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51.
<正>The oldest representative of the genus Megarhyphus Kovalev(Diptera:Anisopodidae)is described from the Lower Jurassic(Sinemurian)of England.A summary of our knowledge of Jurassic Anisopodidae is given.  相似文献   
52.
Presented here are high spatial and spectral resolution Chandra X-ray observations of the famous interacting galaxy pair, the Mice, a system similar to, though less evolved than, the well-known Antennae galaxies. Previously unpublished ROSAT High Resolution Imager data of the system are also presented.
Starburst-driven galactic winds outflowing along the minor axis of both galaxies (but particularly the northern one) are observed, and spectral and spatial properties, and energetics are presented. That such a phenomenon can occur in such a rapidly evolving and turbulent system is surprising, and this is the first time that the very beginning – the onset, of starburst-driven hot gaseous outflow in a full-blown disc–disc merger has been seen.
Point-source emission is seen at the galaxy nuclei, and within the interaction-induced tidal tails. Further point-source emission is associated with the galactic bar in the southern system. A comparison of the source X-ray luminosity function and of the diffuse emission properties is made with the Antennae and other galaxies, and evidence of a more rapid evolution of the source population than the diffuse component is found. No evidence for variability is found between the Chandra and previous observations.  相似文献   
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Occurrence of winter air temperature extremes in Central Spitsbergen   总被引:1,自引:1,他引:0  
The occurrence of daily air temperature extremes in winter in Central Spitsbergen in the period 1975–2008 was analysed. The mean winter temperature was found to be increasing by approximately 1.65°C per decade. Negative extremes were becoming less frequent, decreasing at a rate of approximately 5 days per decade, whereas the frequency of positive extremes showed a small (2 days per decade) but insignificant positive trend. Furthermore, circulation patterns responsible for positive and negative temperature extremes were analysed. Composite maps of the sea level pressure (SLP) and 500-hPa geopotential heights (z500 hPa) means and anomalies were constructed for the days with positive and negative extremes. Circulation patterns causing extremely warm winter days are characterised by a cyclonic centre or a low pressure trough over the Fram Strait. Cyclones located west of Spitsbergen with a warm sector over the archipelago bring warm air masses from the southern quadrant. On extremely cold days, the cyclone centres are usually located over the Barents Sea. This SLP pattern implies airflow from the north and northeast that brings cold Arctic air to the North Atlantic. Another factor in the occurrence of the temperature extremes in Central Spitsbergen is the sea-ice cover. Negative temperature extremes usually occur together with a high concentration of sea ice, particularly in the middle and end of winter.  相似文献   
56.
Synoptic conditions of extreme rainwater pollution episodes, evidenced by maximum values of parameters measured in the protected area of Wielkopolski National Park (western-central Poland), were analysed in this study. Precipitation samples were tested for the following parameters: pH, electrical conductivity and the concentration of the following elements: F-, Cl-, NO2-, NO3-, PO43-, SO42- and Na+, NH4+, K+, Mg2+, Ca2+. It was assumed, that in winter, western advection of Atlantic air masses was the most frequent aerosol and pollution transport scenario for the investigated area. In summer the most heavily pollution occur at the intensified meridional flow over the central Europe, indicating advection of cooler air from northern Europe and the North Sea. In most of cases, the weather conditions causing extreme concentration of examined pollutants, were determined by the movement of weather fronts over considerable parts of Poland and by precipitation caused by those fronts.  相似文献   
57.
As has been demonstrated in recent years, the heterogeneities of coeval magmas can be more successfully revealed by zoned megacrysts rather than by analysis of the whole rocks hosting them. Here, the geochemical heterogeneities of feldspar megacrysts from the Karkonosze granite, Poland, are investigated by LA-ICP-MS. The crystals are the product of migration and growth in regions of poorly mixed magmas. 3D-modeling of the Ba, Sr, and Rb distributions emphasizes the importance of micro-domain growth morphologies. Two models of element behavior—a relative concentration model and a composition gradient model—provide a potentially effective tool for tracking the mixing process on a microscale. Measured concentrations of elements of different mobilities do not agree with what might be expected from the mixing of two end-member magmas. If mixing was the only process occurring, linear correlations between the concentrations of any two elements should be observed; this, however, is not the case. For combinations of any two of the three elements, modeling reveals differing non-linear correlations between concentrations. The megacryst heterogeneities provide an insight into how mixing magmas are chaotically advected to growing crystals and the degree of inter-magma element exchange between the magmas.  相似文献   
58.
Experiments were conducted to study the airborne microbial contamination generated by a wastewater treatment plant (WWTP). Aerosol samples were collected simultaneously, by sedimentation and impact methods, from the area and the surroundings of the WWTP. Total colony forming units (CFUs) of heterotrophic bacteria (HPC), as well as members of the Enterobacteriaceae, staphylococci, enterococci, actinomycetes, and microscopic fungi were determined. Bacterial (HPC) concentrations ranged between 101 and 104 CFU/m3, fungi 0 and 104 CFU/m3. Higher numbers of HPC bacteria in air samples were observed in summer, fungi in autumn. The main emission of microorganisms to atmospheric air was from the mechanical sewage treatment devices of the WWTP. The facilities of the biological sewage treatment of the plant did not generate large amounts of bioaerosols. In the air obtained from the premises of the WWTP, 25 species of the Enterobacteriaceae were isolated (Salmonella spp., Klebsiella pneumoniae, Escherichia coli). At the fence and in the surroundings only Pantoea spp. were identified. This suggests that the sewage bacteria were mainly discharged in the area of the WWTP. The presence of enteric bacteria, especially Enterobacteriaceae reflects the level of air pollution with bioaerosols from sewage and is an important factor during monitoring the quality of the air around WWTPs.  相似文献   
59.
The Borrobol Tephra has been identified as one of the key tephra horizons for the Lateglacial time period but it also exemplifies many of the promises and problems of tephrochronology. Additional horizons with similar major element composition and approximately the same age have been identified around the North Atlantic region. Here, we revisit the Borrobol Tephra identified at two Swedish sites, Hässeldala port and Skallahult, and also the Borrobol type‐site in Scotland. We present the first set of minor element data (trace and rare earth analyses) along with new analyses of major elements from these three sites. The analysed minor and the trace elements have a similar signature; however, the glass from the Scottish type‐site seems to imply two populations. To answer if this truly represents two populations, or if it reflects magmatic differentiation additional and larger data sets of minor elements are needed. The new major elements are compared to other Borrobol‐type tephras identified in the North Atlantic region. Our results are in line with earlier investigations, which showed no differences in major elements. Further, comparison of minor elements from glass analyses from our sites with those for eruptions associated with Icelandic central volcanoes implies an Icelandic origin for the Borrobol‐type tephras.  相似文献   
60.
Among the schemes for earthquake forecasting, the search for semi-periodicity during large earthquakes in a given seismogenic region plays an important role. When considering earthquake forecasts based on semi-periodic sequence identification, the Bayesian formalism is a useful tool for: (1) assessing how well a given earthquake satisfies a previously made forecast; (2) re-evaluating the semi-periodic sequence probability; and (3) testing other prior estimations of the sequence probability. A comparison of Bayesian estimates with updated estimates of semi-periodic sequences that incorporate new data not used in the original estimates shows extremely good agreement, indicating that: (1) the probability that a semi-periodic sequence is not due to chance is an appropriate estimate for the prior sequence probability estimate; and (2) the Bayesian formalism does a very good job of estimating corrected semi-periodicity probabilities, using slightly less data than that used for updated estimates. The Bayesian approach is exemplified explicitly by its application to the Parkfield semi-periodic forecast, and results are given for its application to other forecasts in Japan and Venezuela.  相似文献   
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