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Bianchi models are posited by the BKL picture to be essential building blocks towards an understanding of generic cosmological singularities. We study the behaviour of spatially homogeneous anisotropic vacuum spacetimes of Bianchi type VIII…

General Relativity and Quantum Cosmology · Physics 2016-06-28 Bernhard Brehm

We consider the Bianchi I geometry coupled to several species of comoving barotropic perfect fluids with a linear equation of state in the context of general relativity. The solution of the dynamics can be reduced to a quadrature, which can…

General Relativity and Quantum Cosmology · Physics 2024-10-29 David Brizuela , Sara F. Uria

We consider a five dimensional vacuum cosmology with Bianchi type-IX spatial geometry and an extra non-compact coordinate. Finding a new class of solutions, we examine and rule out the possibility of deterministic chaos. We interpret this…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Paul Halpern

The minisuperspace model of a Bianchi Type I universe with compact spatial sections is investigated. The classical solutions are brought onto a form were the difference between compact and infinite spatial sections are manifest. One of the…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Sigbjorn Hervik

The problem of parameter estimation from a standard vector linear regression equation in the absence of sufficient excitation in the regressor is addressed. The first step to solve the problem consists in transforming this equation into a…

Methodology · Statistics 2022-03-14 Alexey Bobtsov , Bowen Yi , Romeo Ortega , Alessandro Astolfi

In this work, we examine the dynamical aspects of the cosmological Mixmaster model within the framework of non-commutative generalized uncertainty principle (GUP) theories. The theory is formulated classically by introducing a well-defined…

General Relativity and Quantum Cosmology · Physics 2025-04-04 Sebastiano Segreto , Giovanni Montani

The single spike is a rigidly rotating classical string configuration closely related to the giant magnon. We calculate bosonic and fermionic modes of this solution, from which we see that it is not supersymmetric. It can be viewed as an…

High Energy Physics - Theory · Physics 2008-11-26 Michael C. Abbott , Inês Aniceto

A trademark of nonlinear, time-dependent, convection-dominated problems is the spontaneous formation of non-smooth macro-scale features, like shock discontinuities and non-differentiable kinks, which pose a challenge for high-resolution…

Numerical Analysis · Mathematics 2025-10-20 Eitan Tadmor

Bianchi type V bulk viscous fluid cosmological models are investigated. Using a generation technique (Camci {\it et al.}, 2001), it is shown that the Einstein's field equations are solvable for any arbitrary cosmic scale function. The…

General Relativity and Quantum Cosmology · Physics 2009-07-23 Anirudh Pradhan , Vandana Rai , R. S. Singh

Artificial spike-based computation, inspired by models of computations in the central nervous system, may present significant performance advantages over traditional methods for specific types of large scale problems. In this paper, we…

Neurons and Cognition · Quantitative Biology 2007-05-23 Wei Wang , Jean-Jacques E. Slotine

In this paper we consider the existence and stability of multi-spike solutions to the fractional Gierer-Meinhardt model with periodic boundary conditions. In particular we rigorously prove the existence of symmetric and asymmetric two-spike…

Pattern Formation and Solitons · Physics 2023-02-28 Daniel Gomez , Juncheng Wei , Wen Yang

A fundamental example of reaction-diffusion system exhibiting Turing type pattern formation is the Gierer-Meinhardt system, which reduces to the shadow Gierer-Meinhardt problem in a suitable singular limit. Thanks to its applicability in a…

Classical Analysis and ODEs · Mathematics 2026-04-10 Annalisa Iuorio , Christian Kuehn

A well-known diffuse interface model for incompressible isothermal mixtures of two immiscible fluids consists of the Navier-Stokes system coupled with a convective Cahn-Hilliard equation. In some recent contributions the standard…

Analysis of PDEs · Mathematics 2013-01-14 Sergio Frigeri , Maurizio Grasselli , Pavel Krejčí

In this paper we obtain a detailed description of the global and cocycle attractors for the skew-product semiflows induced by the mild solutions of a family of scalar linear-dissipative parabolic problems over a minimal and uniquely ergodic…

Dynamical Systems · Mathematics 2017-12-15 Tomas Caraballo , Jose antonio Lnaga , Rafael Obaya , Ana M. Sanz

We consider the asymptotic behaviour of spatially homogeneous spacetimes of Bianchi type IX close to the singularity (we also consider some of the other Bianchi types, e. g. Bianchi VIII in the stiff fluid case). The matter content is…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Hans Ringstrom

It is believed that soon after the Planck era, spacetime should have a semi-classical nature. In this context we consider quantum fields propagating in a classical gravitational field and study the backreaction of these fields, using the…

General Relativity and Quantum Cosmology · Physics 2011-07-19 Sandro P. Vitenti , Daniel Müller

We find instanton/cosmological solutions with biaxial Bianchi-IX symmetry, involving non-trivial spatial dependence of the $\bbbc P^{1}$- and $\bbbc P^{2}$-sigma-models coupled to gravity. Such manifolds arise in N=1, $d=4$ supergravity…

High Energy Physics - Theory · Physics 2009-11-10 M. M. Akbar , P. D. D'Eath

We apply the dressing method to a string solution given by a static string wrapped around the equator of a three-sphere and find that the result is the single spike solution recently discussed in the literature. Further application of the…

High Energy Physics - Theory · Physics 2010-02-03 Riei Ishizeki , Martin Kruczenski , Marcus Spradlin , Anastasia Volovich

The second order Ordinary Differential Equation which describes the unknown part of the solution space of some vacuum Bianchi Cosmologies is completely integrated for Type III, thus obtaining the general solution to Einstein's Field…

General Relativity and Quantum Cosmology · Physics 2007-05-23 T. Christodoulakis , Petros A. Terzis

We investigate a non-isothermal viscous relaxation of some nonlocal Cahn-Hilliard equations. This perturbation problem generates a family of solution operators, exhibiting dissipation and conservation. The solution operators admit a family…

Analysis of PDEs · Mathematics 2016-07-12 Joseph L. Shomberg