Search results for "QUANTITATIVE METHODS"
showing 10 items of 152 documents
A contribution to the mathematical modeling of immune-cancer competition
2018
Abstract This paper deals with the modeling of interactions between the immune system and cancer cells, in the framework of the mathematical kinetic theory for active particles. The work deepens a previous paper of Belloquid et al. that assumes spatial homogeneity and discrete values of the activity of cancer and immune cells. A number of simulations are made with the aim to investigate how the state of the various cell populations evolves in time depending on the choice of the free parameters.
Inhomogeneous vortex tangles in counterflow superfluid turbulence: flow in convergent channels
2016
Abstract We investigate the evolution equation for the average vortex length per unit volume L of superfluid turbulence in inhomogeneous flows. Inhomogeneities in line density L andincounterflowvelocity V may contribute to vortex diffusion, vortex formation and vortex destruction. We explore two different families of contributions: those arising from asecondorder expansionofthe Vinenequationitself, andthose whichare notrelated to the original Vinen equation but must be stated by adding to it second-order terms obtained from dimensional analysis or other physical arguments.
Discontinuous Galerkin semi-Lagrangian method for Vlasov-Poisson
2011
We present a discontinuous Galerkin scheme for the numerical approximation of the one-dimensional periodic Vlasov-Poisson equation. The scheme is based on a Galerkin-characteristics method in which the distribution function is projected onto a space of discontinuous functions. We present comparisons with a semi-Lagrangian method to emphasize the good behavior of this scheme when applied to Vlasov-Poisson test cases. Une méthode de Galerkin discontinu est proposée pour l’approximation numérique de l’équation de Vlasov-Poisson 1D. L’approche est basée sur une méthode Galerkin-caractéristiques où la fonction de distribution est projetée sur un espace de fonctions discontinues. En particulier, …
Parallel Computing for the study of the focusing Davey-Stewartson II equation in semiclassical limit
2012
The asymptotic description of the semiclassical limit of nonlinear Schrödinger equations is a major challenge with so far only scattered results in 1 + 1 dimensions. In this limit, solutions to the NLS equations can have zones of rapid modulated oscillations or blow up. We numerically study in this work the Davey-Stewartson system, a 2 + 1 dimensional nonlinear Schrödinger equation with a nonlocal term, by using parallel computing. This leads to the first results on the semiclassical limit for the Davey-Stewartson equations.
Graph-based exploration and clustering analysis of semantic spaces
2019
Abstract The goal of this study is to demonstrate how network science and graph theory tools and concepts can be effectively used for exploring and comparing semantic spaces of word embeddings and lexical databases. Specifically, we construct semantic networks based on word2vec representation of words, which is “learnt” from large text corpora (Google news, Amazon reviews), and “human built” word networks derived from the well-known lexical databases: WordNet and Moby Thesaurus. We compare “global” (e.g., degrees, distances, clustering coefficients) and “local” (e.g., most central nodes and community-type dense clusters) characteristics of considered networks. Our observations suggest that …
Statistically validated networks in bipartite complex systems.
2011
Many complex systems present an intrinsic bipartite nature and are often described and modeled in terms of networks [1-5]. Examples include movies and actors [1, 2, 4], authors and scientific papers [6-9], email accounts and emails [10], plants and animals that pollinate them [11, 12]. Bipartite networks are often very heterogeneous in the number of relationships that the elements of one set establish with the elements of the other set. When one constructs a projected network with nodes from only one set, the system heterogeneity makes it very difficult to identify preferential links between the elements. Here we introduce an unsupervised method to statistically validate each link of the pr…
A mathematical model for the therapy of the HIV infection
2005
In this paper we consider the evolution of the HIV infection under a highly effective treatment based on a combination of RTI and/or PI drugs. This is usually modelled with a set of ODEs where the drug efficacy is a constant. In this paper we consider the treatment efficacy as a dynamic variable which evolves during the treatment. To model the dynamics of the drug efficacy we use an evolutive type assumption. The resulting set of ODEs are able to reproduce the typical pattern of the illness evolution under treatment: a period of remission, which can last several years, followed by a progressive recrudescence and a viral rebound.
Insights into genome plasticity of the wine-making bacterium Oenococcus oeni strain ATCC BAA-1163 by decryption of its whole genome.
2008
International audience; Studying genomes of O. oeni strains having opposite oenological aptitudes is important for understanding why this lactic acid bacterium involved in malolactic fermentation is so well adapted to wine. Here, the genome of a strain ATCC BAA-1163, is described and compared with the recently reported genome of the better wine-adapted strain PSU-1. The BAA-1163 genome (8X) was obtained by shotgun sequencing and Phrap assembling. Compact and 62% AT-rich, it consists of a circular 1,792,103-bp chromosome and a 3,948-bp plasmid. It was analysed through a CAAT-Box annotation platform and manually inspected. A total of 51 RNA genes were detected, including two rRNA operons (the…
Probability and algorithmics: a focus on some recent developments
2017
Jean-François Coeurjolly, Adeline Leclercq-Samson Eds.; International audience; This article presents different recent theoretical results illustrating the interactions between probability and algorithmics. These contributions deal with various topics: cellular automata and calculability, variable length Markov chains and persistent random walks, perfect sampling via coupling from the past. All of them involve discrete dynamics on complex random structures.; Cet article présente différents résultats récents de nature théorique illustrant les interactions entre probabilités et algorithmique. Ces contributions traitent de sujets variés : automates cellulaires et calculabilité, chaînes de Mark…
Approche préventive de la qualité des données d'importation dans le contexte de la protéomique clinique
2011
International audience; Dans le domaine biomédical, la protéomique est confrontée à des sources de données de plus en plus nombreuses et à des volumes de données très importants du fait de la multiplication des technologies dites à haut débit. L'hétérogénéité de la provenance des données implique de fait une hétérogénéité dans la représentation et le contenu de ces données. Les données peuvent aussi se révéler incorrectes ce qui engendre des erreurs sur les conclusions des expériences protéomiques. Notre approche a pour objectif de garantir la qualité initiale des données lors de leur importation dans un système d'information dédié à la protéomique. Elle est basée sur le couplage entre des …