Showing papers by "Charles University in Prague published in 1983"

Three-dimensional analysis of dendritic spines. I. Quantitative observations related to dendritic spine and synaptic morphology in cerebral and cerebellar cortices.

Abstract: A total of 342 dendritic spines (193 from the visual and 149 from the cerebellar cortex of the mouse) were analyzed in serial and several hundred of thousands of them in single sections, with respect to the presence and organization of the spine apparatus and other cytoplasmic components. The continuity of the spine apparatus with the smooth endoplasmic reticulum of the dendritic trunk was shown in three-dimensional reconstructions. The dense material of the spine apparatus was divided into “inner dense plate” and “outer dense plate”. The close relationship between the outer dense plate and the postsynaptic density suggests that the spine apparatus functions as a postsynaptic protein synthesizing centre. The material from the outer dense plate could be used for a dynamic extension of the synaptic active zone. An extraspinous spine apparatus of the axon initial segment was partially reconstructed. Polyribosomes were found in all large spines of the visual cortex but were not so frequent in small spines and in Purkinje cell dendritic spines. Microfilamentous network and intermediate filaments occurred in the spines. The smooth endoplasmic reticulum of Purkinje cell dendritic spines was reconstructed. No spine apparatus and dense material were present in these spines.

Linear filtering of VLF dip-angle measurements

Abstract: The suggested interpretation technique is based on discrete linear filtering of VLF data. The output of the described filtering results is expressed in terms of an equivalent current density at a specified depth that would cause the measured magnetic field. The most practical six-point filter gives an accuracy of 8%. The filter is an extension of the commonly used Fraser filter to process VLF dip-angle data. Filtering the same data set for various depths gives an idea about the change of current density with depth. Areas with high current-density correspond to good conductors. The conductor dip can also be determined. The use of the technique is illustrated on theoretical and field examples. In all cases a good correlation with original models and other types of geophysical measurements was obtained. As shown in the last example, the filtering technique is also applicable in interpretation of other electromagnetic methods.

Synthetic body wave seismograms for laterally varying layered structures by the Gaussian beam method

Abstract: Summary. Several approaches to computing body wave seismograms in 2–D and 3–D laterally inhomogeneous layered structures are suggested. They are based on the Gaussian beam method, which has been recently applied to the evaluation of time-harmonic high-frequency wavefields in inhomogeneous media. Three variants are discussed in some detail: the spectral method, the convolutory method and the wave-packet method. The most promising seems to be the wave-packet approach. In this approach, the wavefield, generated by a source, is expanded into a system of wave packets, which propagate along rays from the source in all directions. The wave packets change their properties due to diffusion, spreading, reflections/transmissions, etc. The resulting seismogram at any point of the medium is then obtained as a superposition of those packets which propagate close to the point. The final expressions in all the three methods are regular even in regions, in which the ray method fails, e.g. in the vicinity of caustics, in the critical region, at boundaries between shadow and illuminated regions, etc. Moreover, they are not as sensitive to the minor details of the medium as the ray method and, what is more, they remove the time-consuming two-point ray tracing from computations. Numerical examples of synthetic seismograms computed by the wave-packet approach are presented.

Gas and high-performance liquid chromatography of phenols

Abstract: Gas and high-performance liquid chromatographic methods in the analysis of phenols are reviewed. Among the great number of phenolic compounds analyzed, alkylphenols, chlorophenols, dihydroxy- and trihydroxybenzenes and biphenols are chiefly considered. The advantages and drawbacks of the methods are discussed, quoting the most important work. Relationships between the structural characteristics of phenols, the stationary phase structure, the mobile phase composition and the retention data are treated. Typical examples of the conditions for GC and HPLC analysis are summarized in tables. The literature comprises over 270 references, most of them recent.

Tandem scanning reflected light microscopy of internal features in whole bone and tooth samples.

Abstract: SUMMARY An improved version of the tandem-scanning reflected-light microscope (Petran et al., 1968) has been studied with respect to its applicability to the study of mammalian mineralized tissues. It was found to have important advantages compared with other light microscopic methods, since it allowed microscopic structures to be seen at considerable depths within intact specimens. It has a small depth of focus and gives high contrast for features such as osteocyte lacunae and canaliculi in bone, and prism boundaries in dental enamel.

Method of continued fractions with application to atomic physics

Abstract: A new iterative method for solving scattering integral equations for local as well as nonlocal potentials is proposed. The scattering matrix is expressed in the form of a continued fraction. This method converges extremely fast for compact potentials with arbitrary strength. A high precision of the result is expected with a relatively small amount of numerical work. Starting from the second iteration, all functions which are to be computed in the course of iterations are regular at the origin and are of finite range in configuration space. The method is applied to the elastic scattering of electrons from hydrogen atoms in the static, exchange approximation. Its efficiency is compared with some recently proposed methods.

