A new approach to computer modelling of neuronal stochastic activity is described. The output dynamic activity which depends on the types and the number of input synapses, weights of the synaptic efficacy, the absolute refractory phase duration and threshold level is evaluated on this model in some types of Gaussian input processes. The behaviour of this model for one excitatory and one inhibitory synapse is described in dependence on the changes of excitation weight. The neuronal behaviour presented depends on the number of interspike intervals and the excitation weight and interspike interval density distribution. A novel concept of the e-curve is being introduced, which shows the dependence of the number of output interspike intervals on the weight of excitation on a stable inhibition level, the absolute refractory phase value and the threshold level. The properties of e-curves are discussed. Furthermore, examples of transformations of input stochastic processes are mentioned from the aspect of density distribution changes of interspike intervals.
The computer simulation of space-temporal summation of post-synaptic potentials of neurone’s membrane demonstrated the outstanding changes in the inner time structures of generated interspike intervals. The output time series of ISIs were studied using non-standard kind of time analysis - recurrence plot method. Using this technique we observed phenomenon of unification in inner time structures of output series. Further we identified such parameters of model which exerted the most considerable influence on this phenomenon.
Technologii molekulární epitaxe, známou pod zkratkou MBE (Molecular Beam Epitaxy), není třeba fyzikální obci zvlášť představovat. Tato tenkovrstvá technologie, jejíž předností je příprava krystalicky dokonalých vrstev s tloušťkou od jedné monovrstvy výše a s nejostřejšími rozhraními mezi nimi, našla již v polovodičové fyzice své pevné místo. Její podíl na rozvoji důležité oblasti fyziky pevných látek posledních patnácti let - nízkorozměrových polovodičových nanostruktur - je zásadní. V tomto přehledu si připomeňme již dvacetiletou historii této technologie ve FZÚ AV ČR a cesty, jimiž se zde vyvíjela., M. Cukr, V. Novák., and Obsahuje seznam literatury
The biochemical model of excitation-contraction coupling in cardiomyocyte is presented and the validity of simulations of both physiological and pathological processes is discussed. The model of regulatory and actomyosin subsystems, even if it is rather simple in its regulatory subunit, gives results well consistent with experimental data. Specifically, intracellular free calcium levels ([Ca2+]i) were computed under various states of sarcoendoplasmic reticular Ca2+-ATPase (SERCA2) and compared to experimental findings. Computed results reproduced well both the increase in resting [Ca2+]i level and the attenuation of [Ca2+]i decline commonly observed in heart failure. Thus the computational simulations could help to identify core relations in studied systems by comparing results obtained using similar models of various complexities., M. Mlček, J. Neumann, O. Kittnar, V. Novák., and Obsahuje bibliografii