Перегляд за Автор "Kizilova, N."

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A 1000-tube model of human systemic arterial vasculature
(2010) Kizilova, N.
Analysis of stress distribution and leaf blade bending during
(2003) Kizilova, N.
Mechanical factors play an important role in plant tissues growth and development. Plant growth is tightly connected with cell divisions, new cell walls appearing and cell volumes increasing caused by turgor pressure and cell walls loosening and yielding. In biomechanics the plant tissue is considered as integral porous deformable skeleton of cell walls filled with viscous incompressible liquid (intracellular liquid and contents of plant vessels). Xylem sap moves through the xylem vessels, delivers mineral and regulatory components into cells and provides increasing of mass of the solid skeleton. The rate of cell growth is controlled by wall loosening caused by biochemical factors and wall yielding under the influence of the turgor pressure. The tissues consist of elements with different geometry and mechanical properties which are arranged in regular patterns.
Bio-Thermo-Hydro-Mechanics: problems and perspectives
(2011) Kizilova, N.; Samit, R.; Petrov, N.; Szekeres, A.
Biophysical mechanisms of long-distance transport of liquids and signaling in high plants
(2004) Kizilova, N.; Posdniak, L.O.
Wave phenomena have been observed in numerous experiments with whole plants. One of possible mechanisms of the long-distance high-speed signaling in high plants is connected with concentration waves that can propagate through the conducting systems of plants. One-dimensional axisymmetrical stationary flow of a viscous liquid with osmotically active dissolved component through a long thin rigid cylindrical tube is considered as a model of the conducting vessel of the plant. Constant concentrations of the component at the inlet and outlet of the vessel are maintained by the live cells of the vegetative organs of the plant. Nonlinear concentration distribution along the tube and the parabolic velocity profiles are obtained. Propagation of small excitations of concentrations and velocities along the tube is considered. Expression for the wave velocity U is presented. The range U=20-60 m/s is obtained by numerical estimations at wide variations of the parameters within the physiological limits. The time delay in signal transmission in the system root-leaves corresponds to the experimental data. In that way the concentration waves can mediate high-speed transferring of information between the organs of plants.
Common Constructal Principles in Design of Transportation Networks in Plants and Animals
(2008) Kizilova, N.
Common principles of design of long-distance liquid transport in the nature are discussed. Some results of measurements on the preparations and casts of the large systemic and small and medium intraorgan arteries are presented. The regularities between the diameters and the branching angles of the arteries in the bifurcations are revealed. The results of measurements on the conducting systems of plant leaves with different shape, size and type of the vasculature are also presented and compared to the arterial vasculatures. It is found the principles of construction are the same in the transportation networks of animals and higher plants and correspond to the model of optimal branching pipeline that provides liquid delivery at minimal total energy costs. A relationship between the length of the path along any subtree of the pipeline and the corresponding drainage area has been found for the leaf venation. The relationship corresponds to the Hack’s law revealed for the river basins. A model of the steady flow in the pipeline with permeable walls is proposed for the liquid delivery in the leaves. It was found, a balance between the inflow of the liquid into a subtree and its consumption by the cells in the corresponding area leads to the Hack’s law. A comparative study of the hydraulic conductivity of the leaves of different evolutionary age is carried out and validity of the constructal law is shown.
Common principles in construction of biological networks
(2004) Kizilova, N.
In the present paper the statistical data on network geometry of the venation system of Morus alba leaf are presented. The mathematical model of the sap motion in the conducting system of a leaf is proposed. On the base of the solution of an optimization problem the principle of optimal construction of a bifurcation in plant leaf venation that correspond to Murray’s law is obtained.
Computational Approach to Optimal Transport
(2004) Kizilova, N.
Long-distance liquid transport in biosystems is provided by special branching systems of tubes (arteries, veins, plant vessels). Geometry of the systems possesses similar patterns and can be investigated by computer methods of pattern recognition. Here some results on plant leaf venation investigation are presented. The lengths, diameters and branching angles are estimated for the leaves of different shape, size and venation type. The statistical distributions of the measured parameters are similar to the corresponding ones which have been obtained for arterial beds. The both correspond to the model of optimal branching pipeline which provide liquid delivering at minimum total energy consumptions. The biomechanical model of liquid motion in a system consisting of a long thin tube with permeable walls which is embedded into a biological porous medium is considered. The pressure distributions and velocity fields for different geometry of the system are obtained. The main result is when the delivering liquid is completely absorbed by the alive cells in the porous medium the relation between the diameter and the length of the tube and the total volume of the medium which correspond to the measured data is reached.
