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291.
Since 2013, round-the-clock monitoring of the sky has been carried out simultaneously in 96 beams using a high-sensitivity radio telescope called the Large Phased Array(LPA) at the frequency110.25 MHz. These observations are made under the program of interplanetary plasma investigation.The same data are used to search for pulsars by means of power spectra. To increase the sensitivity of the pulsar search, 500–600 power spectra corresponding to different days of observations are summed. In the integrated spectra of known pulsars, besides expected improvement in signal-to-noise(S/N) ratio for the frequency harmonics, some features are explored in this paper. We present the 27 strongest pulsars which are in a field with declination 21°-42°. The observable details in the integrated power spectra are connected with the presence of pulsar periods of the second(P_2) and third(P_3) class, which have been identified. Empirical relations for calculating these periods are obtained. The value P_2 is estimated for 26 pulsars, and for 15 sources it is made for the first time. The value P_3 is estimated for 13 pulsars,among them these values are given for five sources for the first time. 相似文献
292.
David Kaeter Martin A. Ziemann Ute Böttger Iris Weber Lutz Hecht Sergey A. Voropaev Alexander V. Korochantsev Andrey V. Kocherov 《Meteoritics & planetary science》2018,53(3):416-432
We present results of petrographic, mineralogical, and chemical investigations of three Chelyabinsk meteorite fragments. Three distinct lithologies were identified: light S3 LL5, dark S4–S5 LL5 material, and opaque fine-grained former impact melt. Olivine–spinel thermometry revealed an equilibration temperature of 703 ± 23 °C for the light lithology. All plagioclase seems to be secondary, showing neither shock-induced fractures nor sulfide-metal veinlets. Feldspathic glass can be observed showing features of extensive melting and, in the dark lithology, as maskelynite, lacking melt features and retaining grain boundaries of former plagioclase. Olivine of the dark lithology shows planar deformation features. Impact melt is dominated by Mg-rich olivine and resembles whole-rock melt. Melt veins (<2 mm) are connected to narrower veinlets. Melt vein textures are similar to pegmatite textures showing chilled margins, a zone of inward-grown elongated crystals and central vugs, suggesting crystallization from supercooled melt. Sulfide-metal droplets indicate liquid immiscibility of both silicate and sulfide as well as sulfide and metal melts. Impact melting may have been an important factor for differentiation of primitive planetary bodies. Graphite associated with micrometer-sized melt inclusions in primary olivine was detected by Raman mapping. Carbon isotopic studies of graphite could be applied to test a possible presolar origin. 相似文献
293.
The southward near-surface transport of transformed subarctic water across the Subpolar Front in the Japan Sea is simulated and analyzed based on altimeter data from January 1, 1993 to December 31, 2017. Computing Lagrangian indicators for a large number of synthetic particles, advected by the AVISO velocity field, we find preferred transport pathways across the Subpolar Front. The southward transport occurs mainly in the central part of the frontal zone due to suitable dispositions of mesoscale eddies promoting propagation of subarctic water to the south. It is documented with the help of Lagrangian origin and L-maps and verified by the tracks of available drifters. The transport of transformed subarctic water to the south is compared with the transport of transformed subtropical water to the north simulated by Prants et al. (Nonlinear Process Geophys 24(1):89–99, 2017c). 相似文献
294.
Non‐hyperbolic generalised moveout approximation is a powerful tool to approximate the travel‐time function by using information obtained from two rays. The standard approach for parameter selection is using three parameters defined from zero‐offset ray and two parameters obtained from a reference ray. These parameters include the travel time and travel‐time derivatives of different order. The original parameter selection implies more fit at zero offset compared with offset from a reference ray. We propose an alternative approach for parameter selection within the frame of generalised moveout approximation by transferring more fit from the zero offset to a reference ray by changing in parameter selection. The modified approximation is tested against the original one in few analytical model examples, including the multi‐layered model. 相似文献
295.
Daniel Karthe Sergey Chalov Vsevolod Moreido Margarita Pashkina Anna Romanchenko Gunsmaa Batbayar Andrei Kalugin Katja Westphal Marcus Malsy Martina Flörke 《Water Resources》2017,44(3):399-416
The Selenga River is the main artery feeding Lake Baikal. It has a catchment of ~450000 km² in the boundary region between Northern Mongolia and Southern Siberia. Climate, land use and dynamic socioeconomic changes go along with rising water abstractions and contaminant loads originating from mining sites and urban wastewater. In the future, these pressures might have negative impacts on the ecosystems of Lake Baikal and the Selenga River Delta, which is an important wetland region in itself and forms the last geobiochemical barrier before the Selenga drains into Lake Baikal. The following study aims to assess current trends in hydrology and water quality in the Selenga-Baikal basin, identify their drivers and to set up models (WaterGAP3 framework and ECOMAG) for the prediction of future changes. Of particular relevance for hydrological and water quality changes in the recent past were climate and land use trends as well as contaminant influx from mining areas and urban settlements. In the near future, additional hydrological modifications due to the construction of dams and abstractions/water diversions from the Selenga’s Mongolian tributaries could lead to additional alterations. 相似文献
296.
Motorina G. G. Lysenko A. L. Anfinogentov S. A. Fleishman G. D. 《Geomagnetism and Aeronomy》2020,60(7):929-935
Geomagnetism and Aeronomy - Quite often powerful flares occur during a decrease of solar activity. In this work, we make an attempt to consider X-class flares at the minima of solar activity cycles... 相似文献
297.
SLOBODSKOVA Valentina V. ZHURAVEL Elena V. KUKLA Sergey P. CHELOMIN Victor P. 《中国海洋大学学报(英文版)》2019,(1):159-164
Marine pollution affects all life processes in aquatic organisms. The genotoxic effect of pollution on the mussel Crenomytilus grayanus was assessed. Bivalves were collected from the ‘clean'(Vostochnaya Cove) and polluted(Nakhodka Bay) areas in the Peter the Great Bay. The degree of DNA damage in C. grayanus was determined by alkaline comet assay as mean percentage of DNA in tail, and the genetic damage index was calculated. Our results indicate that almost one-third of DNA in cells of gills and digestive gland of C. grayanus inhabiting the Nakhodka Bay had destructive changes compared to the individuals of this species from the Vostochnaya Cove. This study has shown that chronic pollution of the aquatic environment causes destructive changes to DNA in gill and digestive gland cells of C. grayanus. 相似文献
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300.
Ocean Dynamics - Long-lived and large-scale anticyclonic Aleutian eddies (AEs), detaching from the Alaskan Stream to the west of 180∘ and propagating southwestward or almost zonally in the... 相似文献