Geo-hidrodinamika: folyadékdinamikai jelenségek a Föld belsejében = Geo-hydrodynamics: fluid dynamical phenomena in the Earths`s interior

Projektünk célja a Föld belsejében zajló többféle áramlás közül két rendszer vizsgálata volt. A köpenyben zajló termikus konvekció háromdimenziós numerikus modelleredményei feltárták, hogy a vizsgált paraméterek mindegyike befolyásolja a köpenyhőoszlopok számát. A hőoszlopok dimenziótlan területi sűrűsége 2-3 illetve 0,04-0,06 attól függően, hogy a feláramlás a köpeny-mag határról indul vagy a modell kétréteges, és a felsőköpeny hőoszlopok forrástartománya a 660 km-es fázishatár. Szuperkritikus Rayleigh-szám esetén, belső hőtermelés jelenlétében a területi sűrűség értéke ~1. Ezeket az eredményeket a hotspot-listákkal összevetve arra a következtetésre juthatunk, hogy az áramlási rendszer nem tökéletesen egyréteges, a hotspotok alatti feláramlások forrástartománya részben a köpeny-mag határ, részben azonban a 660 km mélységű termikus határréteg lehet. Porózus közegben történő vízáramlás modellezésével megállapítottuk, hogy nagy Rayleigh-szám és kis hidraulikus gradiens esetben poligonális konvekciós cellák alakulnak ki, míg kis Rayleigh-szám és nagy hidraulikus gradiens határesetben egyetlen cellában zajlik a konvekció. Különösen érdekes az eredmény az átmeneti értékeknél, amikor lejtőirányú vagy arra merőleges konvekciós hengercellák alakulnak ki. E "kombinált" áramlási képre a légköri áramlásoknál és Földköpeny konvekciós jelenségei között is találhatunk analógiákat. A felszínközeli térrészek vízáramlásának modellezésében esettanulmányokkal egészítettük ki vizsgálatainkat. | The main goal of our OTKA project was to investigate two types of convection in the Earth's interior. The 3D modeling of mantle convection showed that all the investigated model parameters (Rayleigh number, depth-dependent viscosity, heat production) affect the number of mantle plumes. The areal densities of plumes are 2-3 or 0.04-0.06 depending on the source area of upwelling plumes i.e. the mantle-core boundary or the phase boundary at depth of 660 km, respectively. In case of supercritical Rayleigh number the plume density is ~1. To compare these results with several hotspot lists we can conclude that the source area of mantle plumes are partly the mantle-core boundary and partly the thermal boundary layer at 660 km depth. The numerical modeling of underground water flow in the porous-permeable layers of the crust showed that high Rayleigh number and low hydraulic gradient result in a number of polygon shape convection cells and low Rayleigh number and high hydraulic gradient result in one convective cell. In case of intermediate parameters cylindrical convection cells develop parallel or perpendicular to the slope. Similar circulations can be observed in the atmosphere and in the Earth?s mantle in certain conditions. The results of this modeling were used to interpret groundwater flow observations in the Pannonian basin

Presynaptic Calcium Channel Inhibition Underlies CB1 Cannabinoid Receptor-Mediated Suppression of GABA Release.

CB1 cannabinoid receptors (CB1) are located at axon terminals and effectively control synaptic communication and thereby circuit operation widespread in the CNS. Although it is partially uncovered how CB1 activation leads to the reduction of synaptic excitation, the mechanisms of the decrease of GABA release upon activation of these cannabinoid receptors remain elusive. To determine the mechanisms underlying the suppression of synaptic transmission by CB1 at GABAergic synapses, we recorded unitary IPSCs (uIPSCs) at cholecystokinin-expressing interneuron-pyramidal cell connections and imaged presynaptic [Ca(2+)] transients in mouse hippocampal slices. Our results reveal a power function with an exponent of 2.2 between the amplitude of uIPSCs and intrabouton [Ca(2+)]. Altering CB1 function by either increasing endocannabinoid production or removing its tonic activity allowed us to demonstrate that CB1 controls GABA release by inhibiting Ca(2+) entry into presynaptic axon terminals via N-type (Cav2.2) Ca(2+) channels. These results provide evidence for modulation of intrabouton Ca(2+) influx into GABAergic axon terminals by CB1, leading to the effective suppression of synaptic inhibition

Possibilities and limitations in the utilization of the Neogene geothermal reservoirs in the Great Hungarian Plain, Hungary

Abstract Hungary has favorable geothermal conditions. The paper discusses the thermal and hydrogeologic conditions of the Neogene groundwater reservoir below the Great Hungarian Plain. In the exploration of the reservoir one of the most problematic issues, is the interaction between gravity-driven and overpressured flow regimes, especially along conductive faults. A combination of structural geology supported by seismic interpretation, hydrogeochemistry, and hydraulic evaluations can help to delineate the two flow regimes and determine the origin of the water: meteoric (and thus rechargeable) or syn-sedimentary (and thus non-rechargeable) pore water. These results can be incorporated into basin-scale digital models of the Neogene reservoir. The models can be used to predict the response of the reservoir to the water production and injection, and can help to exploit more efficiently and sustainably the thermal waters of the Great Hungarian Plain reservoir

Analysis Of Low Temperature Impact Fracture Data Of Thermoplastic Polymers

Impact fracture toughness of polypropylene (PP) blends, high density polyethylene (HDPE) and rubber toughened polymethylmethacrylate (RTPMMA) has been studied by means of three-point bending falling weight impact testing at different temperatures ranging from -60 degrees C to room temperature using the cleavage fracture toughness, JC parameter [ASTM E1820-99a]. The latter Fracture Mechanics methodology was chosen due to its simplicity [Fasce et al., 2003]. Traces of the impact tests were analyzed using an inverse methodology just proposed by Pettarin et al. (2003). This methodology makes it possible to obtain from a three-point bending instrumented impact test the mechanical response of the material, discarding the dynamic effects associated with the test. The results show that the average JC values calculated with treated and untreated data are similar for a given material, while the standard deviations are larger when the calculations are made with the untreated data. It is clear that the inverse methodology used to correct the data reduces error propagation, giving place to more precise estimations, and therefore more reliable JC values