Showing papers by "Charles University in Prague published in 1984"

An alternate version of Pirogov-Sinai theory

Abstract: A new approach to the Pirogov-Sinai theory of phase transitions is developed, not employing the contour models with a parameter. The completeness of the phase diagram is proven.

Prospective study on the relationship between cervical neoplasia and herpes simplex type-2 virus. II. Herpes simplex type-2 antibody presence in sera taken at enrolment

Abstract: Sera obtained at enrollment in the study from patients suffering from moderate to sever dysplasia (cervical intraepithelial neoplasia grade II), carcinoma in situ (cervical intraepithelial neoplasia grade III) and invasive carcinoma, or developing any of these conditions in the course of the prospective study, and from control subjects, were examined for herpes simplex type-2 (HSV-2) antibody presence. The controls were matched with the patients by age, age at first intercourse, number of sexual partners, smoking habits and history of diathermoelectrocoagulation of the ectopic epithelium and transformation zone of cervix. Only those subjects were selected as controls who remained free of pathological colposcopical and cytological findings throughout the observation period, i.e. for at least 4 years after their serum sample was obtained. The microneutralization test (MNT) and type-2-specific solid-phase radioimmunoassay (SPRIA) were used as serological tests. No difference in the prevalence of HSV-2 antibody between the patients and controls was revealed by either test. Various combinations of the results from the two tests also failed to show any difference between patients and controls. Moreover, no significant differences were observed in the prevalence of HSV-2 antibody between patients suffering from the various pathological conditions and those diagnosed at enrollment and later in the course of the study. These results do not provide any support for the hypothesis of the involvement of HSV-2 in cervical neoplasia.

A multilevel iterative method for symmetric, positive definite linear complementarity problems

Abstract: A fast iterative method for the solution of large, sparse, symmetric, positive definite linear complementarity problems is presented. The iterations reduce to linear iterations in a neighborhood of the solution if the problem is nondegenerate. The variational setting of the method guarantees global convergence.

Prospective study on the relationship between cervical neoplasia and herpes simplex type‐2 virus. I. Epidemiological characteristics

Abstract: To determine the risk associated with previous herpes simplex type-2 (HSV-2) infection and possibly other virus infections, a prospective study of cervical neoplasia in more than 10,000 women was performed in the 1975-1983 period. The subjects were selected at random from an alphabetical listing of eligible women living in one district of Prague. At enrollment colposcopy and cervical cytology were performed, a blood sample was taken and data regarding education, socio-economic status, personal habits and sexual and reproduction-associated attributes were obtained from each woman. A total of 10,683 women were enrolled; a complete set of data was obtained in 10,389 women. Women with normal or non-significant findings were invited for further colposcopical and cytological investigations after 2 years and 4 years, the other women were followed at 3- to 6-monthly intervals. In women with highly significant findings, histological investigation was performed. The total of 150 cases of moderate to severe dysplasia (i.e. cervical intraepithelial neoplasia, grade II, CIN II), 83 cases of carcinoma in situ (CIN III) and 21 cases of invasive carcinoma (INCA) were detected. More than 60% of the patients were ill at enrollment, the other cases developed in subjects with originally slightly suspicious (27 CIN II, 17 CIN III, 3 INCA) or negative findings (30 CIN II, 12 CIN III, 3 INCA). Analysis of the data indicated significantly positive correlation of one or more of these clinical conditions with a number of sexual and reproduction-related attributes of which early age at first intercourse was most consistent. Among the other attributes, the smoking habit was associated with the highest risk of developing the disease. A negative correlation of cervical neoplasia with several attributes was demonstrated; of these diathermoelectrocoagulation of the ectopic epithelium and transformation zone of cervix was the most important single protective factor. On the basis of these findings, control subjects were selected for serological studies.

Paraxial ray approximations in the computation of seismic wavefields in inhomogeneous media

Abstract: Summary. Several important applications of the paraxial ray approximation (PRA) to numerical modelling of high-frequency seismic body wavefields are discussed. The PRA can be used to evaluate the displacement vector not only directly on the ray, as in the standard ray method. but also approximately in the vicinity of this ray. The PRA also offers simple ways of approximate evaluation of paraxial rays, situated in the vicinity of the central ray, and of two-point ray tracing. A very important application of the PRA consists in a simple, fast and effective Computation of body-wave synthetic seismograms in general, 3-D, laterally inhomogeneous, layered structures. Examples of synthetic seismograms for 3-D structures, computed using the PRA, are presented.

