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481.
Oleg?MalkovEmail author Aleksej?Mironov Sergej?Sichevskij 《Astrophysics and Space Science》2011,335(1):105-111
Detection of a composite flux in photometry can serve as an indication of a photometrically unresolved binarity and can contribute
to the parameterization of the components of binary systems. A main goal of the present study is to develop a method of automatic
photometric detection of binaries, based on multi-color photometry, theoretical stellar spectral energy distributions and
general understanding of binary evolution. In particular, we consider an ultraviolet photometry where, in combination with
optical and infrared photometry, interstellar reddening can be easier distinguished from temperature reddening. 相似文献
482.
We present a statistical study of the characteristics of type-II radio bursts observed in the metric (m) and deca-hectometer
(DH) wavelength range during 1997–2008. The collected events are divided into two groups: Group I contains the events of m-type-II
bursts with starting frequency ≥ 100 MHz, and group II contains the events with starting frequency of m-type-II radio bursts
< 100 MHz. We have analyzed both samples considering three different aspects: i) statistical properties of type-II bursts, ii) statistical properties of flares and CMEs associated with type-II bursts, and iii) time delays between type-II bursts, flares, and CMEs. We find significant differences in the properties of m-type-II bursts
in duration, bandwidth, drift rate, shock speed and delay between m- and DH-type-II bursts. From the timing analysis we found
that the majority of m-type-II bursts in both groups occur during the flare impulsive phase. On the other hand, the DH-type-II
bursts in both groups occur during the decaying phase of the associated flares. Almost all m-DH-type-II bursts are found to
be associated with CMEs. Our results indicate that there are two kinds of shock in which group I (high frequency) m-type-II
bursts seem to be ignited by flares whereas group II (low frequency) m-type-II bursts are CME-driven. 相似文献
483.
In understanding the nucleosynthesis of the elements in stars, one of the most important quantities is the reaction rate and
it must be evaluated in terms of the stellar temperature T, and its determination involves the knowledge of the excitation function σ(E) of the specific nuclear reaction leading to the final nucleus. In this paper, the effect of thermonuclear reaction rates
to the pre-main sequence evolution of low mass stars having masses 0.7, 0.8, 0.9 and 1M⊙ are studied by using our modified Stellar Evolutionary Program. 相似文献
484.
Zdeněk ?vestka 《Solar physics》2010,267(2):235-250
I recount my career in solar physics beginning at Ondřejov Observatory in 1948 and ending with my ∼30 year stay at the Laboratory
of Space Research in Utrecht. 相似文献
485.
High-pressure granulite from Western Kunlun,northwestern China: Its metamorphic evolution,zircon SHRIMP U-Pb ages and tectonic implication 总被引:1,自引:0,他引:1
QU JunFeng ZHANG LiFei AI YongLiang L Zeng WANG JianPing ZHOU Hui & WANG ShiYan MOE Key Laboratory of Orogenic Belts Crustal Evolution School of Earth Space Science Peking University Beijing China Henan Polytechnic University Jiaozuo China Geological Survey of Henan Province Zhengzhou China 《中国科学D辑(英文版)》2007,50(7):961-971
High-pressure mafic granulites occurring as lenticular bodies within garnet-amphibolites in Kangxiwar Fault have been first reported in this paper. The P-T conditions of two metamorphic stages were ob-tained using calibrated geothermal barometers and ThermoCalc Program. The peak metamorphic con-dition of these high-pressure granulites is about 760―820℃,1.0―1.2 GPa and the retrograde meta-morphic condition is about 620―720℃,0.7―0.8 GPa. The petrological studies show that they have a near-isobaric cooling P-T... 相似文献
486.
In this article, an approach for the efficient numerical solution of multi-species reactive transport problems in porous media
is described. The objective of this approach is to reformulate the given system of partial and ordinary differential equations
(PDEs, ODEs) and algebraic equations (AEs), describing local equilibrium, in such a way that the couplings and nonlinearities
are concentrated in a rather small number of equations, leading to the decoupling of some linear partial differential equations
from the nonlinear system. Thus, the system is handled in the spirit of a global implicit approach (one step method) avoiding
operator splitting techniques, solved by Newton’s method as the basic algorithmic ingredient. The reduction of the problem
size helps to limit the large computational costs of numerical simulations of such problems. If the model contains equilibrium
precipitation-dissolution reactions of minerals, then these are considered as complementarity conditions and rewritten as
semismooth equations, and the whole nonlinear system is solved by the semismooth Newton method. 相似文献
487.
Hayfaa Abdul Aziz Madelaine B?hme Alexander Rocholl Jerome Prieto Jan R. Wijbrans Valerian Bachtadse Albert Ulbig 《International Journal of Earth Sciences》2010,99(8):1859-1886
A detailed integrated stratigraphic study (biostratigraphy and magnetostratigraphy) was carried out on five sections from
the western part of the Bavarian Upper Freshwater Molasse of the North Alpine Foreland Basin (NAFB), greatly improving the
chronostratigraphy of these sediments. The sections belong to the lithostratigraphic units Limnische Untere Serie (UL) and Fluviatile Untere Serie (UF) and contain 19 (mostly new) small-mammal bearing levels, significantly refining the local biostratigraphy. Radiometric
ages obtained from glass shards from tuff horizons are used together with the biostratigraphic information for constructing
and confirming the magnetostratigraphic correlation of the studied sections to the Astronomical Tuned Time Scale (ANTS04;
Lourens et al. in Geologic Time Scale 2004, Cambridge University Press, 2004). This correlation implies that the UL lithostratigraphic
unit corresponds to the latest Ottnangian and the Early Karpatian, whereas the UF corresponds to the Karpatian and the Early
Badenian. This indicates that the Brackish- to Freshwater Molasse transition already occurred during the late Ottnangian.
