There are conflicting results concerning the receptor subtype(s) involved in calcium-mediated endothelin signaling in the glial cells. In order to elucidate the role of endothelin A and B receptors in these processes, we have studied the effect of a complex spectrum of endothelin receptor ligands on intracellular calcium concentration changes in proliferating and differentiated C6 rat glioma cells. Cell differentiation was induced by dibutyryl-cAMP and assessed by the glial fibrillar acidic protein content. Intracellular calcium changes were measured in cell suspensions using fluorescent probe Fura-2. The specific endothelin B receptor agonists sarafotoxin S6c and IRL-1620 did not influence the intracellular calcium concentration. However, calcium changes induced by endothelin-1 and especially by endothelin-3 after the pretreatment of cells with one of these endothelin B receptor specific agonists were significantly enhanced even above the values attained by the highest effective endothelin concentrations alone. Such endothelin B-receptor ligand-induced sensitization of calcium signaling was not observed in differentiated C6 cells. Moreover, endothelin-induced calcium oscillations in differentiated C6 cells were less inhibited by BQ-123 and BQ-788 than in their proliferating counterparts. In conclusion, the specific activation of endothelin B receptor in C6 rat glioma cells does not affect intracellular calcium per se, but probably does so through interaction with the endothelin A receptor. The pattern and/or functional parameters of endothelin receptors in C6 rat glioma cells are modified by cell differentiation., R. Malík, K. Vlašicová, A. Šedo., and Obsahuje bibliografii
The method of quasilinearization is a well-known technique for obtaining approximate solutions of nonlinear differential equations. In this paper we apply this technique to functional differential problems. It is shown that linear iterations converge to the unique solution and this convergence is superlinear.
Some functional representation theorems for monadic n-valued Luk asiewicz algebras (qLkn-algebras, for short) are given. Bearing in mind some of the results established by G. Georgescu and C. Vraciu (Algebre Boole monadice si algebre L ukasiewicz monadice, Studii Cercet. Mat. 23 (1971), 1027–1048) and P. Halmos (Algebraic Logic, Chelsea, New York, 1962), two functional representation theorems for qLkn-algebras are obtained. Besides, rich qLkn-algebras are introduced and characterized. In addition, a third theorem for these algebras is presented and the relationship between the three theorems is shown.
Neuroimaging methods have been used to study differences of brain function between males and females. Differences in working memory have been also investigated, but results of such studies are mixed with respect to behavioral data, reaction times and activated brain areas. We tried to analyze functional MRI data acquired during the working memory task and search for differences of brain activation between genders. 20 healthy righthanded volunteers (10 males and 10 females) participated in the study. All of them were university students or fresh graduates. Subjects underwent block designed verbal working memory task (Item Recognition Task) inside the MRI scanner. Standard singlesubject pre-processing and group fMRI analyses were performed using the FEAT software from FSL library. In the behavioral data, there was no statistically significant difference in the number of correct responses during the task. The task activated similar bilateral regions of frontal, parietal, temporal and occipital lobes, basal ganglia, the brainstem and in the cerebellum, which corresponds to the previous verbal working memory neuroimaging research. In direct comparison, there was no statistically significant difference in brain activation between small samples of male and female young healthy volunteers., Z. Tüdös, P. Hok, P. Hluštík, A. Grambal., and Obsahuje bibliografii
This paper is concerned with the functional observer design for a class of Multi-Input Multi-Output discrete-time systems with mixed time-varying delays. Firstly, using the Lyapunov-Krasovskii functional approach, we design the parameters of the delay-dependent observer. We establish the sufficient conditions to guarantee the exponential stability of functional observer error system. In addition, for design purposes, delay-dependent sufficient conditions are proposed in terms of matrix inequalities to guarantee that the functional observer error system is exponentially stable. Secondly, we presented the sufficient conditions of the existence of internal-delay independent functional observer to ensure the estimated error system is asymptotically stable. Furthermore, some sufficient conditions are obtained to guarantee that the internal-delay independent functional observer error system is exponentially stable. Finally, simulation examples are provided to demonstrate the effectiveness of the proposed method.
A sufficient condition for the nonexistence of blowing-up solutions to evolution functional-differential equations in Banach spaces with the Riemann-Liouville integrals in their right-hand sides is proved. The linear part of such type of equations is an infinitesimal generator of a strongly continuous semigroup of linear bounded operators. The proof of the main result is based on a desingularization method applied by the author in his papers on integral inequalities with weakly singular kernels. The result is illustrated on an example of a scalar equation with one Riemann-Liouville integral.
U-statistics of spatial point processes given by a density with respect to a Poisson process are investigated. In the first half of the paper general relations are derived for the moments of the functionals using kernels from the Wiener-Itô chaos expansion. In the second half we obtain more explicit results for a system of U-statistics of some parametric models in stochastic geometry. In the logarithmic form functionals are connected to Gibbs models. There is an inequality between moments of Poisson and non-Poisson functionals in this case, and we have a version of the central limit theorem in the Poisson case.
The exponential stability property of an evolutionary process is characterized in terms of the existence of some functionals on certain function spaces. Thus are generalized some well-known results obtained by Datko, Rolewicz, Littman and Van Neerven.
We introduce a notion of a function of finite fractional variation and characterize such functions together with their weak σ-additive fractional derivatives. Next, we use these functions to study differential equations of fractional order, containing a σ-additive term-we prove existence and uniqueness of a solution as well as derive a Cauchy formula for the solution. We apply these results to impulsive equations, i.e. equations containing the Dirac measures., Dariusz Idczak., and Obsahuje bibliografii
The article is written in the form of a review paper containing four fundamental color classification systems for the digital imaging colorimetry. Such a branch is based commonly on exploitation of a digital three-channel color camera adapted for objective color measurements and connected with an evaluational and processing PC. The relevant fundamental color (colorimetric) classification systems under consideration in this article are: the additive color system (R,G,B), the subtractive color system (C,M,Y), the CIE color system (X,Y,Z) and the CIE color system (L*,a*,b*). and Článek je napsán v přehledné formě obsahující čtyři základní klasifikační systémy barev pro digitální zobrazovací kolorimetrii. Tento obor je obvykle založen na využití digitální tříkanálové barevné kamery upravené pro objektivní měření barev a spojené s vyhodnocovacím a zpracovávacím počítačem. Příslušné základní barevné (kolorimetrické) klasifikační systémy, uvažované v tomto článku, jsou: aditivní barevný systém (R,G,B), subtraktivní barevný systém (C,M,Y), CIE barevný systém (X,Y,Z) a CIE barevný systém (L*,a*,b*).