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Showing papers by "Hungarian Academy of Sciences published in 1980"


Book ChapterDOI
TL;DR: The spin-projected extended Hartree-Fock (HF) method as discussed by the authors is the basic one in quantum chemistry and has been applied to many-electron wave functions.
Abstract: Publisher Summary This chapter focuses on the spin-projected extended Hartree–Fock (HF) method. The HF method, in its most usual form, applies the restriction for the one-electron functions that (for closed-shell systems) two electrons with opposite spins are put on the same spatial orbital. Almost all the methods used in quantum chemistry are based on the well-known variation theorem. Choosing the type of the trial wave function used in the variation procedure, one must take into account a great number of different factors—for example, the given class of the wave functions must be adequate to describe the most important physical features of the system, contain as many free variational parameters as feasible from the computational point of view, etc. The one-particle approximations-the Hartree–Fock method and its generalizations-are of upmost importance in this respect. This is one of the reasons why just the HF or selfconsistent field (SCF) method is the basic one in quantum chemistry. Many-electron wave function is approximated as a single Slater determinant—such as, an antisymmetrized product of functions each of which depends on coordinates of only one electron. These one-electron functions (orbitals) are then optimized in a variational way. In addition, a number of actual calculations are also done by using the “extended Hartree–Fock” (EHF) method and the related approaches; these clarified the possibilities and limitations of the method.

201 citations


Journal ArticleDOI
TL;DR: Biochemical measurements indicate that the pontine-medullary noradrenergic cell groups are the source of hypothalamic norepinephrine, and no strict topographical organization seems to be present either in their origin or their termination.

166 citations


Journal ArticleDOI
TL;DR: A brief survey on the state of the art in tracer adsorption studies can be found in this paper, where the main trends in the investigations are illustrated through examples taken from the results reported in the seventies.

164 citations


Journal ArticleDOI
TL;DR: In this article, a theoretical description of the etch-track evolution in solid state nuclear track detectors is considered for different initial conditions, for the cases of constant and varying track etch rates, isotropic and anisotropic bulk etching as well as for thick and thin detectors.

158 citations


Journal ArticleDOI
TL;DR: H2‐receptors are involved in the activation of adenylate cyclase of the capillary fraction of the guinea pig cerebral cortex, and this action elicits a twofold stimulation in the accumulation of cyclic AMP in this capillary fractions.
Abstract: A fraction enriched in capillaries has been prepared from the guinea pig cerebral cortex. The purity of this fraction was checked by light- and electron-microscopic examination and by its high enrichment in alkaline phosphatase and γ-glutamyl transpeptidase. In the capillary-rich fraction, the endogenous level of histamine was 1.9%’of that measured in the initial hornogenate. The histamine-synthesizing enzyme, I-histidine decarboxylase, and the metabolizing enzyme, histamine-N-methyltransferase, were barely detectable. In addition, histamine elicits a twofold stimulation in the accumulation of cyclic AMP in this capillary fraction with an EC50 of 5 γM. Agonists and antagonists of the two types of histamine receptors (H1 and H2) were used for the characterization of the receptors mediating this action: H2-receptor agonists were able to activate the adenylate cyclase with “relative potencies” similar to that found on typical H2-receptors, and cimetidine, a specific H2-receptor antagonist, competitively inhibited the response to histamine with a K1 value reflecting its interaction with a single population of H2-receptors. On the contrary, data obtained with H1-receptor agonists and antagonists reflect their interaction with H2-receptors rather than H1-receptors. Thus H2-receptors are involved in the activation of adenylate cyclase of the capillary fraction.

154 citations


Journal ArticleDOI
TL;DR: A model for the induction of early ecdysone puffs is proposed, assigning a key role to the 2B5 puff product in stimulating other early puffed, and it is suggested that defects in the activity of early puffs in the mutant t10 may cause underdevelopment of late puffs.
Abstract: Larvae homozygous or hemizygous for the l(l) t435 mutation located within the early ecdysteroid puff 2B5, or carrying a deletion of the 2B5 band, die at the end of the third larval instar. In the salivary gland chromosomes of these larvae only intermoult puffs are detected. If these salivary glands are incubated in vitro with 20-OH ecdysone for 6 h the intermoult puff 68 C remains large, some early puffs (74EF and 75B) are induced to 30–40% of their normal size, other early (63F) and all late puffs (62E, 78D, 82F and 63E) are not induced at all. Puff 2B5 reaches its normal size but does not regress after 6h incubation with 20-OH ecdysone, as it does in normal stocks. The data obtained in this study show the existence of a locus (or loci) in the band (puff) 2B5 which is necessary for the normal response of the salivary gland chromosomes to the hormone 20-OH ecdysone.

