Truncation errors of selected finite difference methods for two-dimensional advection-diffusion equation with mixed derivatives

The spread of a passive contaminant in an open-channel reach is considered with use of a two-dimensional advection-diffusion equation with the included off-diagonal dispersion coefficients. This paper presents the calculation of truncation errors, namely numerical diffusion and numerical dispersion for various finite difference schemes. The accuracy of the considered finite-difference approximations is analysed by deriving and studying the relevant modified partial differential equation.     

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

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.     

Measurable difference in Cherenkov light between gamma and hadron induced EAS

We describe the possible measurable difference in the Cherenkov light component of EAS induced by an electromagnetic particle (i.e., e⁺, e⁻ or γ) and induced by a hadron (i.e., proton or heavier nuclei) in the TeV range. The method can be applied in experiments which use wave front sampling method of EAS Cherenkov light detection (e.g., THEMISTOCLE, ASGAT).     

Influence Of The Atmosphere On Earth Rotation: What New Can Be Learned From The Recent Atmospheric Angular Momentum Estimates?

The interaction between the atmosphere and the underlying solid mantle is oneof the most important sources of changes in all three components of theEarth's rotation vector on different time scales. In this paper the NCEP/NCARreanalysis time series of four times daily atmospheric effective angularmomentum (EAM) estimates is used to investigate some selected aspects of theatmospheric influence on Earth rotation. Emphasis is placed on thecontroversial features which were difficult or impossible to study using theoperational EAM data, such as excitation of the free oscillations in polarmotion, the Chandler wobble (CW) and the free core nutation (FCN), or theroles of diurnal and semidiurnal atmospheric tides and atmospheric normalmodes in the rotational dynamics of the Earth.     

Palaeobathymetric model of the Upper Senonian Flysch sediments of a part of the Silesian Basin (Polish Carpathians)

The occurrence of redeposited sediments and foraminiferids within the Upper Senonian deposits of the Silesian Unit (Northern Carpathians) have allowed a reconstruction of a part of the southern slope of the Silesian Basin. Three main zones have been established with specific sediments and associations of foraminiferids; basin plain, slope and upper slope-shelf which correspond to part of the “Recurvoides” and “Marssonella” associations sensu Haig (1979). Nine species of Foraminiferida from the uppermost associations are described.     

Relativity and space-time measurements

The new reconstruction of special relativity (SR) is presented. The question of length and time measurements forms the basic plane of our search. The question why Milne's procedure, applied to clocks synchronization by means of light signal, supersedes the Einsteinian procedure by means of moving clock, is elaborated. According to H. E. Ives' hints the consistency of velocity notion in SR is reanalysed. The justification of the light postulate from the point of view of measurement procedures and anti-absolutistic heuristics of SR is discussed. The new correspondence relation between SR and Ives' space-time theory is presented. The fundamental problems related to operationistic interpretation of SR and to research programmes of kinematics are discussed in the new theoretical fashion.     

Bellert's general relativity theory

In this paper, new ideas from our previous paper (Rydzyska, 1989)-i.e., problems connected with the new equivalence principle-have been developed. It is conformed, that certain static particles from Bellert's space-time are equivalent to a free particle from classic Milne's space-time. Mention is made of the algebraic structure of Bellert's space-time from (Rydzyska, 1990b). The space-time interval in this space-time, and its connection with a probability and the physical meaning of this interval and probability, has been defined. In the last section we derive dynamical equations for Bellert's space-time, i.e., we do the foundations of Bellert's general relativity theory.