Influence of a sunspot penumbra on the oscillatory regime of neighboring regions

Understanding cell fate selection remains a central challenge in developmental biology. We present a class of simple yet biologically motivated mathematical models for cell differentiation that generically generate oscillations and hence suggest alternatives to the standard framework based on Waddington’s epigenetic landscape. The models allow us to suggest two generic dynamical scenarios that describe the differentiation process. In the first scenario, gradual variation of a single control parameter is responsible for both entering and exiting the oscillatory regime. In the second scenario, two control parameters vary: one responsible for entering, and the other for exiting the oscillatory regime. We analyse the standard repressilator and four variants of it and show the dynamical behaviours associated with each scenario. We present a thorough analysis of the associated bifurcations and argue that gene regulatory networks with these repressilator-like characteristics are promising candidates to describe cell fate selection through an oscillatory process.

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The oscillatory longwave Marangoni convection in a thin film heated from below

SN Applied Sciences ◽

10.1007/s42452-021-04764-5 ◽

2021 ◽

Vol 3 (10) ◽

Author(s):

Anna Samoilova ◽

Alexander Nepomnyashchy

Keyword(s):

Thin Film ◽

Free Surface ◽

Large Scale ◽

Marangoni Convection ◽

Thin Liquid Film ◽

Stationary Regime ◽

Oscillatory Regime ◽

Oscillatory Flows ◽

The Past ◽

Heating From Below

Abstract A novel type of Marangoni convection was predicted theoretically a decade ago. The thin liquid film atop a substrate of low thermal conductivity was considered. In the case of heating from below, the Marangoni convection emerges not only in a conventional stationary regime, but also as oscillatory flows. Specifically, the oscillatory Marangoni convection emerges if (1) the heat flux from the free surface is small, and (2) the large-scale deformation of the free surface is allowed. During the past decade, this novel Marangoni convection was detected and investigated in several other theoretical works. The review discusses the recent achievements in studying the oscillatory Marangoni convection in a thin film heated from below. The guiding data for observation of the oscillatory regime are also provided.

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The Dynamical Transition to Step-Flow Growth During Homoepitaxy of GaAs (001)

MRS Proceedings ◽

10.1557/proc-312-15 ◽

1993 ◽

Vol 312 ◽

Cited By ~ 1

Author(s):

B. G. Orr ◽

J. Sudijono ◽

M. D. Johnson

Keyword(s):

Scanning Tunneling Microscope ◽

Molecular Beam ◽

Scanning Tunneling ◽

Oscillatory Regime ◽

Step Flow ◽

Microscope Images ◽

Step Density ◽

Step Flow Growth ◽

Direct Correspondence ◽

Density Results

AbstractThe evolution of surface morphology of molecular-beam-epitaxy-grown GaAs (001) has been studied by scanning tunneling microscope. Images show that in the early stages of deposition the morphology oscillates between one -with twodimensional nucleation and coalescing islands, i.e. flat terraces. After the initial oscillatory regime, the system evolves to a dynamical steady state. This state is characterized by a constant step density. As such, the growth mode can be called a generalized step flow. Comparison with RHEED shows that there is a direct correspondence between the surface step density and the RHEED specular intensity. An increase in step density results in a decrease in specular intensity. Additionally, further deposition beyond 120 monolayers (up to 1450 monolayers) display a slowly increasing surface roughness.

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The Formation of a Sunspot Penumbra Sector in Active Region NOAA 12574

The Astrophysical Journal ◽

10.3847/1538-4357/aab6b0 ◽

2018 ◽

Vol 857 (1) ◽

pp. 21 ◽

Cited By ~ 2

Author(s):

Qiaoling Li ◽

Xiaoli Yan ◽

Jincheng Wang ◽

DeFang Kong ◽

Zhike Xue ◽

...

Keyword(s):

Active Region ◽

Active Region Noaa ◽

Region Noaa ◽

Sunspot Penumbra

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Simulation of Natural Convection around an Inclined Heating Triangular Cylinder Using Lattice Boltzmann Method: On the Stabilization of the Oscillatory Regime by Using Nanoparticles

High Temperature ◽

10.1134/s0018151x20360043 ◽

2020 ◽

Vol 58 (6) ◽

pp. 852-863

Author(s):

M. El Abdallaoui ◽

A. Amahmid ◽

M. Hasnaoui ◽

I. Pop

Keyword(s):

Natural Convection ◽

Lattice Boltzmann Method ◽

Lattice Boltzmann ◽

Oscillatory Regime ◽

Boltzmann Method

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The Rayleigh–Bénard problem in intermediate bounded domains

Journal of Fluid Mechanics ◽

10.1017/s0022112093002186 ◽

1993 ◽

Vol 254 ◽

pp. 375-400 ◽

Cited By ~ 20

Author(s):

F. Stella ◽

G. Guj ◽

E. Leonardi

Keyword(s):

Flow Pattern ◽

Quantitative Comparison ◽

Flow Structures ◽

Bounded Domains ◽

Oscillatory Regime ◽

Rectangular Container ◽

Two Dimensional Flow ◽

Convection Rolls ◽

Rayleigh Benard Convection ◽

Rayleigh Benard

The stationary instabilities of flow patterns associated with Rayleigh–Bénard convection in a 3 × 1 × 9 rectangular container are extensively investigated by numerical simulation. Two types of spatial instabilities of the base convection rolls are predicted in the transition from steady two-dimensional flow to the unsteady oscillatory regime; these instabilities depend on the Prandtl number. For Pr = 0.71 the soft-roll instability is found at moderate Rayleigh number Ra. The results obtained confirm the importance of this flow pattern as a continuous mechanism for steady transition from one wavenumber to another. For Pr = 15, cross-roll instability is obtained, which at larger Ra leads to bimodal convection. For this value of Pr the soft-roll flow pattern is found at intermediate Ra. At higher Ra a new flow structure in which cross-rolls are superimposed on the soft roll is obtained. The effects of the various flow structures on the heat transfer are given. A quantitative comparison with previous experimental and theoretical findings is also presented and discussed.

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