The pre-Riesian hiatus occurred in the latest Karpatian and lower Early Badenian in Eastern Bavaria and Bohemia and in the
Late Karpatian and earliest Badenian in Western Bavaria. The geochemical and Ar–Ar data of volcanic ashes suggest that highly
evolved silicic magmas from a single volcano or volcanic center, characterized by a uniform Nd isotopic composition, erupted
repetitively over the course of at least 1.6 Myr. Three phases of eruptive activity were identified at 16.1 ± 0.2 Ma (Zahling-2),
15.6 ± 0.4 Ma (Krumbad), and 14.5 ± 0.2 Ma (Heilsberg, Hegau). The correlation of the local biostratigraphic zonation to the
ANTS04 enables further the characterization of both the Ottnangian–Karpatian and Karpatian–Badenian boundaries in the NAFB
by small-mammal biostratigraphy. According to these results the Ottnangian–Karpatian boundary is contemporaneous with the
first appearance datum of Megacricetodon
bavaricus (in the size of the type population) and the first common occurrence of Keramidomys thaleri, whereas Ligerimys florancei, Melissiodon dominans and Prodeinotherium aff. bavaricum have been already disappeared during the late Ottnangian. The Karpatian–Badenian boundary is characterized by a significant
size increase of the large Megacricetodon lineage and possibly a (re-)immigration of Prodeinotherium bavaricum. 相似文献
488.
A compilation of phytoplankton species abundance data from the spring bloom along the northern Norwegian coast and in the
Barents Sea shows that the quantitatively most important species are the prymnesiophyte Phaeocystis pouchetii and the common cold water to temperate diatoms Chaetoceros socialis, Skeletonema costatum sensu lato, Fragilariopsis oceanica, Thalassiosira spp., Chaetoceros furcellatus, Chaetoceros compressus, Chaetoceros debilis and Bacterosira bathyomphala. The relative abundance of diatoms and Phaeocystis varied highly and apparently stochastically between years. P. pouchetii occurred during all stages of the spring bloom and sometimes completely dominated the phytoplankton community. Along the
Norwegian coast, the importance of P. pouchetii increased northwards. The species composition in coastal fjords at 70° N is surprisingly similar to that of shelf waters
in the Barents Sea (up to 80° N). An exception is S. costatum sensu lato which was seldom observed in Arctic waters. Small flagellates (<10 μm) other than dinoflagellates and P. pouchetii are also important among the Barents Sea spring phytoplankton. Associations of species seem rigid over time and are dominated
by C. socialis and P. pouchetii in northern waters. Biogeographical categories of spring bloom species in relation to environmental conditions are discussed. 相似文献
489.
Clarisse Odebrecht Marli Bergesch Leonardo Rubi R?rig Paulo C. Abreu 《Estuaries and Coasts》2010,33(2):570-583
A long-term study (monthly sampling, 1992 to 2007) was conducted in the surf zone of Cassino Beach, Southern Brazil, in order
to detect possible natural and/or anthropogenic disturbances. Surface water temperature (6–29°C) was the only parameter with
predictable seasonal variation; salinity (14–38) was inversely related to rainfall (3.1–485.2 mm month−1) and low values followed extreme precipitation periods in 1997/1998 and 2002/2003 (El Ni?o years). Asterionellopsis glacialis and chlorophyll a presented high concentrations and peak frequency until 1998, when an intense mud deposition occurred with concomitant extreme
rainfall. It affected the surf zone and beach, changing the hydrology and dissolved inorganic nutrient availability. Six phytoplankton
species groups were recognized with distinct responses to this mud deposition. We conclude that large-scale climatic changes,
like El Ni?o Southern Oscillation, in conjunction with human activities significantly altered the phytoplankton ecology of
the highly dynamic Cassino Beach surf zone. 相似文献
490.
The state of knowledge and resources available to issue alerts of precipitation-induced landslides vary across the USA. Federal and state agencies currently issue warnings of the potential for shallow, rapidly moving landslides and debris flows in a few areas along the Pacific coast and for areas affected by Atlantic hurricanes. However, these agencies generally lack resources needed to provide continuous support or to expand services to other areas. Precipitation thresholds that form the basis of landslide warning systems now exist for a few areas of the USA, but the threshold rainfall amounts and durations vary over three orders of magnitude nationwide and over an order of magnitude across small geographic areas such as a county. Antecedent moisture conditions also have a significant effect, particularly in areas that have distinct wet and dry seasons. Early warnings of shallow landslides that include specific information about affected areas, probability of landslide occurrence, and expected timing are technically feasible as illustrated by a case study from the Seattle, WA area. The four-level warning scheme (Null, Outlook, Watch, Warning) defined for Seattle is based on observed or predicted exceedance of a cumulative precipitation threshold and a rainfall intensity–duration threshold combined with real-time monitoring of soil moisture. Based on analysis of historical data, threshold performance varies according to precipitation characteristics, and threshold exceedance corresponds to a given probability of landslide occurrence. Experience in Seattle during December 2004 and January 2005 illustrates some of the challenges of providing landslide early warning on the USA West Coast. 相似文献