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We have found a form of resistance lacking host cell death, effective in cucumber against infection of Pseudoperonospora cubensis , in bean against Pseudomonas phaseolicola and Xanthomonas phaseoli , as well as in pepper against the Obuda pepper virus and Xanthomonas vesicatoria . In addition to the own pathogens of the host plants, this defense reaction, accompanied by cell enlargement and stimulated cell division, was also efficient against pathogen species that are in incompatible relationship with the given host plants (the nonhosts). This general defense reaction may manifest itself in different intensities: in cell enlargement of only a few plant cells or enlargement and proliferation of cells to such a degree that results in compaction of even larger tissue parts.

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Acta Agronomica Hungarica
Authors:
J. Szarka
,
O. Toldi
,
E. Szarka
,
J. Remenyik
, and
et al.

The fact that production is often unsuccessful even when resistant varieties are selected on the basis of the hypersensitive reaction can be attributed to the lack of adequate knowledge on plant disease resistance. In addition to specific plant responses to pathogen species, plants also possess an aspecific defense reaction which, instead of causing rapid tissue destruction, is based on the opposite strategy, protecting the plant against attack by microbes through tissue compaction achieved by cell enlargement and cell division. Genetic analyses carried out in pepper revealed that the general defense reaction was inherited as a monogenic recessive trait (gds). Pathophysiological observations indicate that the stimulus threshold is lower and the reaction rate faster than for specific defense reactions. Biochemical analyses suggest that, unlike plants exhibiting rapid tissue destruction, plants containing the gds gene do not require an oxidative burst elicited by hydrogen peroxide to stimulate the defense mechanism. It was also found that the regulation of the general defense system involves metabolic pathways that are independent of salicylic acid. The general and specific plant reactions form an integrated system of plant defense.

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Abstract  

An apparatus for natural tritium concentration measurement using an ethane-filled proportional counter with anticoincidence shielding is described. The counter characteristics and the counter calibration with internal tritium and external137Cs standards are discussed. Results of tritium analysis of Bratislava rains are presented.

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Journal of Thermal Analysis and Calorimetry
Authors:
J. Orbán
,
Kinga Pozsonyi
,
Krisztina Szarka
,
Szilvia Barkó
,
Emőke Bódis
, and
D. Lőrinczy

Abstract  

The thermodynamic properties of the ADP- and ATP-actin filaments were compared by the method of differential scanning calorimetry. The lower melting point for the ADP-F-actin filament (58.4 vs. 64.5°C for ATP-F-actin) indicated that compared to the ATP-actin filaments its structure was less resistant to heat denaturation. The detailed thermodynamic characterisation of the proteins was carried out by the analysis of the calorimetric enthalpy, the entropy and the free enthalpy changes. All of the determined parameters gave lower values to the ADP-actin filaments than to the ATP-actin filaments. The calculated values of the activation energy also demonstrated that compared to the ADP-F-actin the ATP-F-actin was thermodynamically more resistant to the denaturing effect of heat. Based on all of this information we have concluded that the actin filament prepared from ADP containing magnesium saturated actin monomers at pH 8.0 is thermodynamically less stable than the ones obtained from ATP-actin monomers.

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Abstract  

The radiation situation in Bratislava following the Chernobyl accident is discussed. Measurement results of - and -radioactivity of aerosols are presented. The evolution of the activity ratios in air for some radionuclides is discussed. Their distribution indicates different transport and deposition properties for the volatile and nonvolatile fission products. The results are compared with long-term measurements of anthropogenic radionuclides released to the atmosphere by nuclear bomb tests.

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Acta Geodaetica et Geophysica Hungarica
Authors:
A. Ádám
,
P. Bencze
,
F. Märcz
,
D. Martini
,
G. Sátori
,
L. Szarka
,
J. Verő
,
V. Wesztergom
, and
B. Zieger

This is a summary of the activities of the Geophysics Department of the Geodetic and Geophysical Institute in the framework of the Scientific School Earth Electromagnetism. Ten reports cover the most important topics and emphasize interconnections between the different phenomena. The topics include interplanetary space, magnetosphere and ionosphere, electromagnetic waves in a wide spectrum, and electromagnetic induction, also within a wide range of frequencies and applications. Geomagnetism, especially the Széchenyi István Geophysical Observatory Nagycenk with a lot of different recordings of electromagnetic parameters play important roles in most topics.

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Acta Geodaetica et Geophysica Hungarica
Authors:
A. Ádám
,
P. Bencze
,
J. Bór
,
B. Heilig
,
Á. Kis
,
A. Koppán
,
K. Kovács
,
I. Lemperger
,
F. Märcz
,
D. Martini
,
A. Novák
,
G. Sátori
,
S. Szalai
,
L. Szarka
,
J. Verő
,
V. Wesztergom
, and
B. Zieger

The paper describes research in geomagnetism and aeronomy carried out in the framework of a project organized by the Geodetic and Geophysical Research Institute of the Hungarian Academy of Sciences. It includes the development of the instrumentation of the Nagycenk Geophysical Observatory (geomagnetic measuring systems, ionosonde), moreover other instrumental and methodological developments, too. Observatory data are available in a database. Based on results of the Nagycenk and Tihany observatories and on data of permanent and temporal networks, long-term trends of different electromagnetic parameters were investigated. Thus geomagnetic activity was found secularly increasing, a decrease of the atmospheric electric potential gradient and a 11-year modulation of the winter/December attenuation of the geomagnetic pulsation activity were confirmed. Several possibilities (pulsations, whistlers, modelling) were used to improve knowledge about structure and parameters of the magnetosphere. Electromagnetic precursors of earthquakes were looked for. A significant increase of understanding was obtained in connection with Schumann resonances and electromagnetic transients caused by lightning. It was shown that see-coasts influence characteristically changes in ionospheric trends ( h m F2). When looking for the effect of the global climate changes in the subsurface electric resistivity, an example was discovered for the decrease of the resistivity due to infiltrating water from precipitation. Electromagnetic exploration of tectonically conditioned weak zones was continued, too.

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