Showing papers by "Charles University in Prague published in 1988"
456 citations
TL;DR: Using β-cyclodextrin and heptakis(2,6-di-O-methyl)-β-cyclodextrin as additives to the leading electrolyte in isotachophoresis, the complete chiral resolution of pseudoephedrine antipodes was achieved, but ephedrine enantiomers were not separated.
123 citations
TL;DR: A new distribution function containing the Altarelli-Parisi quark distribution function as a special case is obtained, which induces a relation between the AP- and the extended BL-kernels, and the consistency of the existing two-loop results is confirmed.
107 citations
TL;DR: In this article, the microhardness, the phase and chemical composition, the texture, strains and macrostresses in non-stoichiometric TiNx films as a function of ON2 are presented.
80 citations
TL;DR: In this article, the toxicity of poly(2-hydroxyethyl methacrylate) [poly(HEMA)] hydrogel spherical particles, prepared by radical suspension polymerization and designed for endovascular occlusion, was studied in vitro on cell cultures.
79 citations
TL;DR: In this paper, the hardness of the hardest TiN x coatings was investigated on steel substrates with an average deposition rate ranging from 0.1 to 0.5 μm min -1.
77 citations
TL;DR: The chromatographic behaviour of eighteen s-triazine derivatives has been studied in a reversed-phase system with a Separon SIC 18 stationary phase and a mobile phase of aqueous sodium dihydrogenphosphate and methanol and the dependences of the capacity factors on the meethanol content, the pH and the ionic strength have been obtained.
74 citations
TL;DR: It was concluded from this second study that the HR break point level coincides with Tvent, the point where HR departs from linearity in an incremental exercise test may be employed as a predictor of the ventilatory threshold (Tvent).
Abstract: In order to describe the kinetics of the reaction of the heart rate (HR) to the onset of exercise of constant intensity, the half‐time (t 1/2) of HR can be used. First in a study of exercise of intensity corresponding to 2 W kg‐1 on a cycle ergometer, the t 1/2 in 15 trained male rowers and 11 untrained male students was determined. In the trained subjects t 1/2 was smaller than in untrained students, mean (±s.d.) values being 24.10 (±3.36) s and 47.12 (±4.08) s respectively. In both groups t 1/2 was positively correlated with resting HR, r=0.774 and 0.846 and negatively correlated with maximal oxygen uptake (VO2max), r= ‐0.728 and ‐0.871 respectively (P<0.01). The regulation of HR in the transition range was concluded to be very similar to the regulation of VO2 and energy requirements. The second part of this work was concerned with responses to graded exercise. The linearity of the HR‐exercise intensity relationship is maintained up to a submaximal exercise intensity beyond which the increase i...
65 citations
TL;DR: The Cd 2+ ions inhibit ribulose-1,5-biphosphate carboxylase and the role of the Cd2+-induced inhibition of RuBPC in the mechanism of a C d 2+ toxicity on photosynthesis is discussed.
59 citations
59 citations
TL;DR: The mechanism of amperometric detection with a copper electrode has been studied with four amino-acids in four different carrier liquids containing aqueous buffer and methanol and it is concluded that the response is produced by complexation of the test substances with cupric ions in the outer, porous layer of the passivating film, with formation of CuL(+) species.
TL;DR: In this article, a general tendency of the lattice parameters to decrease with increasing layer thickness was found together with their systematic dependence on the orientation of grains in the coatings, which is explained by a gradual improvement in the structure of the layers with increasing thickness and by the heterogeneous nature of the structure.
Journal Article•
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TL;DR: A complexity theory based on the concept of the graph instead of the Boolean function is developed and its relation to the Boolean complexity is shown and some lower bounds to the complexity of explicitly given graphs are proved.
Abstract: SummaryWe develop a complexity theory based on the concept of the graph instead of the Boolean function. We show its relation to the Boolean complexity and prove some lower bounds to the complexity of explicitly given graphs.
TL;DR: The formation of the benzenediazonium ion evolved by oxidative splitting of the azo group of Sudan I by microsomal enzymes is proved and may be considered as the possible mechanism of the Sudan I activation to the ultimate carcinogen.
TL;DR: Isolated rat heart cells permeabilised by digitonin were examined as an experimental model to study heart bioenergetics and appeared to be functionally coupled with Oxidative phosphorylation and the ATPase activity of the cells.
