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In this work, we investigate the dynamics of a non-local model describing spontaneous cell polarisation. It consists in a drift-diffusion equation set in the half-space, with the coupling involving the trace value on the boundary. We…

Analysis of PDEs · Mathematics 2011-05-24 Vincent Calvez , Rhoda Hawkins , Nicolas Meunier , Raphael Voituriez

We define a characteristic energy density based on the measurement of the two first moments of the extrinsic injected power smoothed over time. Using the stationarity, we show that this definition characterizes an energy per degrees freedom…

Statistical Mechanics · Physics 2018-07-06 Sebastien Aumaitre , Antoine Naert

In this paper we study the dynamical behaviour of a simple cosmological model defined by a spatially flat Robertson-Walker geometry, conformally coupled with a massive scalar field. We determine a Lyapunov-like function for the non-linear…

General Relativity and Quantum Cosmology · Physics 2009-10-31 M. A. Castagnino H. Giacomini , L. Lara

We discuss some contradictions found in the literature concerning the problem of stability of collisionless spherical stellar systems which are the simplest anisotropic generalization of the well-known polytrope models. Their distribution…

Solar and Stellar Astrophysics · Physics 2015-05-27 E. V. Polyachenko , V. L. Polyachenko , I. G. Shukhman

We investigate the geodesic structure of realistic static and spherically symmetric spacetimes embedding neutron stars in metric $f(R)$ gravity, focusing on the quadratic Starobinsky model $f(R)=aR^2$ with $a<0$. Neutron-star solutions are…

General Relativity and Quantum Cosmology · Physics 2026-03-10 Néstor Rivero González , Álvaro de la Cruz Dombriz , Gonzalo J. Olmo

Computational studies of the thermodynamic properties of materials at the mesoscopic and macroscopic scales -- involving lengths and times of at least $\mu$m and $\mu$s, respectively -- rely on a coarse-graining approximation such that only…

Materials Science · Physics 2026-05-12 Mauro Pulzone , Iñigo Robredo-Magro , Jorge Íñiguez-González

Recently, we have shown that dynamically stable ergostar solutions (equilibrium neutron stars that contain an ergoregion) with a compressible and causal equation of state exist [A. Tsokaros, M. Ruiz, L. Sun, S. L. Shapiro, and K. Ury\=u,…

General Relativity and Quantum Cosmology · Physics 2020-04-08 Antonios Tsokaros , Milton Ruiz , Stuart L. Shapiro

A multispecies, collisionless plasma is modeled by the Vlasov-Poisson system. Assuming that the electric field decays with sufficient rapidity as $t \to\infty$, we show that the velocity characteristics and spatial averages of the particle…

Analysis of PDEs · Mathematics 2022-01-25 Stephen Pankavich

Methods of dynamical systems have been used to study homogeneous and isotropic cosmological models with a varying speed of light (VSL). We propose two methods of reduction of dynamics to the form of planar Hamiltonian dynamical systems for…

General Relativity and Quantum Cosmology · Physics 2008-07-22 Marek Szydlowski , Adam Krawiec

In this letter we apply dynamical system methods to study all evolutional paths admissible for all initial conditions of the FRW cosmological model with a non-minimally coupled to gravity scalar field and a barotropic fluid. We choose…

Astrophysics · Physics 2011-07-13 Marek Szydlowski , Orest Hrycyna

We here construct (large) local and small global-in-time regular unique solutions to the fractional Euler alignment system in the whole space ${\mathbb R}^d$, in the case where the deviation of the initial density from a constant is…

Analysis of PDEs · Mathematics 2018-06-01 Raphaël Danchin , Piotr B. Mucha , Jan Peszek , Bartosz Wróblewski

Modelling the turbulent diffusion of thermal energy, momentum, and metals is required in all galaxy evolution simulations due to the ubiquity of turbulence in galactic environments. The most commonly employed diffusion model, the…

Astrophysics of Galaxies · Physics 2018-12-12 Douglas Rennehan , Arif Babul , Philip F. Hopkins , Romeel Davé , Belaid Moa

Inspired by spatiotemporal observations from satellites of the trajectories of objects drifting near the surface of the ocean in the National Oceanic and Atmospheric Administration's `Global Drifter Program', this paper develops data-driven…

Chaotic Dynamics · Physics 2018-10-19 François Gay-Balmaz , Darryl D. Holm

We discuss two problems which are particularly challenging for approximations in time-dependent density functional theory (TDDFT) to capture: momentum-distributions in ionization processes, and memory-dependence in real-time dynamics. We…

Materials Science · Physics 2010-03-22 Arun K. Rajam , Paul Hessler , Christian Gaun , Neepa T. Maitra

Motivated by the stellar wind ejected from the upper atmosphere (Corona) of a star, we explore a boundary problem of the two-species nonlinear relativistic Vlasov-Poisson systems in the 3D half space in the presence of a constant vertical…

Analysis of PDEs · Mathematics 2024-09-04 Jiaxin Jin , Chanwoo Kim

The Vlasov equation is well known to provide a good description of the dynamics of mean-field systems in the $N \to \infty$ limit. This equation has an infinity of stationary states and the case of {\it homogeneous} states, for which the…

Statistical Mechanics · Physics 2015-03-31 Romain Bachelard , F. Staniscia , Thierry Dauxois , G. De Ninno , S. Ruffo

We derive diffusive macroscopic equations for the particle and energy density of a system whose time evolution is described by a kinetic equation for the one particle position and velocity function f(r,v,t) that consists of a part that…

Statistical Mechanics · Physics 2018-11-14 Pedro L. Garrido , Joel L. Lebowitz

In this paper, we have presented a power law cosmological model and its dynamical system analysis in $f(T,\phi)$ gravity, where $T$ is the torsion scalar and $\phi$ is the canonical scalar field. The two well-motivated forms of the…

General Relativity and Quantum Cosmology · Physics 2025-01-10 S. A. Kadam , Ananya Sahu , S. K. Tripathy , B. Mishra

Non-local reaction-diffusion partial differential equations (PDEs) involving the fractional Laplacian have arisen in a wide variety of applications. One common tool to analyse the dynamics of classical local PDEs near instability is to…

Analysis of PDEs · Mathematics 2024-03-06 Christian Kuehn , Sebastian Throm

In this work an activator-depleted reaction-diffusion system is investigated on polar coordinates with the aim of exploring the relationship and the corresponding influence of domain size on the types of possible diffusion-driven…

Dynamical Systems · Mathematics 2018-01-11 Wakil Sarfaraz , Anotida Madzvamuse