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Showing papers by "Charles University in Prague published in 1982"


Journal ArticleDOI
TL;DR: In this paper, an asymptotic procedure for the computation of wave fields in two-dimensional laterally inhomogeneous media is proposed based on the simulation of the wave field by a system of Gaussian beams.
Abstract: Summary. An asymptotic procedure for the computation of wave fields in two-dimensional laterally inhomogeneous media is proposed. It is based on the simulation of the wave field by a system of Gaussian beams. Each beam is continued independently through an arbitrary inhomogeneous structure. The complete wave field at a receiver is then obtained as an integral superposition of all Gaussian beams arriving in some neighbourhood of the receiver. The corresponding integral formula is valid even in various singular regions where the ray method fails (the vicinity of caustic, critical point, etc.). Numerical examples are given.

545 citations


Journal ArticleDOI
TL;DR: There is no causal relationship between species diversity and both kinds of stability, and the results imply the validity of Gleasonian, population-centered explanation of community phenomena.
Abstract: The essence of the contradiction between traditional ecological complexity-stability hypothesis and recent theoretical results is clarified. The distinction between resilience and resistance is stressed. The possibilities of field verification of May's model are discussed. No satisfactory method for estimation of connectance and mean interaction strength in plant communities has been found. Relation between these parameters and stability in real communities remains an open question. The relation between connectance and stability (resilience) in purely competitive model communities is more complicated than May's rule predicts. The certain value of connectance having been achieved, stability increases with increasing connectance. We assessed the positive relation between species diversity and resistance, and negative relation between species diversity and resilience in plant communities during old-field succession in xeric habitat. But there is no causal relationship between species diversity and both kinds of stability. Resistance and resilience of the plant communities studied were determined primarily by life history strategies of constituent species. The results are interpreted in terms of Grimes' life history strategies and imply the validity of Gleasonian, population-centered explanation of community phenomena.

250 citations


Journal ArticleDOI
TL;DR: In this article, a finite analogue of the Birkhoff variety theorem is proved: a non-void class of finite algebras of a finite type τ is closed under the formation of finite products, subalgesas and homomorphic images if and only if it is definable by equations for implicit operations, that is, roughly speaking, operations which are not necessarily induced by τ-terms but which are compatible with all homomorphisms.
Abstract: A finite analogue of the Birkhoff variety theorem is proved: a non-void class of finite algebras of a finite type τ is closed under the formation of finite products, subalgebras and homomorphic images if and only if it is definable by equations for implicit operations, that is, roughly speaking, operations which are not necessarily induced by τ-terms but which are compatible with all homomorphisms. It is well-known that explicit operations (those induced by τ-terms) do not suffice for such an equational description. Topological aspects of implicit operations are considered. Various examples are given.

247 citations


Journal ArticleDOI
TL;DR: U-Pb zircon and Rb-Sr whole-rock analyses from various gneisses and plutonie rocks of the Moldanubian and Moravo-Silesian zones and the stable foreland of the Hercynian (Variscan) orogenic belt indicate that most of the crust in Central Europe was first formed during the Cadomian orogeny which straddles the Precambrian-Cambrian boundary.
Abstract: U–Pb zircon and Rb–Sr whole-rock analyses from various gneisses and plutonie rocks of the Moldanubian and Moravo-Silesian zones and the stable foreland of the Hercynian (Variscan) orogenic belt indicate that most of the crust in Central Europe was first formed during the Cadomian orogeny which straddles the Precambrian–Cambrian boundary. Zircons, however, have a memory of older ages which correspond with those of events known in Fennoscandia. The new radiometrie data are consistent with the stratigraphie record in that they do not provide any evidence for a major early Palaeozoic tectonothermal event between the Cadomian and Hercynian orogenies.Granulites from two localities in the Moldanubian zone yield U–Pb zircon ages of 345 ± 5 Ma; discordant zircon data points indicate that the granulite facies metamorphism was not of long duration. Tectonic units containing these high grade rocks were emplaced amongst amphibolite facies rocks during an event of widespread shearing which has been dated at 341 ± 4 Ma on the basis of a lower U–Pb zircon intercept age from one of the sheared gneisses and 338 ± 3 Ma U–Pb ages from monazites. Rb–Sr muscovite ages of 331 ± 5 Ma from pegmatites axial planar to asymmetrical folds date the last stage of SE-directed simple shear. A Rb–Sr whole-rock isochron of 331 ± 4 Ma from a principal magmatic type of the Central Bohemian pluton confirms the field evidence that the large NE-trending plutons of the Moldanubian zone were emplaced during a late stage of the deformation. The strong disturbance of the U–Pb zircon isotopic system in the sheared gneisses suggests U loss while a high U/Th ratio in monazite from one of these tectonised rocks suggests the simultaneous passage of hydrothermal fluids. Thus a crustal source is indicated for the uranium deposits of the Moldanubian zone.Critical to any plate tectonic model for the development of the Middle European Hercynides was the existence of an ocean in Early Devonian times which separated a North European continent from a South European continent(s). The northward movement of the South European continent over a shallowly-dipping subduction zone and subsequent continental collision can explain the high T–low P metamorphism and the imbricated tectonic style of the Moldanubian zone and adjacent Moravo-Silesian zone along the southeastern Hercynian foreland. The temporal separation of granulites and granites implies distinct conditions of formation and it has been suggested that the plutonism, following on from the imbrication of the Cadomian crust, was initiated by the subduction of wet oceanic sediments.