Gaussian beams in two-dimensional elastic inhomogeneous media

Abstract: Summary. Asymptotic high-frequency solutions of elastodynamic equations in two-dimensional laterally inhomogeneous media concentrated close to rays of P- and S-waves are investigated. From a physical point of view, these vectorial solutions correspond to Gaussian beams; the amplitude distribution of their principal components is bell-shaped along the direction perpendicular to the ray. The principal component of the elastodynamic Gaussian beam is controlled by the parabolic equation, which has exactly the same form as the parabolic equation for scalar Gaussian beams. The elastodynamic Gaussian beams are regular everywhere, including caustics.

Association of some supraglottic laryngeal carcinomas with EB virus

Abstract: Thin sections of biopsies from five patients with supraglottic laryngeal carcinoma who possessed antibody to early antigen of EB virus were examined for the presence of EB virus nuclear antigen (EBNA) and EB virus DNA by cytological hybridization in situ. Both EBNA and EB virus DNA were found in the tumour cells of three of the patients. The present findings suggest an association between EB virus and supraglottic carcinoma of the larynx.

Representations of the Poincaré group associated with unstable particles

Abstract: The problem of a relativistically covariant description of unstable particles is reexamined. We follow the approach which associates a unitary reducible representation of the Poincar\'e group with a larger isolated system, and compare it with the one ascribing a nonunitary irreducible representation to the unstable particle alone. It is shown that the problem originates in the choice of the subspace ${\mathcal{H}}_{u}$ of the state Hilbert space which could be related to the unstable particle. Translational invariance of ${\mathcal{H}}_{u}$ is proved to be incompatible with unitarity of the boosts. Further, we propose a concrete choice of ${\mathcal{H}}_{u}$ and argue that in most cases of the actual experimental arrangements this subspace is effectively one dimensional. A correct slow-down for decay of the moving particles is obtained.

Niemann-Pick disease (variation in the sphingomyelinase deficient group) Neurovisceral phenotype (A) with an abnormally protracted clinical course and variable expression of neurological symptomatology in three siblings

Abstract: We report three families with five cases of sphingomyelinase (SMase) deficiency, early neurovisceral symptomatology, and a conspicuously protracted course (7–22 years) in contrast to the characteristic acute, rapidly lethal course in classical type A cases. Most of the visceral symptoms were hepatomegaly and splenomegaly, with numerous foam cells in the bone marrow, some of them containing ceroid (sea-blue histiocytes). Histochemical and chemical biopsy studies (liver, skin, bone marrow) revealed macrophage and epithelial sphingomyelinosis and profound SMase deficiency. The dominant neurological symptoms in three of the cases included extrapyramidal involvement, marked mental deficiency, and cherry red spots in the fundus oculi of all the 5 cases. There was, however, a striking variability in the clinical signs in three siblings. The first of them, a girl, died at 7 years from purely visceral involvement with massive affection of the lungs. Despite the absence of clinically detectable, neurological symptomatology there was discrete regional neuronal storage in the brain. Her two younger brothers are still alive. The elder one (22 years) has been reduced to complete neurological invalidism while his younger brother (18 years) has no demonstrable neurological changes, and enjoys normal social integration. Symptomatologically, he is difficult to distinguish from type B, especially from its rare variants with retinal involvement. The discussion is devoted to differences between types A and B of the SMase deficiency and to the neurological symptomatology apparently independent of the gene dose in the three siblings.

Studies on lectins. LVII. Immunofluorescence localization of lectins present in fish ovaries.

Abstract: The occurrence of endogenous lectins in the ovaries of four fish species has been studied by indirect immunofluorescence staining with antibodies against individual lectins. Paraffin sections of the ovary of perch (Perca fluviatilis L.) were treated with an antibody against perch lectin. In cryostat sections of the tench (Tinca tinca L.) ovary, the l-rhamnose-specific lectin “I” was detected with a specific antibody. In cryostat sections of both roach (Rutilus rutilus L.) and rudd (Scardinius erythrophthalmus L.) ovaries, lectins were localized using a single antibody against roach lectin. The isolation of tench lectins is briefly described. In the fish species employed for this study, lectins are associated exclusively with the content and surrounding membrane of cortical vesicles situated within the cytoplasm of maturing oocytes. The positive reaction with lectin antibody was observed almost immediately after the formation of the first cortical vesicles in the peripheral cytoplasm of early previtellogenic oocytes. Their lectin content increases during the later stages when cortical granules fill the whole cytoplasm before moving towards the cell periphery, as the oocyte starts to accumulate yolk. The presence of lectins within cortical vesicles is significant also in view of the polysaccharide content of these structures. In the vitellogenic oocytes lectins seem to move towards the cell periphery and accumulate beneath the plasma membrane. Our observations are discussed in view of the present ideas on the intracellular function of lectins, and with respect to the role of cortical vesicles in fertilization and in postfertilization modifications of the egg envelopes.