141 citations


Journal ArticleDOI
TL;DR: In this article, the formation and deposition of fatty acids in carp maintained on diets differing in total fat as well as linolenic acid content was investigated by following the incorporation of (1- 14 C)-acetate into liver total- and phospholipid fatty acids at two extreme temperatures (5° and 25°C).

140 citations


Journal Article
TL;DR: The electron-microscopic investigations suggest that the failure of the Kupffer cells to incorporate carbon during the reticuloendothelial blockage induced by this rare earth metal chloride is due to defects in the surface attachment and in the engulfment phases of phagocytosis.
Abstract: The cellular basis of Kupffer-cell phagocytosis blockade induced by gadolinium chloride was studied in rats Investigations with heterologous erythrocytes labelled with 51Cr show that the gadolinium chloride-induced reticuloendothelial blockade is due to the depressed phagocytic activity of the Kupffer cells Our light-microscopic studies indicate that, as a result of the action of gadolinium chloride, the impaired Kupffer-cell phagocytosis is observed not only in normal, non-activated Kupffer cells, but also in those activated with a reticuloendothelial stimulant, Zymosan Our electron-microscopic investigations suggest that the failure of the Kupffer cells to incorporate carbon during the reticuloendothelial blockage induced by this rare earth metal chloride is due to defects in the surface attachment and in the engulfment phases of phagocytosis

138 citations


Journal ArticleDOI
TL;DR: It is proved that for d > 2, almost every graph of order n satisfies n ((log 2 n ) 1/2 +4) -1 ccl( G ) ⩽ n ( Log 2 n - d log 2 log 2 n ), which implies the statement in the title.

136 citations


Book ChapterDOI
TL;DR: In this article, a new method for the dealumination of faujasite-type zeolites is presented, which can be dealuminated by reaction with silicon tetrachloride without collapse of the crystal structure.
Abstract: Publisher Summary This chapter presents a new method for the dealumination of faujasite-type zeolites. Y zeolites can be dealuminated by reaction with silicon tetrachloride without collapse of the crystal structure. X-ray diffraction pattern and mid-infrared spectra point to a high degree of ordering in the framework of the dealuminated products, and the adsorption of hydrocarbons reveals no significant differences in the pore system compared with Na–Y. In contrast to the described new dealumination method, dealumination under hydrothermal conditions changes the pore system and the structure of the framework to a certain degree. Y zeolites dealuminated by silicon tetrachloride may offer new application possibilities as hydrophobic adsorbents. It can be expected that the hydrogen form of partly dealuminated zeolite Y is an active catalyst for hydrocarbon reactions with excellent thermal and hydrothermal stability.

134 citations


Journal ArticleDOI
TL;DR: Introduction of genes from the irradiated parsley nuclei into the carrot genome was shown by the correction of the albino defect and by the appearance of parsley isoenzymes in selected green tissues and plants.
Abstract: In attempts at somatic transfer of plant genomes of reduced size, X-irradiated leaf protoplasts of parsley (Petroselinum hortense, 2n=22) were fused with cell culture protoplasts of a nuclear albino mutant of carrot (Daucus carota, 2n=18). Introduction of genes from the irradiated parsley nuclei into the carrot genome was shown by the correction of the albino defect and by the appearance of parsley isoenzymes in selected green tissues and plants. The cytological studies provided information on significant deviation from the amphidiploid chromosome number. The high frequency of cells with 2n=19, 2n=38 and regeneration of plants with 2n=19 chromosomes can indicate that the elimination of parsley chromosomes is incomplete. A correlation was found between the lethality of selected tissues and differentiated or undifferentiated stages of the cells.

Journal ArticleDOI
TL;DR: In this paper, the structure of s-cyclodextrin was proved by gas-liquid chromatographic and 1H-NMR and 13C NMR spectroscopic investigations.
Abstract: The methylated analogues of s-cyclodextrin dissolve in cold water 10 – 20 times better than s-cyclodextrin itself, however, quite unusually on heating they crystallize from the solution. The structure of heptakis-(2,6-di-O-methyl)- and heptakis-(2,3,6-tri-O-methyl)-s-cyclodextrin was proved by gas-liquid chromatographic and 1H-NMR and 13C-NMR spectroscopic investigations. The corresponding model compounds were synthetized and, according to 13C-NMR spectroscopic investigations, a part of the so far published NMR assignations have to be corrected.

