Time periodic electroosmotic flow of micropolar fluids through microparallel channel

The time periodic electroosmotic between two infinitely extended microparallel flow of an incompressible micropolar fluid plates is studied. The analytical solutions of the velocity and microrotation are derived under the Debye-Hiickel approximation. The effects of the related dimensionless parameters, e.g., the micropolar parameter, the frequency, the electrokinetic width, and the wall zeta potential ratio of the upper plate to the lower plate, on the electroosmotic velocity and rnicrorotation are investigated. The results show that the amplitudes of the velocity and the volume flow rate will drop to zero when the micropolar parameter increases from 0 to 1. The effects of the electrokinetic width and the frequency on the velocity of the micropolar fluid are similar to those of the Newtonian fluid. However, the dependence of the microrotation on the related parameters mentioned above is complex. In order to describe these effects clearly, the dimensionless microrotation strength and the penetration depth of the microrotation are defined, which are used to explain the variation of the microrotation. In addition, the effects of various parameters on the dimensionless stress tensor at the walls are studied.

Theoretical analysis of equatorial near-inertial solitary waves under complete Coriolis parameters

An investigation of equatorial near-inertial wave dynamics under complete Coriolis parameters is performed in this paper.Starting from the basic model equations of oceanic motions,a Korteweg de Vries equation is derived to simulate the evolution of equatorial nonlinear near-inertial waves by using methods of scaling analysis and perturbation expansions under the equatorial beta plane approximation.Theoretical dynamic analysis is finished based on the obtained Korteweg de Vries equation,and the results show that the horizontal component of Coriolis parameters is of great importance to the propagation of equatorial nonlinear near-inertial solitary waves by modifying its dispersion relation and by interacting with the basic background flow.

Impact of Long-range Desert Dust Transport on Hydrometeor Formation over Coastal East Asia

Model simulations and hydrological reanalysis data for 2007 are applied to investigate the impact of long-range desert dust transport on hydrometeor formation over coastal East Asia. Results are analyzed from Hong Kong and Shanghai, which are two representative coastal cities of East Asia. Long-range desert dust transport impacts mainly spring and summer clouds and precipitation over coastal East Asia. In spring, clouds and precipitation come mainly from large-scale condensation and are impacted mainly by dust from the Gobi, Sahara, and Thar deserts. These desert dusts can participate in the precipitation within and below the clouds. At lower latitudes, the dust particles act mainly as water nuclei. At higher latitudes, they act as both water nuclei and ice nuclei. The effect of Gobi, Sahara, and Thar dust on large-scale clouds and precipitation becomes stronger at higher latitudes. In summer, clouds and precipitation over coastal East Asia come mainly from convection and are impacted mainly by dust from the Taklamakan, Arabian, and Karakum-Kavir deserts. Most Taklamakan dust particles can participate in precipitation within convective clouds as ice nuclei, while Arabian and Karakum-Kavir dust particles participate only as water nuclei in precipitation below the clouds. The effect of Taklamakan dust on convective clouds and precipitation becomes stronger at lower latitudes. Of all the desert dusts, that from the Gobi and Taklamakan deserts has the relatively largest impact. Gobi dust impacts climate change in coastal East Asia by affecting spring water clouds at higher latitudes.

Dynamics of Rossby solitary waves with time-dependent mean flow via Euler eigenvalue model

The investigation on the fluctuations of nonlinear Rossby waves is of great importance for the understanding of atmospheric or oceanic motions.The present paper mainly deals with the well-known atmospheric blocking phenomena through the nonlinear Rossby wave theories and the corresponding methods.Based on the equivalent barotropic potential vorticity model in theβ-plane approximation underlying a weak time-dependent mean flow,the multiscale technique and perturbation approximated methods are adopted to derive a new forced Korteweg-de Vries model equation with varied coefficients(vfKdV)for the Rossby wave amplitude.For a further analytical treatment of the obtained model problem,a special kind of basic flow is adopted.The evolution processes of atmospheric blocking are well discussed according to the given parameters according to the dipole blocking theory.The effects of some physical factors,especially the mean flow,on the propagation of atmospheric blocking are analyzed.

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,Wipl,and PIDD,the effect of the delays in the process of transcription and translation of Mdm2 and Wipl 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 infuence of internal noise on the system through Binomial r-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.

Exploring the influence of microRNA miR-34 on p53 dynamics:a numerical study

The tumor suppressor p53 is at the hub of the cellular DNA damage response network.P53-dependent cell fate decision is inseparable from p53 dynamics.A type of non-coding microRNA miR-34 has the function of enhancing p53 content.An intriguing question arises:How does miR-34 affect p53 kinetics?To address this question,we reconstruct a p53 signal transduction network model containing miR-34.Some experimental phenomena of p53 pulses are reproduced to explain the rationality of the model.The method of numerical bifurcation is used to investigate the effect of miR-34 on p53 kinetics.We point out that appropriate or higher miR-34 transcription rates can prevent DNA-damaged cell proliferation by causing p53 oscillation or high steady-state kinetic behavior,respectively.However,the lack of miR-34 synthesis ability will induce p53 to remain at a low level,and cells cannot respond correctly to DNA damage.These results are well in line with the anti-cancer role of miR-34.Our work sheds light on how miR-34 carries out its tumor-suppressive function from tuning p53 dynamic aspect.

Oscillation and bistable switching dynamical behavior of p53 regulated by PTEN upon DNA damage

The tumor suppressor p53 plays a key regulatory role in the response of cells to various stresses.It have experimentally shown that p53 can exhibit rich dynamic behaviors under DNA damage.In order to study the meticulous mechanism,we construct a coupling model including p53-murine double minute 2(Mdm2)negative feedback loop(NFL)and p53-phosphatase and tensin homolog(PTEN)-Mdm2 positive feedback loop(PFL).By making use of bifurcation analysis and Binomial r-leap algorithm,we confirm that PTEN is a essential condition for p53 oscillation or bistable switching dynamic behaviours.We investigate the p53 dynamics affected by PFL through studying the p53-dependent PTEN synthesis rate.The results suggest that PFL may enrich the dynamic behaviors of the p53 system.This work can promote the understanding of p53 dynamics mediated by PTEN and provide clues for cancer therapy.

Modeling the roles of 14-3-3 σ and Wip1 in p53 dynamics and programmed cell death

The transcription factor p53, also known as the ‘guardian of the genome’ and the ‘gatekeeper’,encodes programmed cell death(apoptosis) information in its dynamics. The anti-cancer protein14-3-3 σ and oncogenic protein Wild-type p53-induced phosphatase 1(Wip1) are both in the p53-murine double minute 2(Mdm2) gene network. However, how these two proteins modulate the dynamics of p53-Mdm2 module and further cell apoptosis remains elusive. Therefore, the authors constructed a relatively comprehensive ordinary differential equation model, taking into account the roles of 14-3-3 σ and Wip1 in p53 dynamics and cell apoptosis. By using numerical methods, we found that p53 exhibits abundant dynamics under the common control of 14-3-3 σand Wip1, and explained the anti-apoptotic effect of Wip1 and the pro-apoptotic effect of 14-3-3σ. By comparing experimental phenomena, we proposed that the p53 oscillation caused by the participation of Wip1 and 14-3-3 σ is closer to the real scene. This paper provides a new insight for p53 dynamics mechanism and apoptosis outcome mediated by Wip1 and 14-3-3 σ, and may be helpful for clinical application.

The nonlinear evolution equation on the shallow water wave

Based on the variation principle, the nonlinear evolution model for the shallow water waves is established. The research shows that Duffing equation can be introduced to the evolution model of water wave with time.