246 citations



Journal ArticleDOI
TL;DR: In this article, the advantages of using the selective properties of cyclodextrins for chromatographic separations and the possibilities of studying inclusion processes of different cyclodeextrins with various types of substances, in the liquid as well as in the gaseous phase, are demonstrated and discussed.

125 citations


Journal ArticleDOI
TL;DR: A simple micromethod for testing human blood leukocyte phagocytosis employing synthetic hydrophilic particles based on 2-hydroxyethylmethacrylate is described and was found suitable for routine testing in both clinical and laboratory practice.

112 citations


Proceedings ArticleDOI
05 Jul 1982
TL;DR: The hierarchy of salience is argued to be a basic component of a mechanism serving for the identification of reference, the description of which is a necessary prerequisite of an automatic understanding of connected texts.
Abstract: The elements of the stock of knowledge shared by the speaker and the hearer change their salience, in the sense of being immediately accessible in the hearer's memory. The hierarchy of salience is argued to be a basic component of a mechanism serving for the identification of reference. Some of the regularities of this mechanism are discussed, the description of which is a necessary prerequisite of an automatic understanding of connected texts.

60 citations


Journal ArticleDOI
TL;DR: In this article, a mixed formulation of the Signorini problem with normal forces on the contact surface is derived, making use of the duality approach, which allows us to approximate independently the displacement field in the body and the normal and 99 0022-247x/82/030099-24eo2.

56 citations


Journal ArticleDOI
TL;DR: In this article, an integral expansion which expresses a plane monochromatic wave as a superposition of Gaussian beams is found, which can be used to solve many wave propagation problems in complicated structures, including laterally inhomogeneous media with curved interfaces.
Abstract: An integral expansion which expresses a plane monochromatic wave as a superposition of Gaussian beams is found. The expansion can be used to solve many wave propagation problems in complicated structures, including laterally inhomogeneous media with curved interfaces.

54 citations


Journal ArticleDOI
TL;DR: The conclusion is that camelpox, although economically important to herdsmen, is of no epidemiological importance to man in the area investigated and it is suggested that an immunological survey be conducted to determine the degree of pathogenicity of camelpox in man.

Journal ArticleDOI
TL;DR: In this article, the formation and properties of inclusion compounds of α- and β-cyclodextrin were studied in a gas-solid chromatographic system, and the results of chromatogram measurements were correlated with polarizability and polarity data for the sorbate molecules, and interpreted in terms of the possible interactions involved.

Journal ArticleDOI
01 Feb 1982-Talanta
TL;DR: The stability constants of the MX(+) complexes were determined by potentiometry with fluoride and chloride ion-selective electrodes and the appropriate thermodynamic functions (DeltaH, DeltaS, and DeltaG) were calculated.

