Nettleton’s method is based on the elevation dependence of the surface free-air gravity anomalies and widely used to obtain an optimal average density value by applying e.g. least squares model parameter estimation. Its accuracy, however, strongly depends on how efficiently the regional trends and very local (terrain) effects are removed from the gravity anomalies processed. If the geometry of the topography is fixed then the terrain correction term at the evaluation point
is a linear function of the unknown average topographical density. Therefore it can also be included in the equation system to be solved by adjustment and an estimation of the density can be obtained in one step, without iteration. The results of this simple refinement of Nettleton’s method as well as the distorting effect of the regional trend are demonstrated by a local example. It reviews the gravity survey of a geological structure (known as loess bluff) and its surrounding on the bank of the river Danube. The derived density values increase from
= 1163±543 kg/m
= 1764±113 kg/m
as the gravity anomalies are gradually reduced by regional and local (terrain) effects during data processing. The lab determination of surface loess samples from the area having only 3.5% water content gives 1610 ± 100 kg/m
Topographic masses have a strong impact on the medium and short wavelength components of the gravitational signal generated by the mass of the Earth, thus digital terrain models (DTM) are routinely involved in gravity field modelling. In this study the verification of the Shuttle Radar Topographic Mission (SRTM) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM) which is a joint product of METI (Ministry of Economy, Trade and Industry of Japan) and NASA has been done by comparing them to the points of the horizontal and vertical control networks of Hungary. SRTM data fit better to geodetic ground control points than ASTER GDEM, since some artefacts have been found in ASTER elevation set which impede further use of the latter without any pre-processing. Since SRTM is an “unclassified” surface model including all those points which reflected the scanning radar signal thus tree canopy height has been compared to the differences of SRTM and DTM elevations in a hilly test area in Hungary where a local and accurate DTM having 20 m × 20 m horizontal resolution was available. Considerable agreement was indicated between forest height and model differences. Model differences were evaluated to determine their effect synthetically on gravity related quantities. Their influence on geoid height is insignificant, but the change of the investigated second derivatives of the potential is considerable.
The structure of the lithosphere of the ALPACA (Alpine-Pannonian-Carpathian) region is described by a model containing about 200000 rectangular volume elements (prisms) of variable dimensions defined in the mapping system of Hungary. Forward computations show that the contribution of the structural units (topography and upper mantle) of the lithosphere to the disturbing potential
of the Earth may reach several tenths of E unit at 300 km elevation. The contribution from the sediments is less by a factor of ten but even its magnitude exceeds the planned sensitivity of the satellite on board measurements. It is expected that some regional information about the horizontal density variation of the crust can be deduced from the GOCE data, especially for the density contrast between the lower crust and upper mantle. Since the density distribution of either the topographical masses or the sedimentary complex is much better known than the density jump on the Moho, therefore their effect on the second derivatives of
can be removed from the measurements. The residuals can be interpreted by inversion using the closed analytical formulae available for rectangular volume elements. The modelling approach based on the local planar co-ordinate frame was compared to the polyhedron representation of the same crustal model defined in a global rectangular co-ordinate system. No significant effect of the Earths curva- ture could be indicated for the Moho interface.
This paper presents the phytosociological description of a drained swamp community, Veratro albi-Fraxinetum angustifoliae, so far found only in the Nyírség at Nyírábrány “Kis-kőrises”, “Mogyorósi-erdő”; Vámospércs “Jónásrész-Kőrises”; and Vámospércs “Jónásrész-Buzita”. The habitat of the community is transitional between that of alder swamps (Fraxino pannonicae-Alnetum glutinosae), and hardwood riparian forests (Fraxino pannonicae-Ulmetum). The community is characterised by high proportions of character species of Alnion glutinosae and Molinion coerulei as well as Quercetea pubescentis-petraeae s. l. whereas character species of the order Fagetalia are almost completely absent. It hosts several rare, often threatened species, such as Angelica palustris, Ophioglossum vulgatum, Trollius europaeus and Veratrum album.
