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1.
Using fuzzy set theory, we created a system, that assesses a herb's usefulness for the treatment of tuberculosis, based on ethnobotanical data. We analysed two systems which contain different amount of inputs. The first system contains four inputs, the second one contains six inputs. We used the Takagi-Sugeno-Kanga model. Mamdani model is poor at representation as it needs more fuzzy rules than that of TSK to model a real world system where accuracy is demanded. It has been employed a fuzzy controller, and a fuzzy model, in successfully solving difficult control and modelling problems in practice. It is implemented in the Fuzzy Logic Toolbox in Matlab. The data for inputs are gathered in the database named SOPAT (selection of plants against tuberculosis), which is part of a project coordinated by the Oxford International Biomedical Centre. In this database there could be up to one million plant species. It would be cumbersome to select a remedy from one (or some) of these species looking at the data base one-by-one. By means of the fuzzy set theory this remedy can be chosen very quickly. 相似文献
2.
On the possible methods for the mathematical description of the ball and chain model of ion channel inactivation 总被引:1,自引:0,他引:1
Ion channels are large transmembrane proteins that are able to conduct small inorganic ions. They are characterized by high
selectivity and the ability to gate, i.e. to modify their conductance in response to different stimuli. One of the types of
gating follows the ball and chain model, according to which a part of the channel’s protein forms a ball connected with the
intracellular side of the channel by a polypeptide chain. The ball is able to modify the conductance of the channel by properly
binding to and plugging the channel pore. In this study, the polypeptide ball is treated as a Brownian particle, the movements
of which are limited by the length of the chain. The probability density of the ball’s position is resolved by different diffusional
operators — parabolic (including the case with drift), hyperbolic, and fractional. We show how those different approaches
shed light on different aspects of the movement. We also comment on some features of the survival probabilities (which are
ready to be compared with electrophysiological measurements) for issues based on the above operators.
Paper authored by participants of the international conference: International Workshop on Ionic Channels, Szczyrk, Poland,
May 27 – June 01, 2007. Publication cost was covered by the organisers of this meeting. 相似文献
3.
Monika Krasowska Zbigniew J. Grzywna Maria E. Mycielska Mustafa B. A. Djamgoz 《European biophysics journal : EBJ》2009,38(8):1115-1125
The endocytic membrane activities of two human breast cancer cell lines (MDA-MB-231 and MCF-7) of strong and weak metastatic
potential, respectively, were studied in a comparative approach. Uptake of horseradish peroxidase was used to follow endocytosis.
Dependence on ionic conditions and voltage-gated sodium channel (VGSC) activity were characterized. Fractal methods were used
to analyze quantitative differences in vesicular patterning. Digital quantification showed that MDA-MB-231 cells took up more
tracer (i.e., were more endocytic) than MCF-7 cells. For the former, uptake was totally dependent on extracellular Na+ and partially dependent on extracellular and intracellular Ca2+ and protein kinase activity. Analyzing the generalized fractal dimension (D
q
) and its Legendre transform f(α) revealed that under control conditions, all multifractal parameters determined had values greater for MDA-MB-231 compared
with MCF-7 cells, consistent with endocytic/vesicular activity being more developed in the strongly metastatic cells. All
fractal parameters studied were sensitive to the VGSC blocker tetrodotoxin (TTX). Some of the parameters had a “simple” dependence
on VGSC activity, if present, whereby pretreatment with TTX reduced the values for the MDA-MB-231 cells and eliminated the
differences between the two cell lines. For other parameters, however, there was a “complex” dependence on VGSC activity.
The possible physical/physiological meaning of the mathematical parameters studied and the nature of involvement of VGSC activity
in control of endocytosis/secretion are discussed. 相似文献
4.
Wawrzkiewicz A Pawelek K Borys P Dworakowska B Grzywna ZJ 《European biophysics journal : EBJ》2012,41(6):505-526
Several approaches to ion-channel gating modelling have been proposed. Although many models describe the dwell-time distributions correctly, they are incapable of predicting and explaining the long-term correlations between the lengths of adjacent openings and closings of a channel. In this paper we propose two simple random-walk models of the gating dynamics of voltage and Ca(2+)-activated potassium channels which qualitatively reproduce the dwell-time distributions, and describe the experimentally observed long-term memory quite well. Biological interpretation of both models is presented. In particular, the origin of the correlations is associated with fluctuations of channel mass density. The long-term memory effect, as measured by Hurst R/S analysis of experimental single-channel patch-clamp recordings, is close to the behaviour predicted by our models. The flexibility of the models enables their use as templates for other types of ion channel. 相似文献
5.
The ball and chain mechanism is a widely accepted theory for the inactivation of the Shaker K(+)channel. In this paper we propose a diffusive model that predicts a rate of inactivation that is comparable to the experimental measurements. 相似文献
6.
Fin ZJ Cai Sue Lester Tim Lu Helen Keen Karyn Boundy Susanna M Proudman Anne Tonkin Maureen Rischmueller 《Arthritis research & therapy》2008,10(2):R31
Introduction
The aim of this study was to compare cardiovascular autonomic nervous system function in patients with primary Sj?gren's syndrome (pSS) with that in control individuals, and to correlate the findings with autonomic symptoms and the presence of exocrine secretory dysfunction. 相似文献7.
8.
An important goal in many branches of science, especially in molecular biology and medicine is the quantitative analysis of the structures and their morphology. The morphology can be analyzed in many ways, in particular by the fractal analysis. Apart from the fractal dimension, an important part of the fractal analysis is the lacunarity measurement which, roughly speaking, characterizes the distribution of gaps in the fractal: a fractal with high lacunarity has large gaps. In this paper, we present an extension of the lacunarity measure to objects with nonregular shapes that enables us to provide a successful discrimination of cancer cell lines. The cell lines differ in the shape of vacuole (the gaps in their body) which is perfectly suited for the lacunarity analysis. 相似文献
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