Aquatic hyphomycetes or Ingoldian fungi are the major decomposers of leaf litter in temperate aquatic ecosystems. Role of leaf litter quality in structuring hyphomycete communities is intensively discussed among hydrobiologists. Therefore, an adequate sampling strategy of the leaf litter is essential in this field. The present paper aims analysing the appropriate sample size of leaf litter with various diversity and evenness combinations taken from streambeds in the temperate deciduous forest zone.Leaf litter in the streambed was sampled at four stream sections of two tributaries of the Morgó stream in the Börzsöny Mts, Hungary. The tributaries differed in water chemistry, altitude and riparian vegetation. To analyse species number-sample size relations, species saturation diagrams were drawn and statistically evaluated.Results showed that: (1) a sample size of 500 leaves sufficiently describes the species composition of leaf litter taken from streambeds in the temperate forest zone, in cases of low diversity forest stands and high diversity forest stands coupled with high evenness; and (2) for forest sites with high diversity coupled with low evenness values a litter sample composed by 800-1000 leaves is advised to investigate to achieve satisfactory estimation of the species composition of leaf litter.The sampling methods described in this paper are proposed for studies where estimation of leaf litter composition is required to understand the available substrate quality for litter decomposing organisms.
The paper advocates a more extensive use of additive trees in community ecology. When the distance/dissimilarity coefficient is selected carefully, these trees can illuminate structural aspects that are not obvious otherwise. In particular, starting from squared distances based on presence/absence data, the resulting trees approximate relationships in species richness, a feature not available through other graphical techniques. The construction of additive trees is illustrated by three actual examples, representing different circumstances in the analysis of grassland community data.
Experience shows that the nuclear power plant can be safely designed for vibratory effects of earthquakes. Contrary to this, the plants can be heavily damaged by effects of earthquake-induced phenomena like tsunami, soil liquefaction after surviving the ground shaking effects. In the paper, the nuclear power plant’s safety analysis methodology is outlined for the case of soil liquefaction. In the paper the methodology for safety analysis of nuclear power plants for the case of liquefaction is outlined for both deterministic and probabilistic cases. It is shown, how the analysis of consequences of the liquefaction has to be embedded into the overall analysis of plant seismic safety. The selection of hazard and the fragility assessment methods is discussed from the point of view of needs of safety analysis.
Manna ash (Fraxinus ornus L.) is a typical deciduous tree of South European distributioin reaching the northern border of its range in the Carpathian Basin. The correlation between age and basal diameter of this tree was analysed in three ecologically contrasting habitats, as follows. (1) Succesional habitat. Abandonedframland with scattered occurrence of manna ash as a colonisong tree of this area. (2) Austrian pine plantation, where manna ash often forms a spontaneous subordinate tree or shrub layer. (3) Cotino-Quercetum pubescentis, the naturla vegetation on south facing calcareous hillslopes in Hungary, where Quercus pubescenes Willd. and Fraxinus ornus codominate in the low canopy. At each sampling site 21 individuals were selected with an even distribution within circumference categories ranging from 6cm to 60cm. Circumference measurements were made at the base of the trunk, or cores were taken by a driller. Linear regression analysis was applied to test the correlation between age and diameter.
The Discrete Element Method (DEM) for describing the action mechanism between soil and sweep tool can be used to perform a detailed analysis of draft force, soil cutting, clod-crushing and loosening by taking into account the tillage speed and the three soil phases. This study describes the simulation of the 3D DEM soil model and a cultivator sweep digitized with a 3D scanner, showing the soil—sweep interaction as a function of implement draft force and implement operating speed.
The suitability of the model is validated by comparing the results of laboratory and simulated shear tests (static validation) with the results of soil bin tests (dynamic validation). The mechanical parameters of the sandy soil used for the soil bin tests were measured using the direct shear box test. Cohesion for the soil model used during simulations was set using the parallel bond contact model, where the determining factors were the Young modulus for particle contact (Ec) and bonding (Ēc), the Poisson’s ratio (nu), the normal (σ) and shear (τ) bond strength and the radius of the related volume (cylinder). Once the DEM model parameters were set, the draft force values measured during dynamic testing were harmonized using the value for viscous damping (ci).
The dynamic soil—sweep model was validated using the viscous damping applied based on the simulated and measured draft force values. The validation of the Young modulus to 0.55e6 Pa (Kn = 1.73e4 N/m, Ks = 8.64e3 N/m) enabled us to set the draft force values of the model for different speeds (0.8–4.1 m/s) with an accuracy of 1–4%.