Journal ArticleDOI
TL;DR: In this paper, five derivatives of polyaspartamide were used as macromolecular models to study the effect of chemical structure of macromoles on their renal excretion and retention.
Abstract: Five derivatives of polyaspartamide were used as macromolecular models to study the effect of chemical structure of macromolecules on their renal excretion and retention. The parent polymer was formed solely by N(2-hydroxyethyl)aspartamide units (I) and in its derivatives about 20% of 2-hydroxyethyl groups were randomly replaced by either n-butyl- (II), 2(4-hydroxyphenyl)ethyl- (III), N-dimethylamino propyl- (IV) or the aspartamide unit was modified to free aspartic acid carboxyl (V). The rate of clearance from the serum, the deposition in the kidney tissue in comparison with the deposition in reticuloendothelial system organs — liver and spleen, as well as tissue and cellular localisation of deposites were studied on rabbits and mice taking advantage of fluorescence labelling. The clearance of macromolecular models from the serum compartment by the glomerular filtration is mainly molecular weight controlled, while the retention of macromolecules possessing the same molecular weight by the kidney tubular epithelium is strongly affected by chemical modification. About thirty and hundred times higher retentions due to reabsorption in proximal rubule were found with macromolecular models II and III respectively.

Journal ArticleDOI
TL;DR: The hypothesis that the differences in maximal aerobic power between the Norwegian and German children are due to differences in growth and maturation with little additional effects of other factors is tested.
Abstract: In a recent paper, Rutenfranz et al. (1981) studied the development of physical performance capacity relative to body composition during childhood and adolescence in representative samples of Norwegian and German schoolchildren. In this longitudinal investigation, the rate of growth in body size and composition relative to age was identical in the two cohorts of children and followed closely the trend that has been assessed for North-Europeans in general (Eveleth and Tanner 1976). However, compared on the basis of chronological age, the Norwegian children averaged higher in maximal aerobic power, which was observed in girls as well as in boys at all comparable ages. The purpose of this paper was to examine the maximal aerobic power and its rate of change as a function of maturation and body growth in order to test the hypothesis that the differences in maximal aerobic power between the Norwegian and German children are due to differences in growth and maturation with little additional effects of other factors.


Journal ArticleDOI
TL;DR: The results indicate that earlier investigations of the distribution of ChAT in the heart provided a basically correct picture although the contribution of CarAT to the synthesis of ACh measured had not been excluded, and confirm that ChAT is present throughout the heart, including the apical parts of the ventricles.
Abstract: The distribution of choline acetyltransferase (ChAT, EC 2.3.1.6) in the heart of adult rats has been reinvestigated in view of recent discoveries that acetylcholine (ACh) can be synthesized not only by ChAT, but also by carnitine acetyltransferase (CarAT, EC 2.3.1.7) and that it is possible to distinguish between the ACh-synthesizing activity of ChAT in intramuscular nerves and the CarAT-mediated extraneural synthesis of ACh by means of bromoacetylcholine (BrACh), a specific inhibitor of ChAT. BrACh (0.002 mmol/l) has been found to inhibit the synthesis of ACh in the atria by 66–85% and in the ventricles by only 19–29%. Bromoacetylcarnitine (BrACar, 0.02 mmol/l), an inhibitor of CarAT, inhibited the synthesis of ACh in the atria by 34% and in the ventricles by 74–80%. These findings indicate that ChAT is responsible for most of the synthesis of ACh observed in the homogenates of the atria; in the ventricles, it catalyses only a minor portion of the total ACh synthesis observed. In the investigation of the regional distribution of ChAT in the heart, the BrACh-sensitive part of ACh synthesis was taken as the measure of ChAT activity. The highest activity of ChAT (nmol ACh synthesized ·g−1·h−1) was found in the region of the sinoatrial aode (1775); it decreased in the order: interatrial septum (781) > rest of the right atrium (712) > left atrium (416) > basal part of the right ventricle (366) > apical part of the right ventricle (250) > inter-ventricular septum (239) > basal and apical part of the left ventricle (208 and 205). The results indicate that earlier investigations of the distribution of ChAT in the heart provided a basically correct picture although the contribution of CarAT to the synthesis of ACh measured had not been excluded, and confirm that ChAT is present throughout the heart, including the apical parts of the ventricles. However, the sino-atrio-ventricular gradient of ChAT distribution is steeper when the contribution of CarAT to the synthesis of ACh is excluded.