Computerized posturography for data analysis and mathematical
(2007) Kizilova, N.; Karpinsky, M.
Mechanisms of balance control are investigated on computerized posturography data on vertical two-legged and uncomfortable one-legged stance measured on healthy subjects. Oscillations of the centre of mass in the course of 30 s standing and the corresponding trajectories for a step forward off the force platform have been computed. Spectral analysis of the time series revealed three main harmonics for the studied postures. When a volunteer was balancing standing on one leg, all the harmonics were shifted towards the high frequencies and the sway amplitude was twice increased in comparison with comfortable two-legged vertical stance. Decomposition of the sway trajectories into the rambling and trembling components has been carried out. It was shown that in the course of the one-legged stance the balance control strategy includes ‘scanning’ of the larger area with bigger sway amplitudes in the vicinity of the stable state as compared to two-legged stance. A mathematical model of the body as a multi-link system is considered. Mass and inertia of each body segment and torques in joints are taken into consideration. The calculated own and forced frequencies of the model correspond to the spectral analysis of the posturography data. One-legged stance is proposed as an excellent tool for revealing the balance problems. It is shown that investigation of the oscillations and trajectories of the centre of mass for the step forward off the force platform is perspective for medical diagnostics to distinguish between the spine and joint pathologies.
Construction principles and control over transport systems organization in biological tissues
(2003) Kizilova, N.
The main common principles of the long-range transport systems construction in animal and plant tissues are summarized. The results of measurement of conducting system geometry in Cotinus obovatus leaf are analyzed. It is shown that the principles of design of the conducting systems in animals and higher plants are the same and correspond to the model of optimal pipeline. The mathematical model of fluid motion in the conducting system of the leaf as a mo tion in a branching pipeline with permeable walls is investigated. The cost of a bifurcation of the vessels is analyzed. The hypothesis of the control principle of optimal transport system formation in the growing leaf is discussed. As an example the self-similar conducting system with loops is investigated and compared with some venation systems in plant leaves.
A Detailed Digital Model of the Human Arterial System
(2005) Kizilova, N.
A detailed model of the human circulation is developed. The large systemic arteries are presented by the branching system of straight viscoelastic tubes which corresponds topology of the human circulation. Terminal elements at the outlets of the system are presented by tree-like systems with a given topology (with/without anastomoses) and certain geometrical relations between the lengths and diameters of the vessels of different branching orders and the relation between the maximal total length of the vasculature and diameter of the feeding artery. The relations have been obtained by analysis of the morphometric data. They allow correct calculations of the hydraulic resistance and wave impedance of the arterial beds of different organs. The proposed outflow boundary conditions are more preferable then the Windkessels and the regular tree-like systems because they describe both resonant properties of the intraorgan vasculatures and the distributed sources of the reflected waves. The model describes realistic pressure and flow waves and pressure-flow dependences either in the aorta or in the feeding arteries of the inner organs. The latter underlies possibility of the novel noninvasive diagnostics of the state (normal or pathological) of the intraorgan circulation by noninvasive measuring the wall oscillations and blood flow velocity in any cross-section of the feeding artery of the organ.
Evaluation of human postural balance in quiet standing by direct measurement of human body center of mass acceleration
(2009) Kizilova, N.; Jarmalienė, E.; Šešok, A.; Daunoravičienė, K.; Griškevičius, J.
Present article deals with the evaluation of human postural balance in quiet standing by the direct measuring of center of mass acceleration. Displacements of subjects’ center of mass were determined and trajectories in anterior-posterior-medial-lateral plane were obtained. Comparison of parameters between subjects with stroke and healthy subjects was performed and measurements revealed higher sway amplitudes of subjects with stroke.
Flow distribution and wave propagation in arterial systems with anastomoses
(2005) Kizilova, N.; Sechin, R.P.
Blood flow and wave propagation in the systems of compliant tubes filled with a fluid have been examined as a model of the systemic circulation and the intraorgan arterial networks have been modeled as Windkessel elements or regular treelike branching structures. Real intraorgan vasculatures possess some geometrical regularity and can be modeled as fractal-like trees. Nevertheless blood flow in the real beds and their self-similar models have some differences. Moreover real vasculatures often have anastomoses which provide additional pathways for blood flow and wave propagation and reflection. Arterial beds in the small and large intestine, in stomach and limbs have arterial anastomoses that influence input admittance spectra of the beds in comparison with the tree-like systems.
Load transfer from the growing fibre into the growing medium: application to plant leaf growth
(2007) Kizilova, N.