During the analysis of changes in tillage quality, the developed dynamic soil—sweep model showed a high degree of porosity (48%) due to grubbing in the attenuated speed range (0.5–2.1 m/s), and a decreasing tendency (0.41–0.39%) in the non-damped speed range (2.1–4.1 m/s). After the initial equilibrium state, the ratio of average particle contacts for the given porosity decreased in the attenuated speed range (coord number: 4.8), and a slight decrease was also found above speeds of 2.1 m/s (coord number: 5.2). In the model, clod-crushing was examined based on the ratio of sliding contacts, and we found a continuous increase (sliding fraction: 2–15%) in the speed range used for the simulation (0.8–4.1 m/s).
Authors:Tamás Szegi, E. Tombácz, Zs. Czibulya, J. Akagi and A. Zsolnay
A lot of attention is
being paid to the understanding of the influence of soil degradation on human
life at the beginning of the 21
century. Among the many types of
degradation processes, structural degradation is widespread on huge areas in
Europe. For better control, it is needed to get familiar with all the driving
forces, the main reasons that lead to soil degradation (Várallyay, 2003; ESB, 2002). In addition to unfavourable
natural conditions, inappropriate land use has an important impact on
micro-aggregate stability and the rate of tolerance to deformation forces, such
as cultivation and erosion. Rheological
measurements provide new quantitative information on particle-particle
interaction, the colloidal stability and structure of concentrated suspensions
in general. Field samples from loess derived agricultural soils were
investigated. In addition to general laboratory analyses (soil organic matter
content, CEC), conventional, simple aggregate
stability, and water retention measurements and rheology were applied for
investigating the micro-aggregate stability of the samples. The evaluation of
pseudoplastic flow curves indicated close relationships between the strength
and stability of the physical network and the composition of the suspensions.
These soil properties have strong, well-defined connection with tolerating
cultivation and capability for erosion.
Authors:E. Kovács, P. Tóth, Cs. Juhász and J. TamáS
There are numerous biological agents including bacteria such as Brucella suis, B. abortus, Francisella tularensis, Burkholderia mallei, Coxiella burnetii, Yersina pestis, Bacillus anthracis and Chlamydia psittaci, viruses such as Variola major and V. minor, Flavivirus and Hantavirus, and toxins such as Botulinum toxin produced by the bacterium Clostridium botulinum, Staphylococcus enterotoxin B and Trichothecene mycotoxin reported to have potential to cause illness via water consumption. In the recent years, biological threat prevention for urban water supply systems has been of special interest worldwide, thus, protection against biological agents requires adequate knowledge, available water treatment technologies and preparedness. In this review, the history of biological threat via public water supply, as well as selected early detection methods, prevention strategies and risk assessment models are detailed.
Authors:B. Sandor, J. Papp, Gy. Mozsik, J. Szolcsanyi, Zs. Keszthelyi, I. Juricskay, K. Toth and Tamas Habon
Capsaicin is a well-known component of red pepper. Recent studies have shown that capsaicin could prevent gastric ulcer provoked by various NSAID-s like acetylsalicylic acid (ASA). Primary objective of this human clinical phase I trial was to investigate whether two different doses of capsaicin co-administered with ASA could alter the inhibitory effect of ASA on platelet aggregation. 15 healthy male subjects were involved in the study and treated orally with 400 μg capsaicin, 800 μg capsaicin, 500 mg ASA, 400 μg capsaicin+500 mg ASA and 800 μg capsaicin+500 mg ASA. Blood was drawn before and 1, 2, 6 and 24 hours after the drug administration. After that epinephrine induced platelet aggregation was measured by optical aggregometry. Between treatments, volunteers had a 6-day wash-out period. Our results showed that capsaicin had no effect on platelet aggregation, while as expected, ASA monotherapy resulted in a significant and clinically effective platelet aggregation inhibition (p ≤ 0.001). The combined ASA-capsaicin therapies reached equivalent effectiveness in platelet aggregation inhibition as ASA monotherapy. Our investigation proved that capsaicin did not influence the inhibitory effect of ASA on platelet aggregation, thus the capsaicin-ASA treatment would combine the antiplatelet effect of ASA with the possible gastroprotection of capsaicin.