Journal ArticleDOI
TL;DR: A new method is proposed for reliability parameter estimation of elements and subsystems forming biological systems and could bring new information regarding the causes of declining reliability of biological systems during their aging.

Journal ArticleDOI
TL;DR: In this paper, the thermal decomposition of Te(OH)6, CO(NH2)2 and the adduct Te( OH)6 in air and in an inert atmosphere were studied using TG, DTG, DTA and GC methods in the interval between laboratory temperature and 750°.
Abstract: The thermal decompositions of Te(OH)6, CO(NH2)2 and the adduct Te(OH)6. 2 CO(NH2)2 in air and in an inert atmosphere were studied using TG, DTG, DTA and GC methods in the interval between laboratory temperature and 750°. The first gaseous product of the decomposition of urea is water vapour; the decomposition yields first cyanamide, and then biuret in four steps. The adduct is primarily decomposed to diammonium metatellurate and urea, with liberation of H2O and CO2. Diammonium metatellurate is decomposed toα-TeO3 as intermediate-product.

Journal ArticleDOI
TL;DR: Hladik et al. as mentioned in this paper showed that fraction III is an oligomeric form of the chlorophyll-protein complex of fraction II, whereas fraction III contains specifically oriented and space-fixed molecules of carotenoids.

Journal ArticleDOI
TL;DR: HoCu2 shows a Curie-Weiss susceptibility above 15 K and the paramagnetic moment is (10.1 ± 0.1) μB/H0 and (4 ± 2) K, respectively as discussed by the authors.
Abstract: HoCu2 shows a Curie-Weiss susceptibility above 15 K. The paramagnetic moment and the paramagnetic Curie temperture is (10.1 ± 0.1) μB/H0 and (4 ± 2) K, respectively. Two cusps (at about 7 and 10 K) are seen in the magnetization versus temperature curve. These cusps reflect a change of the magnetic structure and the Neel temperature. The influence of conduction electron scattering on the localized 4f moments is estimated for the resistivity and the thermopower. Neutron diffraction measurements show that the antiferromagnetic structure is incommensurate with the crystal lattice. HoCu2 zeigt oberhalb 15 K eine Curie-Weiss-Suszeptibilitat. Das paramagnetische Moment betragt (10,1 ± 0,1) μB/H0, und die paramagnetische Curie-Temperatur ist (4 ± 2) K. Die Temperaturabhangigkeit der Magnetisierung zeigt bei etwa 7 und 10 K einen Knick in ihrem Verlauf. Diese Anomalien werden von einer Anderung in der magnetischen Struktur bzw. der Neel-Temperatur verursacht. Der Einflus der Streuprozesse der Leitungselektronen an den 4f-Momenten auf den elektrischen Widerstand und die Thermokraft wird abgeschatzt. Neutronenbeugungsmessungen zeigen, das unterhalb 7 K die antiferromagnetische Struktur und die kristallographische Struktur inkommensurabel sind.

Journal ArticleDOI
TL;DR: It is suggested that FPSDs might represent synaptic precursors perhaps induced to form as a response to loss (possibly age-dependent loss) of synaptic contacts on a neuron and that the SSCs are somehow involved in maintaining the FPSDs and/or preparing them for innervation by adjacent axon terminals to form new synaptic contacts.
Abstract: Samples of cerebral cortex (parietal and occipital) and thalamic nuclei (ventrobasal, posterolateral, dorsal lateral geniculate) from normal, adult, aldehyde perfusion fixed mice and rats were examined by electron microscopy for the presence of free postsynaptic-like densities (FPSDs). FPSDs are plaques of intracellular paramembranous electron-dense material, ultrastructurally indistinguishable from postsynaptic densities, but not aligned with a presynaptic specialization. In a systematic survey of the neuropil around 6000 neuronal perikarya, 250 FPSDs were encountered. Almost all of these were within dendritic spines and shafts and about 90% of them were apposed by a neuronal perikaryon, the remainder by a dendritic shaft. Inevery case a subsurface cistern (SSC) was present in the cell body or dendrite apposed to the FPSD, and was flattened along the extent of the FPSD. In none of the material were the FPSDs associated, even remotely, with degenerating elements, suggesting that they are not formed by degeneration of presynaptic boutons. The incidence of FPSD-SSC complexes was higher in thalamus than in cerebral cortex which, together with previous observations indicating their absence from normal cerebellar cortex, suggests significant regional variations in distribution. It is suggested that FPSDs might represent synaptic precursors perhaps induced to form as a response to loss (possibly age-dependent loss) of synaptic contacts on a neuron and that the SSCs are somehow involved in maintaining the FPSDs and/or preparing them for innervation by adjacent axon terminals to form new synaptic contacts.

