Influence Of Internal Noise Research Articles

Kinetic analysis of p53 gene network with time delays and PIDD

p53 kinetics plays a key role in regulating cell fate. Based on the p53 gene regulatory network composed by the core regulatory factors ATM, Mdm2, Wip1, and PIDD, the effect of the delays in the process of transcription and translation of Mdm2 and Wip1 on the dynamics of p53 is studied theoretically and numerically. The results show that these two time delays can affect the stability of the positive equilibrium. With the increase of delays, the dynamics of p53 presents an oscillating state. Further, we also study the effects of PIDD and chemotherapeutic drug etoposide on the kinetics of p53. The model indicates that (i) PIDD low-level expression does not significantly affect p53 oscillatory behavior, but high-level expression could induce two-phase kinetics of p53; (ii) Too high and too low concentration of etoposide is not conducive to p53 oscillation. These results are in good agreement with experimental findings. Finally, we consider the influence of internal noise on the system through Binomial [Formula: see text]-leap algorithm. Stochastic simulations reveal that high-intensity noise completely destroys p53 dynamics in the deterministic model, whereas low-intensity noise does not alter p53 dynamics. Interestingly, for the stable focus, the internal noise with appropriate intensity can induce quasi-limit cycle oscillations of the system. Our work may provide the useful insights for the development of anticancer therapy.

The Influence of Internal Noise on Electronic Current Transformer Error

We describe the effect of noise generated by electric circuits in a measuring digital electronic current transformer on measurement accuracy. It is shown that the systematic error is affected by the parameters of the analog anti-aliasing filter, while the random error component is affected by the parameters of the digital averaging filter.

Explicit calcium bursting stochastic resonance

In the present work the influence of internal noise resulting from small cell volume on bursting calcium oscillations is studied. With the internal noise switched on, the center of the main peak in the PSD (power spectrum density) was modified by internal noise. With increasing of the cell volume, the calculated signal-to-noise ratio (SNR) undergoes a maximum, which is referred in the present work as explicit bursting stochastic resonance. In addition, another quantity, the correlation time is used to measure the coherence of bursting oscillations. We demonstrate that the correlation time of the oscillations also exhibits a maximum at a certain cell volume.

Constructive Role of Internal Noise for the Detection of Weak Stimulation in a Coupled Biological Cell System

By constructing a mesoscopic stochastic model for intracellular calcium oscillations in coupled cell system, we investigated the influence of internal noise on the detection of weak stimulation using the chemical Langevin equation (CLE). We found that an optimal cell size V existed for a coupled cell chain length N and an optimal value of N existed for a given cell size V. At these values, the collective calcium oscillations showed the best performance, indicating the occurrence of"system size resonance (SSR)"or"internal noise stochastic resonance (INSR)". And such a phenomenon was robust to the coupling strength. Living cells may have learned to exploit the internal noise to detect weak stimulation via the mechanism of INSR, and then encode information to specifically regulate distinct cellular functions. It is interesting to note that the optimal cell size is always present at V≈103 μm3, which is close to the real living cell size in vivo. Since the internal noise in living systems can not be ignored and the systems may often encounter weak stimulations, our findings might have significance for stimulation detecting processes in living systems.

System Size Resonance Associated with Canard Phenomenon in a Biological Cell System

The influence of internal noise on the calcium oscillations is studied. It is found that stochastic calcium oscillations occur when the internal noise is considered, while the corresponding deterministic dynamics only yields a steady state. Also, the performance of such oscillations shows two maxima with the variation of the system size, indicating the occurrence of system size resonance. This behavior is found to be intimately connected with the canard phenomenon. Interestingly, it is also found that one of the optimal system sizes matches well with the real cell size, and such a match is robust to the variation of the control parameters.

Effects of internal noise for rate oscillations during CO oxidation on platinum surfaces

We have studied the influence of internal noise on the reaction rate oscillation during carbon-monoxide oxidation on single crystal platinum surfaces using chemical Langevin equations. Considering that the surface is divided into small well-mixed cells, we have focused on the dynamic behavior inside a single cell. Internal noise can induce rate oscillations and the performance of the stochastic rate oscillations shows double maxima with the variation of the internal noise intensity, demonstrating the occurrence of internal noise coherent biresonance. The relationship between such a phenomenon with the deterministic bifurcation features of the system is also discussed.

Internal noise enhanced detection of hormonal signal through intracellular calcium oscillations

A variety of cell types respond to extracellular hormonal signals by repetitive intracellular calcium spikes. Here, by constructing a mesoscopic stochastic model for intracellular calcium oscillations in hepatocytes, we have investigated the influence of internal noise on the detection of sub-threshold hormonal signals using chemical Langevin equation (CLE) and Poisson approximation. It is found that stochastic calcium spikes appear when the internal noise is considered, and the regularity of the spike train undergoes a maximum with the variation of the internal noise level, indicating the occurrence of internal noise stochastic resonance (INSR). Since the magnitude of the internal noise is changed via the variation of the system size, the INSR also represents itself a kind of system size resonance.

Internal noise stochastic resonance in CO oxidation on nm-sized palladium particles

Based on a stochastic mesoscopic model, the influence of internal noise on the oscillatory kinetics of the catalytic oxidation of CO on nm-sized palladium particles is studied, using the chemical Langevin equations, Poisson approximation algorithm, and exact stochastic simulation algorithm. The reaction rate oscillations are of stochastic nature due to considerable internal noise in such mesoscopic systems. It is found that the performance of the stochastic oscillations undergoes a maximum with the variation of internal noise level for a given CO partial pressure, which demonstrates the occurrence of internal noise stochastic resonance. This phenomenon implies that optimal internal noise would favor the reaction rate oscillation of CO oxidation on nm particles. Such a phenomenon is robust to the change of external parameters, such as CO pressures.

STOCHASTIC SYNCHRONIZATION OF ELECTRORECEPTORS IN PADDLEFISH

We studied synchronization of electrosensitive cells of the paddlefish by means of electrophysiological experiments. We found that primary afferents of the paddlefish are represented by noisy nonlinear oscillators. Different types of phase locked regimes are observed. The influence of internal noise is discussed.