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200 papers

Resonantly-forced oscillatory reaction-diffusion systems can exhibit fronts with complicated interfacial structure separating phase-locked homogeneous states. For values of the forcing amplitude below a critical value the front "explodes"…

Pattern Formation and Solitons · Physics 2009-11-11 Jörn Davidsen , Alexander Mikhailov , Raymond Kapral

Modern observations and models of various astrophysical objects suggest that many of their physical parameters fluctuate substantially at different spatial scales. The rich variety of the emission processes, including Transition Radiation…

Astrophysics · Physics 2007-10-02 Gregory D. Fleishman , Dale E. Gary , Gelu M. Nita

The expansion of ionization fronts in uniform and spherically symmetric power-law density distributions is a well-studied topic. However, in many situations, such as a star formed at the edge of a molecular cloud core, an offset power-law…

Astrophysics · Physics 2009-11-13 S. J. Arthur

We study evolution of pulses propagating through focusing nonlinear media. Small disturbance on the smooth initial non-uniform background leads to formation of the region of strong nonlinear oscillations. We develop here an asymptotic…

Pattern Formation and Solitons · Physics 2022-03-14 A. M. Kamchatnov , D. V. Shaykin

We prove existence, uniqueness, and stability of transition fronts (generalized traveling waves) for reaction-diffusion equations in cylindrical domains with general inhomogeneous ignition reactions. We also show uniform convergence of…

Analysis of PDEs · Mathematics 2009-01-19 Andrej Zlatos

We describe a new methodology to analyze the reionization process in numerical simulations: The evo- lution of the reionization is investigated by focusing on the merger histories of individual HII regions. From the merger tree of ionized…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-10 Jonathan Chardin , Dominique Aubert

We study the diffusion front for a natural two-dimensional model where many particles starting at the origin diffuse independently. It turns out that this model can be described using properties of near-critical percolation, and provides a…

Probability · Mathematics 2009-12-21 Pierre Nolin

Near a parity breaking front bifurcation, small perturbations may reverse the propagation direction of fronts. Often this results in nonsteady asymptotic motion such as breathing and domain breakup. Exploiting the time scale differences of…

patt-sol · Physics 2009-10-30 Aric Hagberg , Ehud Meron , I. Rubinstein , B. Zaltzman

We consider asymptotic problems concerning the motion of interface separating the regions of large and small values of the solution of a reaction-diffusion equation in the media consisting of domains with different characteristics…

Probability · Mathematics 2018-08-29 Mark Freidlin , Leonid Koralov

Recently it has been shown that when an equation that allows so-called pulled fronts in the mean-field limit is modelled with a stochastic model with a finite number $N$ of particles per correlation volume, the convergence to the speed…

Statistical Mechanics · Physics 2009-11-07 Debabrata Panja

This paper explores the potential for statistical epoch of reionization (EOR) measurements using wide field radio observations. New developments in low frequency radio instrumentation and signal processing allow very sensitive EOR…

Astrophysics · Physics 2009-11-10 Miguel F. Morales , Jacqueline Hewitt

We introduce and study a new class of fronts in finite particle number reaction-diffusion systems, corresponding to propagating up a reaction rate gradient. We show that these systems have no traditional mean-field limit, as the nature of…

Statistical Mechanics · Physics 2007-05-23 Elisheva Cohen , David A. Kessler , Herbert Levine

A one-dimensional reaction-diffusion model consisting of two species of particles and vacancies on a ring is introduced. The number of particles in one species is conserved while in the other species it can fluctuate because of creation and…

Statistical Mechanics · Physics 2009-11-13 F H Jafarpour , B Ghavami

We study the planar front solution for a class of reaction diffusion equations in multidimensional space in the case when the essential spectrum of the linearization in the direction of the front touches the imaginary axis. At the linear…

Analysis of PDEs · Mathematics 2017-12-11 Anna Ghazaryan , Yuri Latushkin , Xinyao Yang

Diffusion Models are probabilistic models that create realistic samples by simulating the diffusion process, gradually adding and removing noise from data. These models have gained popularity in domains such as image processing, speech…

Computer Vision and Pattern Recognition · Computer Science 2024-08-21 Md Manjurul Ahsan , Shivakumar Raman , Yingtao Liu , Zahed Siddique

Diffusion probabilistic models excel at sampling new images from learned distributions. Originally motivated by drift-diffusion concepts from physics, they apply image perturbations such as noise and blur in a forward process that results…

Image and Video Processing · Electrical Eng. & Systems 2024-06-07 Pascal Peter

We consider the motion of planar phase-transition fronts in first-order phase transitions of the Universe. We find the steady state wall velocity as a function of a friction coefficient and thermodynamical parameters, taking into account…

Cosmology and Nongalactic Astrophysics · Physics 2012-08-17 Ariel Megevand , Alejandro D. Sanchez

Observations of the end stages of reionization indicate that at $z\approx 5-6$, the ionizing background is not uniform and the mean free path (MFP) changes drastically. As MFP is closely related to the distribution of Lyman Limit Systems…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-02 Jiawen Fan , Huanqing Chen , Camille Avestruz , Affan Khadir

The radio wave propagation channel is central to the performance of wireless communication systems. In this paper, we introduce a novel machine learning-empowered methodology for wireless channel modeling. The key ingredients include a…

Signal Processing · Electrical Eng. & Systems 2024-06-26 Ge Cao , Zhen Peng

The problem of front propagation in flowing media is addressed for laminar velocity fields in two dimensions. Three representative cases are discussed: stationary cellular flow, stationary shear flow, and percolating flow. Production terms…

Chaotic Dynamics · Physics 2009-10-31 M. Abel , A. Celani , D. Vergni , A. Vulpiani