Journal ArticleDOI
TL;DR: The peripheral blood chromosomes of eight patients with retinoblastoma were examined and an interstitial deletion of 13q was found, raising the possibility of maternal origin of the 13q deletion in a child.
Abstract: We examined the peripheral blood chromosomes of eight patients with retinoblastoma. In two of them an interstitial deletion of 13q was found. The breakpoints were determined as follows: case 1, 13q12→21; case 2, 13q12→31. In both cases, band 13q14 was deleted. In case 2 the lymphocytes of the mother showed the identical interstitial 13q deletion in 3 of 100 mitoses, thus raising the possibility of maternal origin of the 13q deletion in a child. In one patient, retinoblastoma was unilateral; in the other, bilateral. Both patients were mentally retarded.

Journal ArticleDOI
TL;DR: Using laser light scattering a rapid method for estimating relative counts of less deformable erythrocytes in blood samples was developed based on comparison of light scattering from blood cells deformed in defined shear stress and blood cells at rest.
Abstract: Using laser light scattering a rapid method for estimating relative counts of less deformable erythrocytes in blood samples was developed. The procedure is based on comparison of light scattering from blood cells deformed in defined shear stress and blood cells at rest, respectively.

Journal ArticleDOI
TL;DR: Methods which overcome the difficulties of both the sensitivity of the S phase CFU‐s to hydroxyurea and their in the [3H] thymidine suicide technique vary as the cells pass through the S phases have been used.
Abstract: Hydroxyurea induces profound changes in the pluripotential haemopoietic stem cell (CFU-s) kinetics. The main feature of these changes is a synchronous entry of resting G0 CFU-s into the cell cycle. The analysis of the passage of the CFU-s cohort through the cell cycle has been largely based on the examination of the fraction of CFU-s which synthesize DNA in the S phase of the cell cycle. This analysis has, however, been hampered by the fact that both the sensitivity of the S phase CFU-s to hydroxyurea and their sensitivity in the [3H]thymidine suicide technique vary as the cells pass through the S phase. Methods which overcome these difficulties have been used in the experiments presented in this paper. It was demonstrated that hydroxyurea kills only about 80% of the S phase CFU-s. The sensitivity to hydroxyurea gradually decreases as the cells approach the middle part of the S phase and increases again as the cells enter the late portions of the S phase. The degree of CFU-s synchrony at the point of entry into and exit from, the S phase has been established. Mathematical analysis of the available data suggests that CFU-s pass through the S phase with a mean transit time of 4.79 hr (standard deviation, 1.45 hr). Hydroxyurea, administered in vivo, blocks CFU-s in the late G1 phase. The duration of this G1-S block, induced by a dose of 1000 mg of hydroxyurea per kg body weight, is approximately 2 hr. The CFU-s in the middle of the S phase, which survive hydroxyurea administration, are also blocked in their passage through the S phase. These cells, however, seem to finish the S phase with a delay of approximately 2 hr.


