Spectral Regularities of Viscoelastic Parameters of Whole Blood Exposed to Periodic Shear Stress.

Theoretic and experimental study of viscoelastic properties of the whole blood exposed to shear stress was carried out with acoustic resonance method based on the measurement of gain-frequency characteristics of resonating needle in an ARP-01M piezoelectric thromboelastograph (Mednord). The study revealed regularities in the changes of viscoelastic parameters of the whole blood within 0-80 kHz frequency range of shear vibrations. In this frequency range, the elastic (storage) modulus G' reflecting blood elasticity increased with frequency and significantly contributed to the complex viscosity coefficient. The revealed gain-frequency regularities open the vista to employ the acoustic resonance method to determine the viscoelastic parameters of the whole blood and their coagulation-induced changes in the wide frequency range of shear vibrations.

Analysis of Viscoelastic Parameters of Fluids by Low-Frequency Piezoelastography.

Theoretical and experimental analysis of viscoelastic properties of fluids at low oscillating shear stresses was performed. Mathematic approach for calculating the complex coefficient of viscosity on the basis of experimental data on the amplitude-phase characteristics measured by the method of low-frequency piezoelastography was developed. The dependencies of the amplitude and phase shift of the signal recorded by a piezoelectric detector of a ARP-01M Mednord piezoelectric thromboelastograph on the frequency of forced oscillations of a resonator needle in air, water, and glycerin at fixed temperature of 37°C were studied. It was found that with increasing fluid viscosity, the resonance frequency of oscillations decreases in comparison with the frequency of oscillations in air.

Electrophysiological Properties of Rat Vestibular Labyrinth and Their Effect on Parameters of Transmitted Voltage Pulses.

We propose a new approach to optimization of electrical stimulation of the vestibular nerve and improving the transfer function of vestibular implant. A mathematical model of the vestibular organ is developed based on its anatomy, the model premises, 3D-analysis of MRI and CT images, and mathematical description of physical processes underlying propagation of alternating electric current across the tissues of vestibular labyrinth. This approach was tested in vitro on the rat vestibular apparatus and had been examined anatomically prior to the development of its mathematical model and equivalent electrical circuit. The experimental and theoretical values of changes of the gain-phase characteristics of vestibular tissues in relation to location of the reference electrode obtained in this study can be used to optimize the electrical stimulation of vestibular nerve.

[Comparative analysis of carotid-subclavian transposition and stenting in case of stenotic damage of subclavian artery].

So carotid-subclavian transposition and stenting are effective and safe methods of correction of occlusive subclavian artery disease. Angioplasty and stenting of the subclavian artery is particularly indicated in patients with high surgical risk. Patients at low risk of surgery is preferred execution carotid-subclavian transposition.