Biological materials change their mass, shape, and porosity during the growth and possess high strength and durability at general lightweight design. Biological tissues are considered to be inhomogeneous anisotropic multiphase composites reinforced by fibres. A 2D problem of the load transfer from the growing fibre into the growing plate with different own growth rates and viscosity is considered in this paper. Rheology of the growing biological tissue is described by a modified Maxwell model of viscoelastic media. Numerical calculations of the growth velocity and stress fields are carried out. The influence of rheological parameters of two media on the stress–strain state is investigated. It is shown that the stress field may provide local coordinated growth of the fibres and the plate when the rheological parameters of two materials are different and anisotropic growth is observed.
Long-distance liquid transport in plants
(2008) Kizilova, N.
A brief review of the thermodynamic and fluid dynamic problems related to long-distance liquid flow and signalling in plants is presented. Geometrical parameters of the plant leaf venation are measured and the general relationships between the diameters and lengths of the veins, branching angles at the vein bifurcations, and the corresponding drainage areas are obtained. The same relationships had been obtained before for the bifurcations of the pathways in the arterial and bronchial systems of mammals and humans; tree trunks, branches and roots; and river basins. The identity of the principle of design of the transportation systems in the nature can be understood on the concept of optimal networks that provide liquid delivery at total minimal energy costs. The corresponding models of the optimal vessels and branching systems of vessels with impermeable and permeable walls are presented and discussed.
Microimplants, head gears and bracket systems in orthodontic tooth movement: a biomechanical study
(2010) Kizilova, N.; Geramy, A.
A mixture model of differentially growing biological continua
(2010) Kizilova, N.; Stein, A.
Modelling of laminated growing biological materials
(2005) Kizilova, N.; Egorova E.S.
The continued model of the multilayered plate from a growing biological material is presented. Introducing the Airy's stress function the problem is reduced to differential equation of the fourth order. Solution of the problem is obtained for the two- layered plate with a rectangle cross-section. For some relations between the rheological coefficients of the model the governing equations are simplified and the corresponding theoretical estimations are obtained. Numerical calculations of the stress and velocity fields for the model parameters that correspond to the growing plant leaves are presented. Any difference in own growth rates of the adjacent layers leads to stretching of the tempered layer and compressing of the rapidly growing one that results in growth acceleration of the former and growth retardation of the latter. Thus the mechanical stress field can regulate coordinated growth of the laminated biological materials.
Modelling of laminated growing biological materials
(2003) Kizilova, N.
Wave propagation and reflection in the model of branching tree of viscoelastic cylindrical tubes filled with viscous fluid is considered when applied to pulse wave reflection in arterial networks. The dichotomous branching tree and the tree with two anastomoses between the second-order tubes are investigated. Influence of the geometrical and mechanical properties of the tree on the pulse wave propagation and spectral properties of the total admittance of the systems are investigated. It was found out that the admittance has a set of resonant harmonics. Any changes in parameters of microcirculatory bed and in blood rheology cause noticeable alterations of the amplitudes of resonant harmonics and negligible alterations of other harmonics. The set of resonant harmonics is independent of some variations in the tree geometry. The resonant properties of the models with and without anastomoses have some differences, that makes it possible to carry out the diagnosis of the state of inner organs with different types of vasculature. The results substantiate a possibility of the pulse diagnosis of inner organs’ states by observing the amplitudes of the resonant harmonics only, without preliminary knowledge of individual structure of the real vascular bed of an inner organ.
Nature Inspired Optimal Composites
(2010) Kizilova, N.; Szekeres, A.
Novel methods of pulse wave diagnostics based on compression of a superficial artery
(2007) Kizilova, N.
Pulse wave propagation and reflection in the branching systems of viscoelastic tubes and complex resistances as a model of arterial vasculature is considered. Axisymmetric wave motion of a viscous incompressible liquid in the system is investigated in application to the pressure and flow wave propagation in the system. Expression for the input admittance of the system taking into account wave reflection at the end of the tube is obtained. The dependence of the input admittance on the geometrical and mechanical parameters of the system is investigated. It is shown that the parameters of the pressure wave (the modules and phases of different harmonics) at the inlet of the system give information on the state (normal or pathological) of the inner organs. It is shown that after a proper compression (slight or deep) some harmonics can be amplified while the others are attenuated. Based on the theory of resonant harmonics of different inner organs the novel method of pulse wave palpation is proposed. The results are compared to some other methods as separation of the pressure wave into the forward and backward components, estimation of the parameters of the reflected wave and wave-intensity analysis.