Journal ArticleDOI
TL;DR: In this article, the course of the transformation of synthetic γ-FeOOH (lepidocrocite) samples, prepared by different methods, was investigated and the effect of a preliminary heat treatment of the initial material on the product phase composition and morphology was studied.
Abstract: The course of the transformation of synthetic γ-FeOOH (lepidocrocite) samples, prepared by different methods was investigated and the effect of a preliminary heat treatment of the initial material on the product phase composition and morphology studied. Both the goethite-tohematite ratio and the particle size of the products depend on the preparation method and on the preliminary heat treatment of the initial lepidocrocite. The results are discussed in terms of the dissolution of the less stable lepidocrocite followed by the crystallization of the more stable phases α-FeOOH and α-Fe2O3 from the solution. The final product phase composition and the particle size are affected considerably by a presence of goethite and/or hematite germs in the initial γ-FeOOH. Umwandlung von synthetischem γ-FeOOH (Lepidocrocit) in wasrigen Losungen von Eisen(II)-sulfat Der Verlauf der Umwandlung von synthetischem, nach verschiedenen Methoden dargestelltem γ-FeOOH (Lepidocrocit) in wasrigen Losungen von FeSO4 und der Einflus einer thermischen Vorbehandlung auf die Phasenzusammensetzung und Morphologie der Produktpartikel wurde untersucht. Die Gehalte an α-FeOOH und α-Fe2O3 sowie die Partikelgrosen der Produkte hangen sowohl vom Praparationsweg des Ausgangslepidocrocits wie auch von der thermischen Vorbehandlung ab. Die Ergebnisse werden als Auflosung des weniger stabilen Lepidocrocits und Kristallisation der stabileren Phasen α-FeOOH und α-Fe2O3 aus der Losung diskutiert. Die endliche Zusammensetzung der Produkte sowie ihre Partikelgrosen werden besonders durch die Anwesenheit von Keimen dieser Phasen im Ausgangs-γ-FeOOH beeinflust.

Journal ArticleDOI
TL;DR: Five genera of hepatics in Africa, IsotachisMitt.
Abstract: The present study deals with five genera of hepatics in Africa, IsotachisMitt., Anastrophyllum (Spruce) Steph., TritomariaSchiffn. ex Loeske, Gymnocoleopsis (Schust.) Schust. and Lophozia (Dum.) Dum. All African populations of the genus IsotachisMitt. are considered to be one species, I. aubertii (Schwaegr.) Mitt. Four species of Anastrophyllum (Spruce) Steph. (s.l.), A. auritum (Lehm.) Steph., A. piligerum (Nees) Spruce, A. subcomplicatum (Lehm. et Lindenb.) Steph. and A. minutum (Schreb.) Schust., and two species of TritomariaSchiffn. et Loeske, T. camerunensisS. Arnell and T. exsecta (Schrad.) Schiffn. ex Loeske occur in Africa. Gymmocoleopsis multiflora (Steph.) Schust. represents a genus and species hitherto unreported for the African flora. Finally, five Lophozia (Dum.) Dum. species, L. argentina (Steph.) Schust., L. capensisS. Arnell, L. decolorans (Limpr.) Steph., L. hedbergiiS. Arnell and L. tristaniana (S. Arnell) Vaňa, are reported from central and southern Africa; two of these (L. argentina (Steph.) Schust. and L. decolorans (Limpr.) Steph.) represent the first reports from Africa.

Journal ArticleDOI
TL;DR: The incrassatio frontoparietalis is a clearly delimited part of the frontopARietal, covering the gap or gaps in the dorsal wall of the endocranium, and is probably a good diagnostic character in frogs.
Abstract: The incrassatio frontoparietalis is a clearly delimited part ofthe frontoparietal, covering the gap or gaps in the dorsal wall of the endocranium. In frogs, this structure originates in very early ontogenetic stages, and keeps its shape without considerable changes till maturity. Therefore, it is probably a good diagnostic character. Moreover, it is presumed that this structure also is a good phylogenetic character, and its study based on an extensive recent and fossil material might contribute to our present knowledge of the frog phylogeny.

Journal ArticleDOI
TL;DR: The sexual development and sex life of 12 women with the Küstner-Rokitansky syndrome, in whom the developmental anomaly was corrected through surgery, were examined through structured interviews and by means of questionnaire.
Abstract: The sexual development and sex life of 12 women with the Kustner-Rokitansky syndrome, in whom the developmental anomaly (vaginal agenesis) was corrected through surgery, were examined through structured interviews and by means of questionnaires. The comparison group was 22 women who had regular menses and a functional sex life. All differences between the groups were statistically nonsignificant. Only in one questionnaire was there a slight trend toward retarded heterosexual development in the patient sample.