Expansion of geoid heights over a triaxial earth's ellipsoid into a spherical harmonic series

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Parental and interpersonal relationships of transsexual and masculine and feminine homosexual men.

Abstract: A group of transsexual and homosexual men was examined using the Leary Test as a psycho-sociogram, and findings were compared to those from a group of heterosexual men. It was found that the fathers of homosexuals and transsexuals were more hostile and less dominant than the fathers of the control group and hence less desirable identification models. The average mothers of transsexuals were close to the ideal person in our culture, e.g., dominant, strong and kindly, and thus an imposing identification model. Heterosexual men and transsexuals, in their behavior towards their wives, on the average identified with the models set by their fathers. Effeminate homosexuals in relations towards their male partners on the average identified with their mothers. Non-effeminate homosexuals modeled their behavior somewhere between both parents. Heterosexual men tended to choose wives modelled on their mothers and modelled their behavior towards their wives on their fathers' behavior. Non-effeminate homosexuals tended to choose their male partners according to the model set by their mothers and behaved toward them in a more dominant manner than any of the other groups studied (effeminate homosexuals, non-effeminate homosexuals and transsexuals). Effeminate homosexuals on average chose the most dominant male partners and modelled their behavior toward them on that of their mothers. The wives of transsexuals were rated as the most hostile. The self-esteem of all the groups studied suffered from lack of dominance. On the average, non-effeminate homosexuals were found to be closest to the heterosexual norms, transsexuals the furthest.

Complex-quaternionic analysis applied to spin–½ massless fields

Abstract: In the paper the complex-quaternionic analysis and its spinor version is used for the study of integral formulas for spin ½ massless fields. The basic corrspondence between the complexified Fueter equation and the massless field equation (spin½) is described first, together with the corresponding Cauchy integral formulas. It is shown then how the complexified Cauchy integral formula can be used to give the connection between elliptic type (boundary value type) integral formulas on Euclidean spacetime and Kirchhoff type (initial value type) integral formulas on Minkowski space (for spin ½ massless fields). The explicit formulas showing such connection with the integral formula described by Penrose are given.

Coercivity and Microstructure of Low‐Alloy CrMo Steel

Abstract: The microstructure of samples of low-alloy CrMo steel subjected to various heat treatments is studied by transmission electron microscopy. The observations indicate that the decisive factors which control the coercive force Hc are the density and the arrangement of the dislocations. The precipitates have only a secondary effect. The observed linear dependencc of Hc vs. ϱ1/2 (ϱ dislocation density) confirms well theoretical predictions. Die Mikrostruktur von Proben aus niedrig legiertem CrMo-Stahl nach verschiedenen Warmebehandlungen wird mittels Durchstrahlungselektronenmikroskopieuntersucht. Die Beobachtungen deuten an, das die fur die Koerzitivkraft Hc maagebenden Faktoren die Dichte und Verteilung von Versetzungen sind. Die Einschldsse haben nur einen sekundaren Effekt. Die beobachtete lineare Abhangigkeit von Hc uber ϱ1/2 (ϱ Versetzungsdichte) bestatigt gut die theoretischen Voraussagen.

Niemann-Pick disease: lipid storage in bone marrow macrophages.

Abstract: A histochemical study of lipids in bone marrow smears was performed in a series of 15 cases of Niemann-Pick disease (NPD). It revealed significant differences in the amount of lipids stored in macrophages of sphingomyelinase (SMase) deficiency (types A, B) and type C. Early deposition of uniform, anisotropic droplets of sphingomyelin (Maltese-cross birefringence) in lysosomes was a feature of a 9-member group of SMase deficiency (types A, B). The type C group (six cases) was characterized by a remarkable difference in the degree of phospholipid, mainly sphingomyelin, deposition. The total amount of phospholipids was small on average, and very often inversely proportional to pronounced structural storage changes. This indirect relationship was most prominent in the early phase of the disease and grew less prominent as the disease progressed further. The stored lipid was primarily isotropic. In longer lasting cases of both categories (SMase deficiency and type C) a considerable part of the storage cell population displayed ceroid deposition giving the appearance of a 'sea-blue histiocyte' independent of the type of NPD, but with definite predominance in SMase deficiency. The diagnostic value of the findings is discussed, and some pathogenetic conclusions suggested, particularly as regards type C. Lipid histochemistry of bone marrow smears is highly recommended as it represents a simple but highly efficient approach, capable of yielding valuable diagnostic information.

Robust Estimators of Location anD Regression Parameters and their Second Order Asymptotic Relations

Abstract: Second order asymptotic relations-namely the orders of asymptotic equivalence — of some pairs of robust estimators are studied. More specifically, we shall study the relations of α-trimmed mean to Huber’s estimator of location and of α-trimmed least-squares estimator to Huber’s estimator of regression, respectively, and the order of the approxiaation of an M-estimator by its one-step version.