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On P Systems and Almost Periodicity

Bernardini F., Gheorghe M., Manca V.

Fundamenta Informaticae

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2005

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Vol. 64, nr 1-4

29-42

EN

The study of P systems as a mathematical model for biological systems is an important research topic in the area of membrane computing. In this respect, the detection of periodicity and almost periodicity as aspects of the system dynamics seems to be of particular relevance for understanding many biological processes and their related phenomena. This paper introduces specific notions of periodicity and almost periodicity for (infinite) sequences of multisets, which are used to describe the dynamics of P systems. Specifically, a variant of P systems, called P systems with resources, is considered where the rules always consume a certain amount of resources, which are provided in the form of a periodic input sequence of multisets. It is then shown that P systems with resources are computationally complete (when halting computations are considered) and that, in general, they can generate sequences of multisets that are not even almost periodic (once the constraint of having halting computation is released). However, if P systems with resources are restricted to be deterministic, it is shown that a characterization of the behaviour of a particular class of P systems with resources can be obtained in terms of almost periodicty.

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Funkcjonalny model symulacyjny zespołu synaps zapamiętujących komórki piramidowej hipokampa

Gorzelańczyk E. J., Huflejt M., Kniat J., Laskowska E., Murakowski J., Woźniak P.

Bio-Algorithms and Med-Systems

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2005

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Vol. 1, no. 1/2

217--220

PL

Zaproponowano model komórki piramidowej hipokampa umożliwiający przeprowadzenie obliczeń w środowisku rozproszonym. W modelu uwzględniono: aktywność elektryczną pojedynczych synaps i receptorów glutamatergicznych oraz aktywność jądra komórkowego i transport receptorów. Podstawą modelu jest koncepcja alternatywnego składania genów. Symulator umożliwia na przykład modelowanie potencjałów czynnościowych, efektu przerwy, zjawiska długotrwałego wzmocnienia synaptycznego.

EN

The model of pyramidal cell is proposed. With this model it is possible to make calculations in diffuse environment. This model considers electrical activity of the individual synapses and glutamate receptors, and cell nucleus activity as well as the transport of receptors. The basis of this model is the alternative splicing of genes. The simulator allows for example modeling action potentials, spacing effect, and long term synaptic potentiation.

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An algorithm for calculating the concentration of phytoplankton in a stratified sea with respect to the daily migration of zooplankton. Part 2. Numerical simulation

Dzierzbicka-Głowacka L., Zieliński A.

Oceanologia

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1998

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No. 40 (4)

371-398

EN

The numerical studies were carried out using a (nutrient-phytoplankton-zooplankton-detritus) biological model with a well-developed regeneration block. This paper presents the time-dependent vertical distributions of biological characteristics (concentrations nutrients, phytoplankton and zooplankton and benthic detritus pool) on the assumption that the horizontal distribution of these parameters is uniform. The calculations were made in an area 0 ≤z≤ 20 m with a vertical scale step of 10 cm and a time scale step of 15 min. The experimental data, gathered during the PEX '86 international scientific experiment of the Baltic states, and those by the International Council for the Exploration of the Sea, were used as the input data for the calculations.

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An algorithm for calculating the concentration of phytoplankton in a stratified sea with respect to the daily migration of zooplankton. Part 1. P–V–Z–D model

Dzierzbicka-Głowacka L., Zieliński A.

Oceanologia

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1998

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No. 40 (4)

355-370

EN

This paper presents a nutrient-phytoplankton-zooplankton-detritus biological model with a fully-developed regeneration mechanism with respect to the daily migration of zooplankton. The P-V-Z-D model consists of two partial differential equations of the diffusion type for the concentration of nutrients and phytoplankton, and two ordinary differential equations for the concentration of zooplankton and the benthic detritus pool, together with initial and boundary conditions.