Short-term fluctuations of indoor radon may occur due to weather conditions, seismic activity etc. These average out during the year. According to our measurements, in the very same room the yearly average of radon concentration may also change by 25–50% from year to year. This observation may make the comparison of indoor radon levels of houses measured in different years unjustified; large scale radon maps based upon such data are less reliable. Possible causes of such year-by-year changes are discussed empirically. The conclusions may be helpful to foresee long-term tendencies, implied by changes of living habits and by climatic shifts.
Authors:G. Koncz, P. Török, M. Papp, G. Matus, and B. Tóthmérész
Intensification of land use in the last few decades resulted in an increased rate of fragmentation of natural forest habitats. With decreased patch size but increased total borderline length the influence of the surroundings also increased. The extent of influence is especially crucial where the forest stands are adjacent to agricultural lands. We studied the vegetation (cover) and seed bank (soil samples, seedling emergence) along adjacent stands of an abandoned vineyard and edge and interior of an oak forest community (Quercetum petraeae-cerris) widespread in Central-Europe, using five transects (16 m2 plots along each transect). We asked the following questions: (i) How do vegetation and seed bank composition differ between the vineyard and forest interior and (ii) which weeds are able to penetrate into the forest herbaceous understorey vegetation and seed banks from the vineyard? In total, 15 phanaerophytes and 147 herbs were detected. Negatively associated with canopy shading, herb cover proved the lowest in the forest inferior. Few weeds and other ruderals recorded in vineyard penetrated into the forest interior. Mean seed density decreased one order of magnitude from the vineyard to the forest interior (from 20,831 to 2,159 seed/m2). The seed banks of the abandoned vineyard and edge and forest interior were dominated by ruderals, but decreasing proportion of weeds was detected from the vineyard to the forest interior. Characteristic forest herbs possessed at most sparse seed banks. Our results suggest that high canopy cover mitigates the negative impact of surrounding weedy vegetation on the forest herb layer. Therefore, the effect of surroundings is detectable mostly in the seed banks. We can assume that the formation of an increased ruderal herb cover can be foreseen if canopy opens, because the local propagule sources of forest species are missing from vegetation and soil seed banks.
Authors:A. Barouni, L. Bakos, É. Zemplén-Papp, and G. Keömley
The possibility of using characteristic X-ray from radioactive products of reactor activation was investigated with particular emphasis on /n,/, /n,n/, /n,2n/, /n,p/ and /n,/ products with long half lives. The characteristic X-rays emitted are a result of electron capture or internal conversion processes during isomeric transition. First of all the sensitivity and detection limits were investigated.
Authors:J. Orbán, Sz. Halasi, G. Papp, Szilvia Barkó, and Beáta Bugyi
The thermodynamic properties of the cardiac and skeletal a-actin isoforms were studied to characterize the molecular bases
of the functional differences between them with the method of differential scanning calorimetry (DSC). The thermal properties
of the actin filaments were described in the presence of calcium and magnesium ions as well. Based on the calculated free
energy changes the α-cardiac actin filaments appeared to be more stable in its physiologically more relevant, magnesium saturated
form. The magnesium saturated form of the α-cardiac actin filaments seemed to be more stable compared to the calcium saturated
form of it. The enthalpy and entropy changes could differentiate between the α-cardiac and α-skeletal actin isoforms and between
the calcium and magnesium saturated cardiac actin isoforms as well. Our results can demonstrate that the few differences between
the amino acid sequences of the α-actin isoforms have an influence on the thermal properties and maybe on the function of
these proteins as well.
Authors:Beáta Bugyi, G. Papp, Sz. Halasi, and B. Visegrády
In our present study we performed the detailed characterisation of jasplakinolide and phalloidin on the thermal stability
of actin filaments. The heat absorption curves were analysed by using the model established by Sanchez-Ruiz et al. . The analysis provided the activation energies attributed to the heat denaturation of actin filaments in the absence
and in the presence of toxins. The results indicated that there are kinetic differences between the toxin-mediated stabilization
of the Ca2+-and Mg2+-actin filaments. The effect of toxins appeared to be cation dependent.