Porosity effect on the linear stability of flow overlying a porous medium.

We study how the stability of a homogeneous incompressible fluid flow over a saturated Brinkman porous medium is affected by a change in porosity. We produce neutral curves using the shooting method in the area of bimodality. When the porosity decreases, the topology of these curves changes because of the interplay between two instability modes.

Sample size determination in the laser-Doppler measurements of skin blood flow.

Pre-study calculations of the required sample size are vital to a large majority of studies. Using the method based on the Monte-Carlo simulations, we have illustrated how the sample size is related to the statistic power value, the significance level, the variability of observations and the minor magnitude of the effect of interest under study. If the study has been already completed, one should not perform any 'post hoc' power calculations.

Comparative study between microvascular tone regulation and rheological properties of blood in patients with type 2 diabetes mellitus.

The aim of the study is to investigate the changes of the skin blood flow responses to cold stress in patients with diabetes mellitus type 2 through wavelet analysis of the peripheral skin temperature oscillations and to estimate their relationship with the blood viscosity values. The amplitudes of the skin temperature pulsations (ASTP) were monitored by "Microtest" device ("FM-Diagnostics", Russia); the whole blood viscosity and the shear stresses were measured by Contraves LS30 viscometer (Switzerland) at a steady flow in 9 healthy subjects and in 30 patients with type 2 diabetes mellitus. Power law and Herschel-Bulkley (HB) equations were applied to describe the blood rheology.

Instability of plane-parallel flow of incompressible liquid over a saturated porous medium.

The linear stability of plane-parallel flow of an incompressible viscous fluid over a saturated porous layer is studied to model the instability of water flow in a river over aquatic plants. The saturated porous layer is bounded from below by a rigid plate and the pure fluid layer has a free, undeformable upper boundary. A small inclination of the layers is imposed to simulate the riverbed slope.

Frequency and temperature dependence of skin bioimpedance during a contralateral cold test.

A study of the α- and β-dispersion of skin bioimpedance dependence on temperature and micro-hemodynamics is presented. The vascular tone changes during the cold test are verified by the wavelet-analysis of skin temperature signals obtained simultaneously with impedance measurements. Thirty three normal healthy subjects of 28  ±  7 years old were entered into the study.