Acceleration time-scale in an ultrarelativistic shock     

Janusz Bednarz 《Monthly notices of the Royal Astronomical Society》2000,315(3):L37-L40

The acceleration mechanism in ultrarelativistic shocks is investigated using Monte Carlo simulations. We apply a method of discrete small-amplitude particle momentum scattering to reproduce highly anisotropic conditions at the shock and describe the acceleration mechanism carefully. The obtained acceleration time equals 1.0 r _g c if the spectral index reaches the value of 2.2, independent of physical conditions in the shock. Some other parameters of the acceleration process are also provided.  相似文献   

Analysis of particulate matter concentrations in mazovia region, central poland, based on 2007–2010 data     

Aleksander Pietruczuk  Janusz Jarosławski 《Acta Geophysica》2013,61(2):445-462

Measurement results of PM10 (particulate matter with diameters below 10 μm) concentrations performed at four stations in central Poland (2007–2010) were analyzed in terms of levels and distributions of concentrations, the number of exceedances of the limit values and the causes of these exceedances. PM10 levels were similar at suburban and rural stations, except of one station located in the vicinity of a busy street. The median of PM10 concentration ranged from 26 μg/m³ at suburban station to 44 μg/m³ at Warsaw Kerb station. Seasonal variability analysis of PM10 concentration revealed an additional maximum beyond the usual autumn-winter one. This maximum occurred in April at all stations, and corresponded to seasonal wildfires activity and dust activation in Eastern Europe. Cluster analysis of back-trajectories revealed that PM10 concentrations depend on the direction of advection of the incoming air; the highest values are registered for air of regional and southern origins, while the lowest are for the airmasses coming from the north and northwest direction.  相似文献   

Dim prospects for radar detection of Europa's ocean     

Janusz Eluszkiewicz 《Icarus》2004,170(1):234-236

The thickness of a porous regolith on Europa is estimated to be ∼1 km. Provided that this regolith contains as little as 1% by volume of cavities with sizes comparable to the radar wavelength, its presence poses an insurmountable obstacle in the search for Europa's ocean by means of a sounding radar.  相似文献   

A New Mantispid-Like Species of Rhachiberothinae(Neuroptera:Berothidae)from Baltic Amber,with a Critical Review of the Fossil Record of the Subfamily     

Vladimir N. Makarkin  and Janusz Kupryjanowicz 《《地质学报》英文版》2010,84(4):655-664

<正>Whalfera wiszniewskii sp.nov.is described from the Late Eocene Baltic amber.The genus Whalfera is considered as the only fossil genus confidently assigned to the Rhachlberothinae.Others previously placed in this subfamily belong to Paraberothinae(except perhaps for Oisea).The Late Eocene/present Rhachiberothinae and the Cretaceous Paraberothinae are considered to be the subfamilies of Berothidae.  相似文献   

Lignin degradation products as palaeoenvironmental proxies in the sediments of small lakes     

Karol Kuliński  Joanna Święta-Musznicka  Andrzej Staniszewski  Janusz Pempkowiak  Małgorzata Latałowa 《Journal of Paleolimnology》2007,38(4):555-567

The quantity and quality of lignin phenols (Σ8, Λ, S/V, C/V and (Ad/Al)_v) in the sediments of three small Lobelia lakes with neither inlets nor outlets were investigated and compared with palynological data and lithology of the profiles. The method of alkaline CuO oxidation was used. Substantial differences with respect to sedimentary lignin concentration and provenance recorded along the profiles and among the sites are in good agreement with pollen data describing the dominant type of vegetation and with indices of soil erosion in the lakes’ catchments. This relation shows that the compositions of lignin degradation products in these lakes are closely related to the local environmental conditions. In all the lakes gymnosperm wood is the main source of lignin products; however, each lake is characterized by different S/V index values. Especially good correlations were obtained between pine pollen proportions in sediments and the S/V index. The correlation between the C/V and (Ad/Al)_v indices indicates a higher degradation of organic matter when non-woody tissue is more abundant. This pilot study illustrates the usefulness and potential for a wider application of lignin oxidation products in palaeoecological reconstructions. This kind of data would be of special importance when investigating local presence/absence of woody plants and the role of angiosperms/gymnosperms in local vegetation. Estimates of lignin biodegradation levels, as well as the data on diagenetic processes, may afford supplementary information on possible disturbances in sedimentation.  相似文献   

