Wyniki wyszukiwania - BazTech

1

Membrane Creation in Polarizationless P Systems with Active Membranes

Orellana-Martín David, Valencia-Cabrera Luis, Riscos-Núñez Agustín, Pérez-Jiménez Mario J.

Fundamenta Informaticae

|

2020

|

Vol. 171, nr 1-4

297--311

EN

Biological membranes play an active role in the evolution of cells over time. In the framework of Membrane Computing, P systems with active membranes capture this idea, and the possibility to increase the number of membranes during a computation. Classically, it has been considered, by using division rules, inspired in the mitosis process. Initially, the membranes in these models are supposed to have an electrical polarization (positive, negative or neutral) and the semantics is minimalist, in the sense that rules are applied in parallel, but in one transition step, each membrane can be the subject of at most one rule of types communication, dissolution or division. This paper focuses on polarizationless P systems with active membranes in which membrane creation rules are considered instead of membrane division rules as a mechanism to construct an exponential workspace, expressed both in terms of number of objects and membranes, in linear time. Moreover, the minimalist semantics is considered and some complexity results are provided in this framework, allowing to tackle the P versus NP problem from a new perspective. An original frontier of the efficiency in this context is unveiled in this paper: allowing membrane creation rules to be applicable in any membrane of the system, instead of restricting them to only elementary membranes, yields a significant boost on the computational power. More precisely, only problems in P can be efficiently solved in the restricted case, while in the non-restricted case an efficient and uniform solution to a PSPACE-complete problem is provided.

2

Porównanie wpływu naturalnych oraz syntetycznych surfaktantów na monowarstwę DPPC

Orczyk M., Wojciechowski K.

Inżynieria i Aparatura Chemiczna

|

2014

|

Nr 4

278--279

PL

W pracy zbadano oddziaływania surfaktantów syntetycznych (SDS, CTAB, Triton X-100) oraz biosurfaktantu – saponiny – Quillaja saponaria Molina (QBS) na monowarstwę modelowego fosfolipidu DPPC jako najprostszego układu symulującego błonę lipidową. Eksperymenty przeprowadzono przy użyciu wanny Langmuira-Blodgett o powierzchni aktywnej 77,5 cm2 (KSV NIMA). Stwierdzono, że biosurfaktant QBS, w przeciwieństwie do surfaktantów syntetycznych wbudowuje się w monowarstwę DPPC.

EN

In this work authors compared the effect of (bio)surfactants on a model membrane consisting of DPPC monolayer. The results show that Quillaja saponaria Molina (QBS, Quillaja bark saponin) displays a unique effect on the model lipid. In contrast to synthetic surfactants it does not remove the lipid layer but incorporates into it.

3

Length P Systems

Alhazov A., Freund R., Ivanov S.

Fundamenta Informaticae

|

2014

|

Vol. 134, nr 1/2

17--37

EN

In this paper, we examine P systems with a linear membrane structure, i.e., P systems in which only one membrane is elementary and the output of which is read out as the sequence of membrane labels in the halting configuration or vectors/numbers represented by this sequence. We investigate the computational power of such systems, depending on the number of membrane labels, kinds of rules used, and some other possible restrictions. We prove that two labels, elementary membrane creation and dissolution, together with the usual send-in and send-out rules, suffice to achieve computational completeness, even with the restriction that only one object is allowed to be present in any configuration of the system. On the other hand, limiting the number of labels to one reduces the computational power to the regular sets of non-negative integers. We also consider other possible variants of such P systems, e.g., P systems in which all membranes but one have the same label, P systems with membrane duplication rules, or systems in which multiple objects are allowed to be present in a configuration, and we describe the computational power of all these models.

4

An Application of Graphical Numerical Accelerators in Simulations of Ion-Transport Through Biological Membranes

Górecki A.

Computational Methods in Science and Technology

|

2013

|

Vol. 19, No. 1

33--46

EN

The modeling of ion-transport through biological membranes is important for understanding many life processes. The transmembrane potential and ion concentrations in the stationary state can be measured in in-vivo experiments. They can also be simulated within membrane models. Here we consider a basic model of ion transport that describes the time evolution of ion concentrations and potentials through a set of nonlinear ordinary differential equations. To reduce the computation time I have developed an application for simulation of the ion-flows through a membrane starting from an ensemble of initial conditions, optimized for a Graphical Processing Unit (GPU). The application has been designed for the CUDA (Compute Unified Device Architecture) technology. It is written in CUDA C programming language and runs on NVIDIA TESLA family of numerical accelerators. The calculation speed can be increased almost 1000 times compared with a sequential program running on the Central Processing Unit (CPU) of a typical PC.

