Precambrian-Cambrian boundary: recent state of knowledge

The principle of biostratigraphic delimitation of the type lower boundary of the Cambrian System has become generally accepted, despite a lack of recent results which further support this approach. The detection of the most ancient Vendian Ediacara softbodied forms and Cambrian skeletal fauna in a large number of localities worldwide has been the only obvious trend in recent investigations.The present agreement that the base of the Tommotion Stage is the most satisfactory position for the Precambrian—Cambrian boundary is based on the idea that the best type section of the boundary is to be found in the Siberian platform. Such a decision is based largely on the unsatisfactory nature of the arguments for alternative positions.     

利用精密单点定位求解电离层延迟

利用非组合精密单点定位(PPP)可以提取高精度的电离层延迟。测站多径误差会影响伪距和相位测量精度,影响实时PPP电离层延迟提取的精度以及收敛速度。对于静态观测站,利用对GPS卫星地面跟踪的时间重复性进行恒星日滤波可以消除多径误差的影响。通过事后处理提取前几日的码和载波相位残差序列,利用恒星日滤波建立多径误差改正模型,修正实时观测数据,可以改善实时电离层延迟估计性能。对IGS观测站的实测数据分析表明,应用恒星日滤波多径误差修正后,实时电离层延迟提取的精度由0.185 m提高到0.028 m,新进卫星的电离层参数估计收敛时间由80 min减少为35 min。     

Extreme vacuum ultraviolet solar spectra obtained during the SPIRIT experiment aboard CORONAS-F: A catalog of lines in the range 280–330 Å

We present a catalog of 100 lines in the wavelength range 280–330 Å detected by the RES-C spectroheliograph in solar active regions and flares during the SPIRIT experiment aboard the CORONAS-F orbital station. We identified 54 lines. The line intensities recorded during the X3.4 (GOES) solar flare of December 28, 2001, are given. The data reduction procedure is discussed.     

Oxygen Isotope Composition of Zircons from the Talnakh Economic Intrusion of the Noril’sk Province: First Data

Doklady Earth Sciences - This study presents the first results of oxygen isotope analyses (δ18O) collected on zircons from the Talnakh economic intrusion within the Noril’sk province....     

THE CONTENT OF ECOLOGICAL-LANDSCAPE MAPS

The authors describe results of a project involving intermediate-scale mapping of natural environmental complexes of an experimental area in central Belarus'. Three different cartographic models—of landscape dynamics, landscape-geochemical conditions, and composite ecological-landscape conditions—make it possible to organize and synthesize a large volume of material for the assessment of the ecological situation across a number of diverse natural complexes. Translated by Edward Torrey, Alexandria, VA 22308 from: Izvestiya Rossiyskogo Geograficheskogo Obshchestva, Vol. 127, No. 5, 1995, pp. 24-32.     

加权广义逆与秩亏网平差

本文叙述了加权广义逆矩阵的概念。由加权广义逆与线性方程组的解之间的关系,说明了三种秩亏网平差(普通秩亏网平差、拟稳平差、加权秩亏网平差)同属于加权秩亏网平差,只是它们各自选取了不同的权阵P_x,因此均可用加权广义逆来解释它。