Abstract: Isolated rat heart cells permeabilised by digitonin were examined as an experimental model to study heart bioenergetics. The cells showed good indices of oxidative phosphorylation (acceptor control ratio about 8 with pyruvate plus malate). The adenosine triphosphatase activity detected in the cells was high and was calcium dependent (optimum [free calcium] about 400 nmol.litre-1); magnesium was necessary for its full activity. Double reciprocal plot l/v vs 1/[free calcium] at physiological free calcium concentrations was linear, thus showing free calcium to be a substrate for the adenosine triphosphatase (Km for calcium about 149 nmol.litre-1). Double reciprocal plot 1/v vs 1/[ATP] was also linear, thus showing that the adenosine triphosphatase activity could be ascribed to a single enzyme. Oxidative phosphorylation and the ATPase activity of the cells appeared to be functionally coupled. This was manifested by apparent preference by oxidative phosphorylation for adenosine diphosphate supplied by the adenosine triphosphatase activity (Km 45 mumol.litre-1) to external adenosine diphosphate (Km 152 mumol.litre-1; p less than 0.02). Apparent preference by the adenosine triphosphatase activity for adenosine triphosphate supplied by mitochondria (Km 74 mumol.litre-1) to external adenosine triphosphate (Km 169 mumol.litre-1) was also manifested by a significant difference in Km values (p less than 0.05).
TL;DR: In this article, the autoregressive model Xt = bXt-1= Yt where 0 ≤ b < 1 and Ytare independent random variables with an exponential distribution is considered and moments of the stationary distribution of Xtare calculated and the distribution of an approximation to the maximum likelihood estimator for b is derived.
Abstract: We consider the autoregressive model Xt= bXt-1= Ytwhere 0 ≤ b < 1 and Ytare independent random variables with an exponential distribution. The moments of the stationary distribution of Xtare calculated and the distribution of an approximation to the maximum likelihood estimator for b is derived. The result is used for a construction of a confidence interval for b.
TL;DR: Antibody responses following the vaccination were generally low and were almost entirely limited to subjects suffering from HSV-2 lesions, and a majority of the patients exhibited improvement of their condition during the postvaccination period.
TL;DR: Non-enzymatic and enzymatically-driven lipid peroxidation processes were studied in rat liver nuclei and isolated nuclear membranes, by evaluating the formation of thiobarbituric acid-chromophore, free malondialdehyde, lipofuscin-like pigments, and the degradation of polyunsaturated fatty acids of the nuclear membrane lipids.
29 Aug 1988
TL;DR: It is shown that the problem of perfect code recognition is NP-complete even when resiricted to k-regular graphs or to 3-regular planar graphs, and in the case of trees and graphs of bounded tree-width an optimal ϑ(n) algorithm is developed.
Abstract: This paper linke to continuing research of the first author on codes in graphs [7–11]. Here codes are studied from the point of view of their computational complexity. It is shown that the problem of perfect code recognition is NP-complete even when resiricted to k-regular graphs (k≥4) or to 3-regular planar graphs. On the other hand in the case of trees and graphs of bounded tree-width an optimal ϑ(n) algorithm is developed. Some optimization problems are also investigated.
TL;DR: The high-performance liquid chromatographic (HPLC) analysis indicate that probably more than one radioactive adduct of activated Sudan I with deoxyguanosine is formed.
TL;DR: In this paper, the authors determined des courbes d'aimantation a 4,2 K and a 300 K sous champs magnetiques paralleles and perpendiculaires a l'axe C. Analyse en fonction de la temperature (0-500 K) du moment magnetique and des constantes d'anisotropie
Abstract: Determination des courbes d'aimantation a 4,2 K et a 300 K sous champs magnetiques paralleles et perpendiculaires a l'axe C. Analyse en fonction de la temperature (0-500 K) du moment magnetique et des constantes d'anisotropie
TL;DR: In this article, the existence of rigid interfaces as well as surface tension under appropriate conditions is proven and the properties of corresponding Gibbs states are investigated on a hypercubic lattice with spins attaining a finite number of values and finite-range interactions at low temperatures.
Abstract: Lattice models (on a hypercubic lattice of dimension larger than or equal to three) with spins attaining a finite number of values and finite-range interactions at low temperatures are considered. The existence of rigid interfaces as well as of surface tension under appropriate conditions is proven and the properties of corresponding Gibbs states are investigated.
TL;DR: In this paper, the authors discuss the electronic properties of actinide intermetallic compounds with a special emphasis on the magnetic behavior, and discuss the properties of binary and ternary compounds, including morphous and icosahedral compounds, and trans-thorium compounds with unoccupied 5f-electrons.
