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We propose a novel approach to modeling cell migration in an anisotropic environment with biochemical heterogeneity and interspecies interactions, using as a paradigm glioma invasion in brain tissue under the influence of hypoxia-triggered…

Tissues and Organs · Quantitative Biology 2021-04-14 Anne Dietrich , Niklas Kolbe , Nikolaos Sfakianakis , Christina Surulescu

We study infinite server queues driven by Cox processes in a fast oscillatory random environment. While exact performance analysis is difficult, we establish diffusion approximations to the (re-scaled) number-in-system process by proving…

Probability · Mathematics 2021-08-31 Harsha Honnappa , Yiran Liu , Samy Tindel , Aaron Yip

A hallmark of a plethora of intracellular signaling pathways is the spatial separation of activation and deactivation processes that potentially results in precipitous gradients of activated proteins. The classical Metabolic Control…

Analysis of PDEs · Mathematics 2007-05-23 Mark A. Peletier , Hans V. Westerhoff , Boris N. Kholodenko

We report on a molecular simulation method which captures the self-assembly of cationic lipid-DNA (CL-DNA) gene delivery complexes. Computational efficiency required for large length- and time-scale simulations is achieved through a…

Soft Condensed Matter · Physics 2007-05-23 Oded Farago , Niels Grønbech-Jensen , Philip Pincus

We consider Reaction-Diffusion systems on $\mathbb{R}$, and prove diffusive mixing of asymptotic states $u_0(kx - \phi_{\pm}, k)$, where $u_0$ is a periodic wave. Our analysis is the first to treat arbitrarily large phase-offsets $\phi_d =…

Analysis of PDEs · Mathematics 2016-10-21 Sameer Iyer , Bjorn Sandstede

A multi-phase-field model for the description of the discontinuous precipitation reaction is formulated which takes into account surface diffusion along grain boundaries and interfaces as well as volume diffusion. Simulations reveal that…

Materials Science · Physics 2008-09-04 Lynda Amirouche , Mathis Plapp

In this article, we design Asymptotic-Preserving Particle-In-Cell methods for the Vlasov-Maxwell system in the quasi-neutral limit, this limit being characterized by a Debye length negligible compared to the space scale of the problem.…

Plasma Physics · Physics 2015-09-15 Pierre Degond , Fabrice Deluzet , David Doyen

We discovered a class of self-similar solutions in nonlinear models describing the formation of morphogen gradients, the concentration fields of molecules acting as spatial regulators of cell differention in developing tissues. These models…

Quantitative Methods · Quantitative Biology 2015-05-28 Cyrill B. Muratov , Peter V. Gordon , Stanislav Y. Shvartsman

We model chaotic diffusion, in a symplectic 4D map by using the result of a theorem that was developed for stochastically perturbed integrable Hamiltonian systems. We explicitly consider a map defined by a free rotator (FR) coupled to a…

Chaotic Dynamics · Physics 2015-06-17 Martín F. Mestre , Armando Bazzani , Pablo M. Cincotta , Claudia M. Giordano

In this paper, we study quasi-stationarity for a large class of Kolmogorov diffusions. The main novelty here is that we allow the drift to go to $- \infty$ at the origin, and the diffusion to have an entrance boundary at $+\infty$. These…

Many cellular and subcellular biological processes can be described in terms of diffusing and chemically reacting species (e.g. enzymes). Such reaction-diffusion processes can be mathematically modelled using either deterministic…

Biological Physics · Physics 2015-06-26 Radek Erban , S. Jonathan Chapman

Particle-based stochastic reaction-diffusion (PBSRD) models are a popular approach for studying biological systems involving both noise in the reaction process and diffusive transport. In this work we derive coarse-grained deterministic…

Probability · Mathematics 2021-09-02 Samuel A. Isaacson , Jingwei Ma , Konstantinos Spiliopoulos

Stochastic chemical systems with diffusion are modeled with a reaction-diffusion master equation. On a macroscopic level, the governing equation is a reaction-diffusion equation for the averages of the chemical species. On a mesoscopic…

Numerical Analysis · Mathematics 2009-03-06 Stefan Engblom , Lars Ferm , Andreas Hellander , Per Lötstedt

We introduce a simplified model of physiological coughing or sneezing, in the form of a thin liquid layer subject to a rapid (30 m/s) air stream. The setup is simulated using the Volume-Of-Fluid method with octree mesh adaptation, the…

Fluid Dynamics · Physics 2021-01-19 Cesar Pairetti , Raphaël Villiers , Stéphane Zaleski

Using a non-perturbative method developed in a previous work (paper II), we derive the probability distribution $P(\delta_R)$ of the density contrast within spherical cells in the quasi-linear regime for some non-Gaussian initial…

Astrophysics · Physics 2009-11-06 P. Valageas

Score-based Generative Models (SGMs) have demonstrated exceptional synthesis outcomes across various tasks. However, the current design landscape of the forward diffusion process remains largely untapped and often relies on physical…

Machine Learning · Computer Science 2023-10-13 Kushagra Pandey , Stephan Mandt

We propose a new semi-Lagrangian Vlasov-Poisson solver. It employs elements of metric to follow locally the flow and its deformation, allowing one to find quickly and accurately the initial phase-space position $Q(P)$ of any test particle…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-02 S. Colombi , C. Alard

In this letter we present a measurement of the phase-space density distribution (PSDD) of ultra-cold \Rb atoms performing 1D anomalous diffusion. The PSDD is imaged using a direct tomographic method based on Raman velocity selection. It…

Atomic Physics · Physics 2017-08-16 Gadi Afek , Jonathan Coslovsky , Arnaud Courvoisier , Oz Livneh , Nir Davidson

Generative models, such as GANs and diffusion models, have been used to augment training sets and boost performances in different tasks. We focus on generative models for cell detection instead, i.e., locating and classifying cells in given…

Computer Vision and Pattern Recognition · Computer Science 2024-09-06 Chen Li , Xiaoling Hu , Shahira Abousamra , Meilong Xu , Chao Chen

We consider a special type of fast reaction-diffusion systems in which the coefficients of the reaction terms of the two substances are much larger than those of the diffusion terms while the diffusive motion to the substrate is negligible.…

Numerical Analysis · Mathematics 2024-04-30 Yu Zhao , Zhennan Zhou