Journal ArticleDOI
TL;DR: In this paper, it was shown that each square centrohermitian matrix is similar to a real (pure imaginary) matrix with real entries, and that skew-centro-hermitians are similar to real-valued centro-symmetric matrix.

Journal ArticleDOI
01 Aug 1980-Gene
TL;DR: The gene coding for the sequence-specific modification methylase methM .


Journal ArticleDOI
01 Mar 1980-Networks
TL;DR: It is proved that with the exception of C4, there are no graphs of diameter 2, of maximum degree d, and with d2 vertices.
Abstract: It is well known that there are at most four Moore graphs of diameter 2, i.e., graphs of diameter 2, maximum degree d, and d2 + 1 vertices. The purpose of this paper is to prove that with the exception of C4, there are no graphs of diameter 2, of maximum degree d, and with d2 vertices.

Journal ArticleDOI
TL;DR: In this paper, a method of confidence intervals for copolymerization reactivity ratios determined by the linear Kelen-Tudős method is described, both for low and high conversions.
Abstract: Calculation method of confidence intervals for copolymerization reactivity ratios determined by the linear Kelen-Tudős method is described, both for low and high conversions. The intervals as well as the confidence regions were compared with those obtained using non-linear estimation. No considerable deviations were found either in the parameter values or in their errors.

Journal ArticleDOI
TL;DR: Computer algorithms are presented for evaluating the multidimensional normal distribution function by Monte Carlo techniques and their applications in stochastic programming models and in multivariate statistical problems.
Abstract: Computer algorithms are presented for evaluating the multidimensional normal distribution function by Monte Carlo techniques. The computation of such probabilities is frequently required in stochastic programming models and in multivariate statistical problems. Using a medium size computer, three significant digits can be obtained up to ten dimensions in five seconds, up to twenty dimensions in one minute and up to fifty dimensions in ten minutes. Results of the detailed computer experiences are also reported together with some numerical examples.

Journal ArticleDOI
TL;DR: It is found that the protonated guanidino group is the main reacting species in acidic solutions; at neutral–alkaline pH, however, reaction of the unprotonated form is predominant and the lower pKa of arginine leads to its hyperreactivity toward the different α-dicarbonyl reagents.
Abstract: Factors affecting the reactivity of arginyl side-chains of proteins toward α-dicarbonyl reagents have been considered. The reaction of the guanidino group with different α-dicarbonyl compounds is shown to proceed by a common pathway, the rate-limiting step being essentially identical with an amine–carbonyl addition reaction. We found that the protonated guanidino group is the main reacting species in acidic solutions; at neutral–alkaline pH, however, reaction of the unprotonated form is predominant. Under the conditions usually employed for the modification of enzymes only the pathway utilizing the unprotonated form of arginine is of importance, the reactivity of individual arginyl side-chains toward α-dicarbonyls is primarily determined by the pka value of the guanidinium groups. It is proposed that the pKa value of arginyl residues of anion binding sites is lower than that of other arginyl residues, due to the strong positive electric potential of the anion binding sites. The lower pKa of arginine leads to its hyperreactivity toward the different α-dicarbonyl reagents, providing an explanation for the general observation that α-dicarbonyl reagents are remarkably selective for arginyl residues involved in anion binding. The various predictions of our proposition are considered and tested experimentally on the arginine residue of the high-affinity anion binding site of rabbit muscle aldolase.

Journal ArticleDOI
TL;DR: Six children in an inbred isolate (a gypsy colony) were found to have a syndrome of reduplication of the big toes, supernumerary fingers on the hands, cleft lip/palate or lingual nodule, and somatic and psychomotor retardation.
Abstract: Six children in an inbred isolate (a gypsy colony) were found to have a syndrome of reduplication of the big toes, supernumerary fingers on the hands, cleft lip/palate or lingual nodule, and somatic and psychomotor retardation. Other features sometimes present were absence of olfactory bulbs and tracts, cryptorchidism, inguinal hernia, and congenital heart disease. The disorder has overlapping features with several previously delineated syndromes, but is most similar to the anomalies of trisomy 13 Mand ohr's syndrome. Our patients had a normal karyotype. The mode of inheritance of this lethal genetic syndrome is probably autosomal recessive.

Journal ArticleDOI
TL;DR: This paper proves special cases of the following conjecture: for any fixed tree T there exists a natural number f = f (T) to that every triangle-free graph of chromaticnumber f(T) contains T as an induced subgraph.