Combinatorial partitions of finite posets and lattices —Ramsey lattices

Abstract: It is proved that for every finite latticeL there exists a finite latticeL′ such that for every partition of the points ofL′ into two classes there exists a lattice embeddingf:L→L′ such that the points off(L) are in one of the classes.

Numerical modelling and inversion of travel times of seismic body waves in inhomogeneous anisotropic media

Abstract: Summary. Two approaches to travel-time computations in laterally inhomogeneous anisotropic media are presented. The first method is based on ray tracing in an anisotropic inhomogeneous medium, the second on the linearization procedure. The linearization procedure, which can be applied to inhomogeneous, slightly anisotropic media, does not require ray tracing in an anisotropic medium. Applications of linearized equations to the solutions of direct and inverse kinematic problems are discussed. A program package to perform the linearized computations for rather general 2-D laterally inhomogeneous layered structures is described and a numerical example is presented.

Interaction of radium with freshwater sediments and their mineral components

Abstract: Radiotracer method has been used for investigation of the adsorption and desorption of traces of radium on kaolinite and montmorillonite under conditions similar to those prevailing in waste and surface waters. It has been found that adsorption depends on the pH and ionic strength of the solution, and the character of these dependences is different for kaolinite and montmorillonite. Sulfates at concentration 60 mg·l−1 have negligible effect on the adsorption. Montmorillonite represents better adsorbent for radium than kaolinite, but both minerals may significantly affect the form and migration of radium in surface waters, if present as (major) components of freshwater sediments. Radium can be quantitatively desorbed by 1M HCl from kaolinite but not from montmorillonite. The desorption by 0.1M NaCl is generally lower and depends on the pH during the preliminary adsorption. Mechanisms of radium adsorption on both minerals and the character of the adsorption sites are discussed.

Biochemical markers in inbred strains of the rat (Rattus norvegicus)

Abstract: Klaus Bender 1, M a r k Adams 2, Peter R. Baverstock 2, Maria den Bieman 3, Siegbert Bissbort 1, Rad im Brdi~ka 4, Geoffrey W. Butcher 5, Dona ld V. Cramer 6, Otto yon Deimling 7, Michael F .W. Festing 8, Eberhard Gtinther 9, Rona ld D. G u t t m a n n 1°, Hans J. Hedrich 11, Philip B. Kendall 12, Reinhard Kluge i t , Ren6 Moutier 13, Babette Simon 7, James E. W o m a c k ~4, Junzo Yamada ~5, and Bert van Zutphen 3

Expansion of a high-frequency time-harmonic wavefield given on an initial surface into Gaussian beams

Abstract: Summary. A high-frequency asymptotic expansion of a time-harmonic wavefield given on a curved initial surface into Gaussian beams is determined. The time-harmonic wavefield is assumed to be specified on the initial surface in terms of a complex-valued amplitude and a phase. The asymptotic expansion has the form of a two-parametric integral superposition of Gaussian beams. The expansion corresponds to the relevant ray approximation in all regions, where the ray solution is sufficiently regular (smooth) in effective regions of the beams under consideration.

The reciprocal variational approach to the Signorini problem with friction. Approximation results

Abstract: In this paper, a new variational formulation of the Signorini problem with friction is given in terms of the contact stresses. The method corresponds to the direct integral equation approach in classical elastostatic problems. First the displacement and mixed problems are briefly described together with some numerical results. Next the displacements are eliminated by the use of Green's function, and a constrained minimum problem with respect to the normal and tangential tractions on the contact boundary is derived. Then the resulting approximation procedure is studied and certain convergence results are proved. Finally, some remarks on the Signorini problem with Coulomb friction are presented. Numerical results illustrate the theory.

