arXiv subjects

R. K. Brojen Singh

Publications and source records attributed to R. K. Brojen Singh.

43 records · Page 3Linked to original sources

arXiv2014

The co-existence of states in p53 dynamics driven by miRNA

The regulating mechanism of miRNA on p53 dynamics in p53-MDM2-miRNA model network incorporating reactive oxygen species (ROS) is studied. The study shows that miRNA drives p53 dynamics at various states, namely, stabilized states and oscillating states (damped and sustain oscillation). We found the co-existence of these states within certain range of the concentartion level of miRNA in the system. This co-existence in p53 dynamics is the signature of the system's survival at various states, normal, activated and apoptosis driven by a constant concentration of miRNA.

q-bio.MN↗

arXiv2011

Numerical detection of stochastic to deterministic transition

We present the numerical estimation of noise parameter induced in the dynamics of the variables by random particle interactions involved in the stochastic chemical oscillator and use it as order parameter to detect the transition from stochastic to deterministic regime. In stochastic regime, this noise parameter is found to be increased as system size decreases, whereas, in deterministic regime it remains constant to minimum value as system size increases. This let the transition from fluctuating to fixed limit cycle oscillation as the system goes from stochastic to deterministic transition. We also numerically estimated the strength of the noise parameter involved both in Chemical Langevin equation and Master equation formalisms and found that strength of this parameter is much smaller in the former than the later.

physics.comp-ph↗

arXiv2011

Effect of diffusion of elements on network topology and self-organization

We study the influence of elements diffusing in and out of a network to the topological changes of the network and characterize it by investigating the behavior of probability of degree distribution ($Γ(k)$) with degree $k$. The local memory of the incoming element and its interaction with the elements already present in the network during the growing process significantly affect the network stability which in turn reorganize the network properties. We found that the properties of $Γ(k)$ of this network are deviated from scale free type, where the power law behavior contains a exponentially decay factor supporting earlier reported results of Amaral et.al. \cite{ama} and Newman \cite{new1} and recent statistical analysis results on degree distribution data of some scale free network [11]. Our numerical results also support the behavior of this $Γ(k)$. However, we found numerically the contribution from exponential factor to the $Γ(k)$ to be very weak as compared to the scale free factor showing that the network as a whole carries the scale free properties approximately.

physics.comp-ph↗

arXiv2010

Measurement of phase synchrony of coupled segmentation clocks

The temporal behaviour of segmentation clock oscillations show phase synchrony via mean field like coupling of delta protein restricting to nearest neighbours only, in a configuration of cells arranged in a regular three dimensional array. We found the increase of amplitudes of oscillating dynamical variables of the cells as the activation rate of delta-notch signaling is increased, however, the frequencies of oscillations are decreased correspondingly. Our results show the phase transition from desynchronized to synchronized behaviour by identifying three regimes, namely, desynchronized, transition and synchronized regimes supported by various qualitative and quantitative measurements.

physics.comp-ph↗

arXiv2010

Intercellular synchronization of diffusively coupled astrocytes

We examine the synchrony of the dynamics of localized [Ca^{2+}]_i oscillations in internal pool of astrocytes via diffusing coupling of a network of such cells in a certain topology where cytosolic Ca^{2+} and inositol 1,4,5-triphosphate (IP3) are coupling molecules; and possible long range interaction among the cells. Our numerical results claim that the cells exhibit fairly well coordinated behaviour through this coupling mechanism. It is also seen in the results that as the number of coupling molecular species is increased, the rate of synchrony is also increased correspondingly. Apart from the topology of the cells taken, as the number of coupled cells around any one of the cells in the system is increased, the cell process information faster.

physics.comp-ph↗

arXiv2006

The synchronization of stochastic oscillators

We examine microscopic mechanisms for coupling stochastic oscillators so that they display similar and correlated temporal variations. Unlike oscillatory motion in deterministic dynamical systems, complete synchronization of stochastic oscillators does not occur, but appropriately defined oscillator phase variables coincide. This is illustrated in model chemical systems and genetic networks that produce oscillations in the dynamical variables, and we show that suitable coupling of different networks can result in their phase synchronization.

q-bio.QM↗

arXiv2004

Localization of non-interacting electrons in thin layered disordered systems

Localization of electronic states in disordered thin layered systems with b layers is studied within the Anderson model of localization using the transfer-matrix method and finite-size scaling of the inverse of the smallest Lyapunov exponent. The results support the one-parameter scaling hypothesis for disorder strengths W studied and b=1,...,6. The obtained results for the localization length are in good agreement with both the analytical results of the self-consistent theory of localization and the numerical scaling studies of the two-dimensional Anderson model. The localization length near the band center grows exponentially with b for fixed W but no localization-delocalization transition takes place.

cond-mat.dis-nn↗