5

The possibilities of modelling the membrane separation processes using artificial neural networks

Kabsch-Korbutowicz M., Kutyłowska M.

Environment Protection Engineering

|

2008

|

Vol. 34, nr 1

15-35

EN

Despite the substantial progress observed in last years in membrane science, many initial problems associated with membrane processes have not been solved, including limitations in ability to control and predict membrane fouling and selectivity. That is why a suitable method for process optimization should be developed which will allow the most important membrane parameters to be modelled. The paper describes the possibilities of forecasting the parameters of the membrane processes using artificial neural network (ANN). The modelled parameters vary in their properties, so different ANN may be used for their testing and forecasting.

PL

Pomimo znaczącego w ostatnich latach rozwoju technik membranowych pozostało jeszcze wiele problemów związanych z procesami separacji, a także ograniczeń w kontrolowaniu foulingu i selektywności membran. Dlatego konieczny jest rozwój metod optymalizacji, które umożliwiają zamodelowanie najważniejszych parametrów procesów membranowych. W artykule opisano możliwości prognozowania parametrów procesów membranowych z użyciem sztucznych sieci neuronowych. Właściwości modelowanych parametrów są zmienne, dlatego do testowania i prognozowania użyto różnych typów sieci neuronowych.

6

Application of the H-infinite control for multi-states conformational transition of calcium ion selective gating channels on excitable cellular membranes

Hirayama H.

Systems Science

|

2002

|

Vol. 28, nr 1

107-34

EN

We introduced H infinite control theory for evaluating the noise filtering functions of biological membranes. Calcium ion selective gating channel on excitable cellular membranes was described by four subunits allosteric modeling. The modeling was characterized by cooperative positional changes of an intrinsic voltage sensitive molecule in each of the subunits and concerted conformational changes of all the subunits. We applied the H-infinite control strategy for minimizing the influence of noises as the worst disturbances on the filtering function of the calcium channel. The allosteric cooperative positioning of the S4 and concerted actions of the subunits were approximated by powers of non-dimensional parameter F/sup n/. The temporal changes in amounts of calcium channel states were described by ten differential equations. We induced the corresponding differential equations for observers and accompanied Riccati equations. The transient changes in amounts per unit membrane area of calcium ion channel species were almost parallel. Those of the observers were a variety of patterns. The change in amount of control input for the concerted opening was the smallest while those for inter open states transitions were the largest. The computed temporal changes in the worst disturbances and the worst noises showed characteristic time courses for individual channel species and observers.

7

Allosteric systems on biological membrane analysis by time minimum optimal control principle

Hirayama H., Okita Y.

Systems Science

|

2000

|

Vol. 26, nr 4

121-145

EN

We calculated temporal changes in concentrations of species in biological allosteric system. The allosteric nature was described by co-operativity and concerted actions of identical subunits composing the system. The co-operativity was characterized by accelerated bindings of substrates to the subunits and their structural changes. The concerted mechanism provokes all or non-conformational change of an entire molecule from its inactive to active sate at one time. As the number of bound substrate increases, the concerted conformational transition of all the subunits strongly directs to active state. These two properties save the time to complete activation of the system and full substrate binding. The allosteric actions are frequently observed in the critical emergency conditions such as oxygen binding, immune defense reaction and ionic channel gating on excitable membrane of the bio-signal transmission. Hence, the temporal actions of allosteric systems can be interpreted as the shortest time controlled system. We thus, proposed the time minimum optimal control principle as an organizing strategy for activating and binding processes of the allosteric systems. We presented fifteen non-linear differential equations for describing the temporal changes in concentrations of the species composing a two activators-two substrates allosteric system. Another set of fifteen non-linear differential equations for co-state variables were obtained by partial differentiation of the Hamiltonian of the system based on the minimum optimal control theory. The computed temporal concentrations of species oscillated. A reduction of an allosteric parameter shifted these temporal changes synchronously. When the amounts of substrate and activator were set as time invariant, the oscillations disappeared and the concentration of the species approached a steady level. These computed results are qualitatively consistent with actual biophysical phenomena. The present mathematical description of transient changes in concentrations of species in biological allosteric system will be available for evaluating the effective and economical performance of the allosteric system acting under the critical emergency circumstances.