Noise Enhanced Stability in Fluctuating Metastable States

We derive general equations for the nonlinear relaxation time of Brownian diffusion in randomly switching potential with a sink. For piece-wise linear dichotomously fluctuating potential with metastable state, we obtain the exact average lifetime as a function of the potential parameters and the noise intensity. Our result is valid for arbitrary white noise intensity and for arbitrary fluctuation rate of the potential. We find noise enhanced stability phenomenon in the system investigated: the average lifetime of the metastable state is greater than the time obtained in the absence of additive white noise. We obtain the parameter region of the fluctuating potential where the effect can be observed. The system investigated also exhibits a maximum of the lifetime as a function of the fluctuation rate of the potential.Comment: 7 pages, 5 figures, to appear in Phys. Rev. E vol. 69 (6),200

An asynchronized synchronous machine to control a flexible grid operation

In this paper, a system of two asynchronized synchronous machines is proposed to control a power-flow in a meshed grid of 220/500 kV and a control algorithm, including a system parameterization guide. The proposed system is supposed to qualitatively affect the parameters of steady-state modes and shirt-circuit-caused transient processes and to increase the transfer capacity of the grid. Wherein, this double-fed synchronous machines complex allows for a significant increase in the power quality and reliability within the grid’s normal operation. Long-term dynamics is considered. As a result, it is shown that the proposed system parametrization provides a significant decrease in active power fluctuations and power system swinging

An asynchronized synchronous machine to control a flexible grid operation

In this paper, a system of two asynchronized synchronous machines is proposed to control a power-flow in a meshed grid of 220/500 kV and a control algorithm, including a system parameterization guide. The proposed system is supposed to qualitatively affect the parameters of steady-state modes and shirt-circuit-caused transient processes and to increase the transfer capacity of the grid. Wherein, this double-fed synchronous machines complex allows for a significant increase in the power quality and reliability within the grid’s normal operation. Long-term dynamics is considered. As a result, it is shown that the proposed system parametrization provides a significant decrease in active power fluctuations and power system swinging.</jats:p

Pathogenic Escherichia coli change the adhesion between neutrophils and endotheliocytes in the experimental bacteremia model

Septicemia caused by gram-negative bacteria is characterized by high death rate due to the endotoxin release. Since the septicemia depends not only on biochemical aspects of interactions in the system bloodstream, the study of mechanical interactions is also important. Using a model of experimental septicemia caused by E. coli, a hyperproduction of integrins CD11a and CD11b by neutrophils was shown, but this did not lead to the establishment of strong adhesion contacts between endothelial cells and neutrophils. On the contrary, adhesion force and work, as assessed by FS spectroscopy, were statistically significantly reduced in the presence of bacteria. It has also been shown that exposure to the pathogenic strain E. coli 321 increases the stiffness of the membrane-cytoskeleton complex of endothelial cells and bacteria significantly change their morphology on long-term observation. At the same time, we observed the death of neutrophils by apoptosis. Thus, it was shown that besides lipopolysaccharide release there are other pathogenic factors of E. coli: decrease in the interaction between neutrophil and endothelial cell caused by an increase of the endothelial cell rigidity and apoptotic death of neutrophils probably as a result of adhesins and exotoxin effects. Obtained results should be taken in mind during the therapy of septicemia