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Ramulu H.G.,CNRS Laboratory of Analysis, Topology, Probabilities
Frontiers in cellular and infection microbiology | Year: 2012

The increase in huge number of genomic sequences in recent years has contributed to various genetic events such as horizontal gene transfer (HGT), gene duplication and hybridization of species. Among them HGT has played an important role in the genome evolution and was believed to occur only in Bacterial and Archaeal genomes. As a result, genomes were found to be chimeric and the evolution of life was represented in different forms such as forests, networks and species evolution was described more like a rhizome, rather than a tree. However, in the last few years, HGT has also been evidenced in other group such as metazoa (for example in root-knot nematodes, bdelloid rotifers and mammals). In addition to HGT, other genetic events such as transfer by retrotransposons and hybridization between more closely related lineages are also well established. Therefore, in the light of such genetic events, whether the evolution of metazoa exists in the form of a tree, network or rhizome is highly questionable and needs to be determined. In the current review, we will focus on the role of HGT, retrotransposons and hybridization in the metazoan evolution. Source

Bardos C.,University Paris Diderot | Nouri A.,CNRS Laboratory of Analysis, Topology, Probabilities
Journal of Mathematical Physics | Year: 2012

Well-posedness of the Cauchy problem is analyzed for a singular Vlasov equation governing the evolution of the ionic distribution function of a quasineutral fusion plasma. The Penrose criterium is adapted to the linearized problem around a time and space homogeneous distribution function showing (due to the singularity) more drastic differences between stable and unstable situations. This pathology appears on the full nonlinear problem, well-posed locally in time with analytic initial data, but generally ill-posed in the Hadamard sense. Eventually with a very different class of solutions, mono-kinetic, which constrains the structure of the density distribution, the problem becomes locally in time well-posed. © 2012 American Institute of Physics. Source

Boutellis A.,Aix - Marseille University | Abi-Rached L.,CNRS Laboratory of Analysis, Topology, Probabilities | Raoult D.,Aix - Marseille University
Infection, Genetics and Evolution | Year: 2014

Two genera of lice parasitize humans: Pthirus and Pediculus. The latter is of significant public health importance and comprises two ecotypes: the body louse and the head louse. These ecotypes are morphologically and genetically notably similar; the body louse is responsible for three infectious diseases: Louse-borne epidemic typhus, relapsing fever, and trench fever. Mitochondrial DNA studies have shown that there are three obviously divergent clades of head lice (A, B and C), and only one clade of body lice is shared with head lice (clade A). Each clade has a unique geographic distribution. Lice have been parasitizing humans for millions of years and likely dispersed throughout the World with the human migrations out of Africa, so they can be good markers for studying human evolution. Here, we present an overview of the origin of human lice and their role in vector pathogenic bacteria that caused epidemics, and we review the association between lice clades and human migrations. © 2014 Elsevier B.V. Source

Le Rousseau J.,CNRS Laboratory of Analysis, Topology, Probabilities | Le Rousseau J.,CNRS Physics Laboratory | Robbiano L.,University of Versailles
Archive for Rational Mechanics and Analysis | Year: 2010

In a bounded domain of Rn+1, n ≧ 2, we consider a second-order elliptic operator, A = ∂2x0 - ∇x · (c(x)∇x), where the (scalar) coefficient c(x) is piecewise smooth yet discontinuous across a smooth interface S. We prove a local Carleman estimate for A in the neighborhood of any point of the interface. The "observation" region can be chosen independently of the sign of the jump of the coefficient c at the considered point. The derivation of this estimate relies on the separation of the problem into three microlocal regions and the Calderón projector technique. Following the method of Lebeau and Robbiano (Comm Partial Differ Equ 20:335-356, 1995) we then prove the null controllability for the linear parabolic initial problem with Dirichlet boundary conditions associated with the operator ∂t - ∇x · (c(x)∇x. © Springer-Verlag 2009. Source

Bufetov A.I.,CNRS Laboratory of Analysis, