do these discoveries question the existing foraminiferal biozone stratigraphy, they also suggest new models for the dispersal of planktonic species. It is proposed that Globorotalia puncticulata and perhaps even Globorotalia margaritae evolved in the Mediterranean during earliest Messinian times (during or before chron C3Bn1n) and dispersed into the Atlantic. This suggests that a marine connection remained between the two sea areas until at least chron C3An.1n. Using the existing geomagnetic polarity time scale, these occurrences are some 2 Myr earlier than previously recorded in the Mediterranean. The distribution of G. margaritae and G. puncticulata in Mediterranean sections is likely to reflect palaeoenvironment or the preservation of deposits rather than the absolute age of the sediments.  相似文献   
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288.
The boehaviour and ultimate effect and fate of oil in the marine environment in the polar region depend on a large number of factors. From a chemical point of view the most important ones to consider are the intrinsic chemical properties of the oil, the consequences of oil/water interactions, the influence of ice on physical and chemical processes, and the interactions between oil and light when the influx of solar energy shows great seasonal changes. This paper reviews the main aspects of these issues.  相似文献   
289.
Oil-weathering processes in ice-free subarctic and Arctic waters include spreading, evaporation, dissolution, dispersion of whole-oil droplets into the water column, photochemical oxidation, water-in-oil emulsification, microbial degradation, adsorption onto suspended particulate material, ingestion by organisms, sinking, and sedimentation. While many of these processes also are important factors in ice-covered waters, the various forms of sea ice (depending on the active state of ice growth, extent of coverage and/or decay) impart drastic, if not controlling, changes to the rates and relative importance of different oil-weathering mechanisms. Flow-through seawater wave-tank experiments in a cold room at −35°C and studies in the Chukchi Sea in late winter provide data on oil fate and effects for a variety of potential oil spill scenarios in the Arctic. Time-series chemical weathering data are presented for Prudhoe Bay crude oil released under and encapsulated in growing first-year columnar ice through spring breakup.  相似文献   
290.
I.IN~crIOXLocatedinthecoddlepatofTallmBasin,withanareaof33.76X104klnZ,theTaldirnakan~isinthehinterlandofEurasia.Blockedbythehighmountainsaround,vapourofoceancanhardlyreachthedesert.APartfromthis,asthedeSertisinthesinkingcompensationareaoftheascensionalaircurrentaamstheQinghal-XIZangPlateau,itSprecipitationisrareandtheevaporationcapacityisintensealltheyearround.Allthesecontributetotheformationsofthetypifydrydesertclimate.Theacidityindexofthedesertandthearoundregionisashighasmorethan50,w…  相似文献   
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