Stability in stochastic programming with recourse-estimated parameters

Abstract: In this paper, stability of the optimal solution of stochastic programs with recourse with respect to parameters of the given distribution of random coefficients is studied Provided that the set of admissible solutions is defined by equality constraints only, asymptotical normality of the optimal solution follows by standard methods If nonnegativity constraints are taken into account the problem is solved under assumption of strict complementarity known from the theory of nonlinear programming (Theorem 1) The general results are applied to the simple recourse problem with random right-hand sides under various assumptions on the underlying distribution (Theorems 2–4)

Gaussian beams in elastic 2-D laterally varying layered structures

Abstract: Summary. In a paper by Cervený & Psencik, high-frequency Gaussian beams in elastic 2-D, laterally inhomogeneous, smooth media were investigated as asymptotic high-frequency solutions of elastodynamic equations, concentrated close to rays of P- and S-waves. This paper generalizes the above results for 2-D, laterally inhomogeneous, layered structures. Gaussian beams concentrated close to any multiply-reflected, possibly converted, ray are investigated. Gaussian beams are regular everywhere, including caustic regions. The paraxial ray approximation, which allows the wavefield in the zero-order ray approximation to be evaluated not only directly on the ray, but also in its vicinity, is derived as a limiting case of the Gaussian beams.

Convergence of the cyclical relaxation method for linear inequalities

Abstract: The relaxation method for linear inequalities is studied and new bounds on convergence obtained. An asymptotically tight estimate is given for the case when the inequalities are processed in a cyclical order. An improvement of the estimate by an order of magnitude takes place if strong underrelaxation is used. Bounds on convergence usually involve the so-called condition number of a system of linear inequalities, which we estimate in terms of their coefficient matrix.

Effect of external factors on hibernation of golden hamsters

Abstract: 1. Hibernation of golden hamsters begins after about 2 months exposure to cold and dark, occurs repeatedly for a further 6 months and then ceases. Constant light reduces the frequency of hibernation only slightly. 2. There is an inverse relation between occurrence of hibernation and gonadal activity. Continuous exposure to dark or cold or both induces gonadal involution within 30–60 days and spontaneous recrudescence of gonads occurs after about 7 months under these conditions. Application of testosterone prevents hibernation. 3. Gonadal functions are not the only factor involved in the control of hibernation. Castration has a slightly positive effect on hibernation and in castrated individuals hibernation ceases after several months in the cold, similar to controls. 4. Application of melatonin to golden hamsters exposed to cold and dark does not influence hibernation pattern. The effect of cold on gonadal involution and on hibernation is not mediated by the pineal because pinealectomized animals exposed to cold, and intact hamsters kept in continuous light and cold, undergo gonadal involution and hibernate. 5. Under controlled laboratory conditions hibernation of golden hamsters can be induced at any time of the year, providing that gonadal activity is maintained at a low level. No strict adherence of hibernation to a circannual rhythm was detected. Exogenous cues are required to establish seasonality of hibernation.

Gateaux differentiable functions are somewhere Frechet differentiable

Abstract: It is proved that every everywhere Gateaux differentiable real-valued Lipschitz function on an Asplund space is Frechet differentiable at uncountably many points. The nonseparable case is reduced to the separable one with the help of a general separable reduction theorem.

The sexual development and life of female schizophrenic patients.

Abstract: The sexual development of 51 female schizophrenics, their attitudes toward sex, and their sexual activity and arousability were investigated. The control group consisted of 101 gynecological patients. The sexual development of the female schizophrenics was significantly retarded, and their sexual activity and arousability significantly lowered in adult life compared with the control group. The hypothesis is advanced that the retarded development may be caused by some biological factor, while sexuality in adult life is negatively affected primarily by social isolation.

The relation between Gaussian beams and Maslov asymptotic theory

Abstract: The application of Maslov asymptotic theory in a general 3-D mixed subspace of 6-D complex phase space is proposed to obtain the integral superpositions of Gaussian packets and beams. The ray method and the superposition of plane waves (Maslov method of Chapman and Drummond [7]) are special limiting cases of the above mentioned approach. The same high-frequency asymptotic expansion formulae for seismic body waves were derived previously in [8] using the Gaussian beam method.

Monte Carlo study of the three-state square Potts antiferromagnet

Abstract: The role of a new type of vortices introduced in the three-state squares Potts antiferromagnet for decay of correlations is considered. Fluctuations of the vortex charge in a region are measured using the Monte Carlo method. Data suggest an exponential decay of correlations. At zero temperature, an equivalent surface model is considered. A Monte Carlo experiment indicates roughening, thus suggesting an algebraical decay of the zero temperature Potts antiferromagnet.