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In this paper we give, for the first time, a complete description of the dynamics of tilted spatially homogeneous cosmologies of Bianchi type II. The source is assumed to be a perfect fluid with equation of state $p = (\gamma -1) \mu$,…

General Relativity and Quantum Cosmology · Physics 2015-06-25 C. G. Hewitt , R. Bridson , J. Wainwright

In this work we explore the quantum Bianchi type IX-model, its semi-classical features, and its relevance in early cosmology to tentatively explain inflation and production of primordial structures. We specially focus on the analytical and…

General Relativity and Quantum Cosmology · Physics 2023-02-10 Jaime de Cabo Martin

By applying a standard solution generating technique, we transform an arbitrary vacuum Mixmaster solution on $S^3 \times {\bf R}$ to a new solution which is spatially inhomogeneous. We thereby obtain a family of exact, spatially…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Beverly K. Berger , Vincent Moncrief

Using the Geroch transformation we obtain the first example of an exact stiff fluid spike solution to the Einstein field equations in a closed form exhibiting a spacelike $G_1$ group of symmetries (i.e., with a single isometry). This new…

General Relativity and Quantum Cosmology · Physics 2016-10-17 Alan Coley , Daniele Gregoris , Woei Chet Lim

In this paper, we further explore the local-to-global approach for expansion of simplicial complexes that we call local spectral expansion. Specifically, we prove that local expansion in the links imply the global expansion phenomena of…

Combinatorics · Mathematics 2018-03-06 Izhar Oppenheim

In this paper, the crucial phenomenon of the expansion of the universe has been discussed. For this purpose, we study the vacuum solutions of Bianchi types $I$ and $V$ spacetimes in the framework of $f(R)$ gravity. In particular, we find…

General Relativity and Quantum Cosmology · Physics 2010-05-07 M. Sharif , M. Farasat Shamir

We introduce an alternative to the method of matched asymptotic expansions. In the "traditional" implementation, approximate solutions, valid in different (but overlapping) regions are matched by using "intermediate" variables. Here we…

Fluid Dynamics · Physics 2017-01-23 Luiz M. Faria , Rodolfo R. Rosales

Self-consistent system of spinor, scalar and BI gravitational fields is considered. Exact solutions to the field equations in terms of volume scale of the BI metric are obtained. Einstein field equations in account of the cosmological…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Bijan Saha , Todor Boyadjiev

We construct new classes of the dynamical black hole solutions in five or higher dimensional Einstein-Maxwell theory, coupled to a dilaton field, in the presence of arbitrary cosmological constant. The dilaton field interacts non-trivially…

General Relativity and Quantum Cosmology · Physics 2025-01-15 B. H. Fahim , A. M. Ghezelbash

In this paper we obtain the existence of global attractors for the dynamical systems generated by weak solution of the three-dimensional Navier-Stokes equations with damping. We consider two cases, depending on the values of the parameters…

Analysis of PDEs · Mathematics 2025-07-30 Daniel Pardo , José Valero , Ángel Giménez

simpcomp is an extension to GAP, the well known system for computational discrete algebra. It allows the user to work with simplicial complexes. In the latest version, support for simplicial blowups and discrete normal surfaces was added,…

Combinatorics · Mathematics 2019-10-24 Felix Effenberger , Jonathan Spreer

In a recent paper, we introduced a new way of treating systems of compounded angular momentum. We obtained the probability amplitudes for measurements on the systems and used these to derive the matrix treatment of compounded spin. However,…

Quantum Physics · Physics 2007-05-23 Habatwa Vincent Mweene

We consider a 2D infinite channel domain with an incompressible fluid satisfying the so-called dynamic slip boundary condition on the (part of the) boundary. Introducing an exhaustion by a sequence of bounded sub-domains of the whole…

Analysis of PDEs · Mathematics 2024-08-26 Michael Zelina

Technological advancements have enabled the recording of spiking activities from large neuron ensembles, presenting an exciting yet challenging opportunity for statistical analysis. This project considers the challenges from a common type…

Applications · Statistics 2024-04-05 Zitong Zhang , Shizhe Chen

One of the major problems for maximum likelihood estimation in the well-established directional models is that the normalising constants can be difficult to evaluate. A new general method of "score matching estimation" is presented here on…

Statistics Theory · Mathematics 2016-04-29 Kanti V Mardia , John T Kent , Arnab K Laha

The dissipative wave equation with a critical quintic nonlinearity in smooth bounded three dimensional domain is considered. Based on the recent extension of the Strichartz estimates to the case of bounded domains, the existence of a…

Analysis of PDEs · Mathematics 2013-09-25 Varga Kalantarov , Anton Savostianov , Sergey Zelik

In a spiked population model, the population covariance matrix has all its eigenvalues equal to units except for a few fixed eigenvalues (spikes). Determining the number of spikes is a fundamental problem which appears in many scientific…

Statistics Theory · Mathematics 2011-04-18 Damien Passemier , Jian-Feng Yao

We investigate whether there are attractor equations for N=1 flux vacua in generalized compactifications. We fill a gap in the existing literature by verifying analytically that the recently proposed susy attractors, for type IIB CY(3)…

High Energy Physics - Theory · Physics 2009-01-16 Lilia Anguelova

A model "remarkable" fin equation is singled out from a class of nonlinear (1+1)-dimensional fin equations. For this equation a number of exact solutions are constructed by means of using both classical Lie algorithm and different modern…

Mathematical Physics · Physics 2008-11-18 R. O. Popovych , C. Sophocleous , O. O. Vaneeva

This paper develops a method for obtaining guaranteed outer approximations for global attractors of continuous and discrete time nonlinear dynamical systems. The method is based on a hierarchy of semidefinite programming problems of…

Optimization and Control · Mathematics 2023-10-05 Corbinian Schlosser , Milan Korda
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