Abstract: Publisher Summary This chapter discusses the intermetallic compounds of actinides, and summarizes the electronic properties of actinide intermetallic compounds with a special emphasis on the magnetic behavior. The sequentially increasing occupation of 5f states dominates the electronic properties in the series of actinide elements. In the heavy actinides, on the other hand, the decrease of the energy due to the formation of a spin polarized (non-bonding) electronic state favors the localization of the 5f states. The specific nature of the 5f states in a particular actinide element has consequences for its magnetic and other electronic properties. The chapter also discusses the properties of binary and ternary compounds, the influence of the incorporation of H and B in intermetallic compounds, morphous and icosahedral compounds, and trans-thorium compounds where the 5f-electrons play a dominant role. Materials involving Th are included mainly in cases where they can serve as suitable "background" compounds with unoccupied 5f states.
TL;DR: In this paper, a sensitive system for D,L-amino acid analysis was developed, using fluorescence derivatization with o-phthaldialdehyde in the presence of sodium salt of 1-thio-beta-D-glucose.
01 Jan 1988
TL;DR: The presence of many descending fibers in the auditory pathway has been known for many years and the complexity of the descending auditory pathway is well recognized, but recent findings revealing the role of the olivocochlear bundle in the control of cochlear micromechanics have opened a new era in the investigation of the role.
Abstract: The presence of many descending fibers in the auditory pathway has been known for many years and the complexity of the descending auditory pathway is well recognized. Recent findings revealing the role of the olivocochlear bundle in the control of cochlear micromechanics have opened a new era in the investigation of the role of descending fibres in the auditory pathway. The advent of axonal transport techniques for tracing neuronal connections stimulated reinvestigation of the connections of the olivocochlear bundle originally described by Rasmussen (1946, 1953). New concepts have emerged from the work of Warr and Guinan (1979), who defined two populations of the olivocochlear efferents: lateral and medial olivocochlear neurons. These two populations may be distinguished with respect to their origin in different parts of the superior olivary complex (SOC) and differing projections to the cochlea. The mediator of the olivocochlear bundle is undoubtedly acetylcholine, as was originally proposed by Rasmussen (1960). However, recently also other possible mediators were found with immunohistochemical methods such as enkephalins (Fex and Altschuler, 1981; Eybalin et al., 1984), aspartate and GABA (Fex et al., 1986).
TL;DR: Limiting dilution analysis for minimal frequencies of precursors of the IL‐2 induced killer cells showed increased numbers of lymphokine‐activated killing precursor in this group of patients, which might indicate the abberations of theIL‐2 system in immediate type allergy but the clinical significance of these findings remains to be determined.
Abstract: Natural killer (NK) cell activity and interleukin-2 (IL-2) induced cytotoxicity to NK-resistant targets T24 in a group of patients with grass pollen seasonal asthma were investigated. Acute bronchial provocation with this antigen was also performed and blood samples were taken before and 15 min after the maximal clinical response. NK activity was elevated in this group but there was a significant decrease after acute challenge. IL-2 induced cytotoxicity was also increased and declined after antigen challenge. Limiting dilution analysis for minimal frequencies of precursors of the IL-2 induced killer cells was introduced and showed increased numbers of lymphokine-activated killing precursors in this group of patients. These data might indicate the abberations of the IL-2 system in immediate type allergy but the clinical significance of these findings remains to be determined.
TL;DR: Two Legionella-like organisms isolated from cooling-tower water samples in Czechoslovakia were shown by DNA studies to constitute two new Legionella species, Legionella moravica and Legionella brunensis.
Abstract: Two Legionella -like organisms were isolated from cooling-tower water samples in Czechoslovakia. They were presumptively identified as legionellae by their growth on buffered charcoal-yeast extract agar (BCYE) containing L-cysteine and their absence of growth on BCYE without L-cysteine. Both strains contained predominantly branch-chained cellular fatty acids and were therefore definitively placed in the genus Legionella . They were serologically distinct from other described Legionella species and were shown by DNA studies to constitute two new Legionella species, Legionella moravica (type strain 316-36; ATCC 43877) and Legionella brunensis (type strain 441-1; ATCC 43878).
TL;DR: In this paper, the central limit result for broad classes of M-estimators is refined to moderate and large deviation behavior, and the results are applied in relating the local inaccuracy rate and the asymptotic variance of M -estimator in the location and scale problem.