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We consider the rich variety of collective motion patterns emerging when aligning active particles move in the presence of randomly distributed obstacles - representing quenched noise in two dimensions. In order to get insight into the…

Soft Condensed Matter · Physics 2023-02-21 Danial Vahabli , Tamas Vicsek

In this article we consider systems of parallel hard {\it superellipsoids}, which can be viewed as a possible interpolation between ellipsoids of revolution and cylinders. Superellipsoids are characterized by an aspect ratio and an exponent…

Soft Condensed Matter · Physics 2009-11-13 Yuri Martinez-Raton , Enrique Velasco

We consider the isotropic-to-nematic transition in liquid crystals confined to aerogel hosts, and assume that the aerogel acts as a random field. We generally find that self-averaging is violated. For a bulk transition that is weakly…

Statistical Mechanics · Physics 2015-05-19 J. M. Fish , R. L. C. Vink

Ordered, collective motions commonly arise spontaneously in systems of many interacting, active units, ranging from cellular tissues and bacterial colonies to self-propelled colloids and animal flocks. Active phases are especially rich when…

Soft Condensed Matter · Physics 2024-07-15 Madhuvanthi Guruprasad Athani , Daniel A. Beller

We study the low-temperature behavior of a simple cluster-crystal forming system through simulation. The phase behavior is found to be hybrid between the Gaussian core and penetrable sphere models. The system additionally exhibits a series…

Soft Condensed Matter · Physics 2015-03-17 Kai Zhang , Patrick Charbonneau , Bianca M. Mladek

We describe a one-dimensional self-gravitating system derived from the problem of large-scale structure formation in cosmology. Considering small times so that the expansion can be neglected we present a thermodynamical analysis of this…

Astrophysics · Physics 2009-11-11 Patrick Valageas

Supermassive black holes dominate the gravitational potential in galactic nuclei. In these dense environments, stars follow nearly Keplerian orbits and see their orbital planes relax through the potential fluctuations generated by the…

Astrophysics of Galaxies · Physics 2022-07-06 Nathan Magnan , Jean-Baptiste Fouvry , Christophe Pichon , Pierre-Henri Chavanis

Nonequilibrium steady states of vibrated inelastic frictionless spheres are investigated in quasi-two-dimensional confinement via molecular dynamics simulations. The phase diagram in the density-amplitude plane exhibits a fluidlike…

Soft Condensed Matter · Physics 2019-02-13 Thomas Schindler , Sebastian C. Kapfer

Nematic elastomers do not show the discontinuous, first-order, phase transition that the Landau-De Gennes mean field theory predicts for a quadrupolar ordering in 3D. We attribute this behavior to the presence of network crosslinks, which…

Soft Condensed Matter · Physics 2009-11-11 L. Petridis , E. M. Terentjev

A first order phase transition usually proceeds by nucleating bubbles of the new phase which then rapidly expand. In confining gauge theories with a gravity dual, the deconfined phase is often described by a black hole. If one starts in…

High Energy Physics - Theory · Physics 2010-10-27 Gary T. Horowitz , Matthew M. Roberts

We undertake a systematic numerical exploration of self-organized states in a deterministic model of interacting self-propelled particles in two dimensions. In the process, we identify various types of collective motion, namely, disordered…

Statistical Mechanics · Physics 2015-03-19 Jihad Touma , Amer Shreim , Leonid Klushin

Using a Ginzburg-Landau model, we study the phase transition behavior of compressible Ising systems at constant volume by varying the temperature $T$ and the applied magnetic field $h$. We show that two phases can coexist macroscopically in…

Materials Science · Physics 2009-11-13 Akira Onuki , Akihiko Minami

As rotating neutron stars slow down, the pressure and the density in the core region increase due to the decreasing centrifugal forces and phase transitions may occur in the center. We extract the analytic behavior near the critical angular…

Astrophysics · Physics 2008-11-26 H. Heiselberg , M. Hjorth-Jensen

We study a simple model of a nematic liquid crystal made of parallel ellipsoidal particles interacting via a repulsive Gaussian law. After identifying the relevant solid phases of the system through a careful zero-temperature scrutiny of as…

Soft Condensed Matter · Physics 2009-11-13 Santi Prestipino , Franz Saija

In this paper, gravothermal oscillations are investigated in two-component clusters with a range of different stellar mass ratios and total component mass ratios. The critical number of stars at which gravothermal oscillations first…

Astrophysics of Galaxies · Physics 2015-05-30 Philip G. Breen , Douglas C. Heggie

We report phase separation and liquid-crystal ordering induced by scalar activity in a system of Soft Repulsive Spherocylinders (SRS) of aspect ratio $L/D = 5 $. Activity was introduced by increasing the temperature of half of the SRS…

A numerical solution of Einstein field equations for a spherical symmetric and stationary system of identical and auto-gravitating particles in phase transition is presented. The fluid possess a perfect fluid energy momentum tensor, and the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Jose D. Polanco , Patricio S. Letelier , Maximiliano Ujevic

We study a collection of self-propelled polar particles on a two-dimensional substrate with birth and death. We introduce a minimal lattice model for the system using active Ising spins, where each particle can have two possible…

Soft Condensed Matter · Physics 2022-05-10 Pawan Kumar Mishra , Shradha Mishra

We investigate the ordering properties of vertically-vibrated monolayers of granular cylinders in a circular container at high packing fraction. In line with previous works by other groups, we identify liquid-crystalline ordering behaviour…

Soft Condensed Matter · Physics 2017-05-16 Miguel Gonzalez-Pinto , Florentino Borondo , Yuri Martinez-Raton , Enrique Velasco

A self-interacting polymer can undergo an orientational ordering transition, depending on the magnitude of the nematic interaction. The effect of embedding such a polymer into a flexible surface on this transition is studied on the…

Condensed Matter · Physics 2009-10-28 Rudolf Podgornik