Journal ArticleDOI
TL;DR: Universally attainable error exponents for broadcast channels with degraded message sets are obtained using a technique which generalizes that introduced by Csiszar, Korner, and Martron for the ordinary channel.
Abstract: Universally attainable error exponents for broadcast channels with degraded message sets are obtained using a technique which generalizes that introduced by Csiszar, Korner, and Martron for the ordinary channel. Lower and upper bounds to the error probabilities over a single broadcast channel are also given.

Journal ArticleDOI
TL;DR: In this paper, it was shown that every finite lattice is isomorphic to the congruence lattice of a finite algebra if and only if every finite algebraic lattice can be characterized by an interval in the subgroup lattice.
Abstract: I t is well-known that every algebraic lattice is isomorphic to the congruence lattice of an algebra. In this pape r we are interested in the prob lem of characterizing the finite lattices, which are isomorphic to the congruence lattices of finite algebras. We are not able to settle the prob lem if every finite lattice is isomorphic to the congruence lattice of a finite algebra (cf. [1], Problem 13). Our main result shows that this problem is related to the prob lem to characterize intervals in subgroup lattices of finite groups. Namely, every finite lattice is isomorphic to the congruence lattice of a finite algebra if and only if every finite lattice is isomorphic to an interval in the subgroup lattice of a finite group.

Journal ArticleDOI
TL;DR: In this article, the L X-ray production and subshell ionisation cross sections of gold have been measured by proton, alpha particle, carbon, nitrogen and oxygen bombardment in the energy range 0.4-3.4 MeV.
Abstract: The L X-ray production and subshell ionisation cross sections of gold have been measured by proton, alpha particle, carbon, nitrogen and oxygen bombardment in the energy range 0.4-3.4 MeV. These data are compared with the predictions of the plane-wave Born approximation including the binding energy, Coulomb deflection and relativistic corrections. Satisfactory agreement has been obtained between theory and experiment except for the cross sections of the L2-subshell ionisation induced by heavy ions (12C, 14N, 16O). The theory underestimates these cross sections by almost one order of magnitude.



Journal ArticleDOI
TL;DR: It is suggested that colostral antibodies, raised against the crude K99 extract vaccine, exerted a protective effect on newborn calves against the challenge enterotoxigenic E. coli O101:K99+, Ent+ strain.
Abstract: Pregnant cows and heifers were vaccinated with a crude K99 extract prepared from an Escherichia coli K-12, K99 strain A similar group, injected with an extract prepared from the K-12 parent strain, served as a control Eleven calves were born to both groups and challenged orally with a mean of 16 x 10(11) bacteria of enterotoxic E coli B41 (O101:K99+, ST+) at the time of first colostrum uptake (1 to 7 h after birth) As a result of challenge, no death occurred in the vaccine group, but four calves died in the control group Six calves in the vaccine group and all calves in the control group developed diarrhea Colostral anti-O101 titers were very similar in both groups Anti-K99 titers of colostral samples from the vaccinated dams were, however, significantly higher as compared to those of the controls It is suggested that colostral antibodies, raised against the crude K99 extract vaccine, exerted a protective effect on newborn calves against the challenge enterotoxigenic E coli O101:K99+, Ent+ strain

Journal ArticleDOI
TL;DR: The synthesis of salutaridine derivatives via phenolic coupling on norreticuline derivatives can be performed in improved yields, using non-metallic oxidizing agents as discussed by the authors.


Journal ArticleDOI
TL;DR: In this paper, the first neighbour model was modified by dropping the assumption that the structure of the free solvent is identical with that of the pure solvent, and the modified model, FNM2, reproduces the experimental X-ray structure functions of alkali chloride solutions quite well and enables the study of perturbed solvent-solvent interactions.
Abstract: Abstract The first neighbour model, FNM, used frequently for the description of hydration has been modified by dropping the assumption that the structure of the \"free\" solvent is identical with that of the pure solvent. The modified model, FNM2, reproduces the experimental X-ray structure functions of alkali chloride solutions quite well and enables the study of perturbed solvent-solvent interactions. The refined structural parameters reasonably indicate the dependence of the hydration of the alkali cations on their radius and concentration. The hydration of Cl- has been found to be almost independent of both concentration and the type of counter cation. The model assumes regular symmetry for the first neighbour coordination sphere, but the high rms deviations of the water-water distances within the shells of the aggregates indicate con-siderable individual asymmetries. A further modification of the FNM will be discussed in a following paper.