On the radio-frequency emission from the Geminga pulsar     

Janusz A. Gil  David G. Khechinashvili  & George I. Melikidze 《Monthly notices of the Royal Astronomical Society》1998,298(4):1207-1211

The famous neutron star Geminga was until quite lately the only pulsar undetected in the radio regime, though observed as a strong pulsating γ- and X-ray source. Three independent groups from the Pushchino Radio Astronomy Observatory (Russia) reported recently the detection of pulsed radio emission from Geminga at 102.5 MHz, i.e., the first detection of the radio pulsar PSR J0633 + 1746 by Kuz'min &38; Losovskii, Malofeev &38; Malov and Shitov &38; Pugachev. This pulsar exhibits the weakest radio luminosity known. Its average pulse profile appears to be very wide, filling an entire 360° pulse window according to Kuz'min &38; Losovskii.   We present a model explaining the peculiarities of the Geminga radio pulsar, based on the assumption that it is an almost aligned rotator. The electromagnetic waves generated in the inner magnetosphere reach the region within the light cylinder with a weak magnetic field (at distances of a few light cylinder radii), where they are strongly damped due to the cyclotron resonance with particles of magnetospheric electron–positron plasma. The lowest frequencies that can escape are determined by the value of the magnetic field in the region where the line of sight passes through the light cylinder. The specific viewing geometry of an almost aligned rotator implies that the observer's line of sight probes the emission region near the bundle of the last open field lines. This explains the unusually weak emission from Geminga's low-frequency radio pulsar.  相似文献   

Sulphidizing reactions in the flotation of oxidized copper minerals,I. Chemical factors in the sulphidization of copper oxide     

Sergio Castro  Jorge Goldfarb  Janusz Laskowski 《International Journal of Mineral Processing》1974,1(2):141-149

The rate and extent of the heterogeneous reaction that takes place between dissolved sodium sulphide and synthetic tenorite is studied for a wide range of sodium sulphide to copper oxide ratios. Besides the sulphidization with the formation of a copper-sulphide layer, a substantial oxidation of sulphide ions takes place at the surface of the solid. The extent of both types of reactions is quantitized by combining specific analytical methods.The results are discussed in terms of possible mechanisms and of their implications in the sulphidization process applied in the flotation of oxidized copper ores.  相似文献   

Sulphidizing reactions in the flotation of oxidized copper minerals,II. Role of the adsorption and oxidation of sodium sulphide in the flotation of chrysocolla and malachite     

Sergio Castro  Heriban Soto  Jorge Goldfarb  Janusz Laskowski 《International Journal of Mineral Processing》1974,1(2):151-161

The rate of consumption of sulphide in the sulphidizing reactions of malachite and chrysocolla has been measured. The oxidation of sulphide ions at the surface of sulphidized chrysocolla was shown to take place. The influence of thiosulphate anions on the xanthate flotation of sulphidized malachite and chrysocolla was investigated and it was shown to depress the flotation of chrysocolla strongly.The result suggest, that the presence of thiosulphate as a product of simultaneous oxidation can be one of the reasons for the more difficult flotation of sulphidized chrysocolla.  相似文献   

Gemeinsames umfassendes Umwelt-Aktionsprogramm für die Ostsee     

Prof. Dr. Janusz Kindler 《Ocean Dynamics》1991,44(5-6):241-244

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A model for heat and water balance estimation and its application to land use and climate variation     

Janusz Olejnik  Andrzej Kedziora 《地球表面变化过程与地形》1991,16(7):601-617

This paper presents a method, which has been recently developed in the Department of Agrometeorology of the Poznań Agricultural University, for estimating heat balance components based on standard meteorological data, plant development stage, and land-use conditions. Estimates of latent heat flux components made it possible to obtain values of areal evapotranspiration and surface runoff. The method was applied in four catchment areas in Central Poland under present climatic conditions as well as under new, expected climatic conditions caused by an increase of ‘greenhouse gases’ in the atmosphere. Some changes in land use were also considered. The results show significant changes in the water balance when comparing present and future conditions of precipitation and evapotranspiration.  相似文献