Soils as a basis of farming in Slovenia

The great variety of natural factors of landforms, lithology, climate, water, and vegetation in Slovenia has also resulted in great variety of its pedosphere. During the pedogenetic process, 19 groups of soils have developed which in connection with other natural and social factors, influence the use of land for farming in Slovenia. The most significant for the agrarian activity are eutric and dystric cambisols on fluvial sediments on the bottoms of the basins and lowlands in central and eastern Slovenia. Meadows and pastures were arranged on rendzinas on calcocambisols in central and SW Slovenia. Orchards and vineyards are located on eutric cambisol on marl and flysch on the hills of NE and SW Slovenia. Meanwhile the distribution of forests which grow on rendzinas, calcocambisols, and dystric cambisols is influenced more by the landforms and higher altitudes, the inclination of slopes, and lithologic composition than by the soil.     

A model of light-curve synthesizing for dwarf novae and the analysis of the OY Car observations by application of the inverse-problem method

The paper contains a model synthesizing the light curves of novae and novae-like stars, as well as of active close binaries (CB) in the phase of an intensive matter exchange between the components with accretion onto a white dwarf. The model considers the radial and azimuthal temperature distributions in the disk enabling a successful interpretation of asymmetrically deformed light curves characteristic for these systems. The analysis of the observed light curves is performed by using the inverse-problem method (Djuraevi, 1992b) adapted to this model. In the particular case the parameters for the dwarf-novaOY Car are estimated on the basis of the U and B observations (Woodet al., 1989).The synthetic light curves obtained through the inverse-problem solving, as a whole, fit the observations well which indicates that it is possible to estimate the system parameters on the basis of the model proposed here.The obtained results indicate a complex hot-spot structure approximated in the model with two components—a central part and a surrounding spot larger in size. The central hot-spot part (temperature about 10000 K is surrounded asymmetrically by the larger spot lower in temperature (about 7000 K). The radiation of the central hot spot is beamed forward by about 20°. The angular size of the hot-spot central part is about 5°, the centre longitude is 322°, whereas for the surrounding spot the size is about 33° and the longitude of the centre about 300°.For the mass ratio of the componentsq=0.102 one finds for the orbit inclination about 83°.8. The analysis shows that the disk radius is about 51% of the corresponding Roche lobe radius.Based on the U and B light curves the quiescent disk-edge temperature is estimated to about 5500 K (U), i.e. 4400 K (B). The disk-radial-temperature profile is much flatter than in the steady-state-approximation case. Beginning from the edge towards the disk centre the temperature slowly increases attaining about 7200 K (U), i.e. 5700 K (B) near the white dwarf. The differences in the solutions for the U and B light curves can be due to deviations in the disk radiation from the black-body approximation assumed in the present model. Expressed in the units of the distance between the component centres [D=1] the disk size is estimated to about 0.304 [D=1], its thickness to 0.014 [D=1], and the white-dwarf radius to about 0.02 [D=1]. The white-dwarf temperature is about 15000 K.The obtained results are in a relatively good agreement with the system parameters estimated earlier (Woodet al., 1989). This indicates that the proposed model of the system and the corresponding inverse-problem method briefly presented here are fully applicable to the analysis of active CB light curves in this evolutionary phase. Though the model given here includes a number of approximations, it enables an independent procedure in the observational-material analysis based on the light-curve synthesis and on the application of the inverse-problem method. Results obtained by applying such an independent method can also serve as a reasonable way in testing the solutions obtained by utilising the earlier approaches.     

Planetary wave activity in the lower ionosphere during CRISTA I campaign in autumn 1994 (October-November)

On the basis of MEM spectrum analysis, the main planetary scale fluctuations formed in the lower ionosphere are studied over a period of 3–25 days during the CRISTA campaign (October-November 1994). Three dominant period bands are found: 3–5, 6–8 and 15–23 (mainly 16–18) days. For 7–8 and 16–18 day fluctuations, propagation was eastward with wave numbers K = 3 and K = 1, respectively. The magnitude of planetary wave activity in the mid-latitudes of the Northern Hemisphere during the CRISTA campaign seems to be fairly consistent with the expected undisturbed normal/climatological state of the atmosphere at altitudes of 80–100 km.     

An analysis of active close binaries (CB) based on photometric measurements

In order to enable a successful application of the realised CB models (presented in the two former articles of the series) in the analysis of the observed light curves, an efficient method unifying the best properties of the gradient method and of the differential-corrections one into a single algorithm (Djuraevi, 1991) is proposed. This method is realised by modifying the Marquardt (1963) algorithm. The inverse problem is solved in an iterative cycle of corrections to the model elements based on a nonlinear least-square method.The interpretation of photometric observations is based on the choice of optimal model parameters yielding the best agreement between an observed light curve and the corresponding synthetic one. Some of these parameters can be determineda priori in an independent way, while the others are found by solving the inverse problem.The programmes for analysing light curves find the optimal system parameters rapidly, reliably and correctly. The corresponding programme support enables an evident graphic presentation of the results.     

Recent progress in the study of accessory minerals

Mineralogy and Petrology -     

Annual variability of planktonic ostracods (Crustacea) in the South Adriatic Sea

Temporal variability and population structure of planktonic ostracods were investigated for the first time in the South Adriatic Sea during 1996. The maximal total ostracod abundance (1167 ind·100 m⁻³; 69% juveniles, 18% females and 13% males) was recorded in February. Thirteen species of marine planktonic ostracods were identified. Porroecia spinirostris and Archiconchoecia striata dominated the ostracod assemblage, accounting respectively for 62% and 18% of the total abundance. Their annual peaks were recorded during the cold season, which was the period of their intense reproduction, with favourable temperature conditions and lack of predators. The females surpassed the males in abundance in most species. The presence of the mesopelagic species indicated a strong influence of intermediate layer water masses from the Eastern Mediterranean Sea.     

Eigenrays in 3D heterogeneous anisotropic media,Part I: Kinematics

We present a new ray bending approach, referred to as the Eigenray method, for solving two‐point boundary‐value kinematic and dynamic ray tracing problems in 3D smooth heterogeneous general anisotropic elastic media. The proposed Eigenray method is aimed to provide reliable stationary ray path solutions and their dynamic characteristics, in cases where conventional initial‐value ray shooting methods, followed by numerical convergence techniques, become challenging. The kinematic ray bending solution corresponds to the vanishing first traveltime variation, leading to a stationary path between two fixed endpoints (Fermat's principle), and is governed by the nonlinear second‐order Euler–Lagrange equation. The solution is based on a finite‐element approach, applying the weak formulation that reduces the Euler–Lagrange second‐order ordinary differential equation to the first‐order weighted‐residual nonlinear algebraic equation set. For the kinematic finite‐element problem, the degrees of freedom are discretized nodal locations and directions along the ray trajectory, where the values between the nodes are accurately and naturally defined with the Hermite polynomial interpolation. The target function to be minimized includes two essential penalty (constraint) terms, related to the distribution of the nodes along the path and to the normalization of the ray direction. We distinguish between two target functions triggered by the two possible types of stationary rays: a minimum traveltime and a saddle‐point solution (due to caustics). The minimization process involves the computation of the global (all‐node) traveltime gradient vector and the traveltime Hessian matrix. The traveltime Hessian is used for the minimization process, analysing the type of the stationary ray, and for computing the geometric spreading of the entire resolved stationary ray path. The latter, however, is not a replacement for the dynamic ray tracing solution, since it does not deliver the geometric spreading for intermediate points along the ray, nor the analysis of caustics. Finally, we demonstrate the efficiency and accuracy of the proposed method along three canonical examples.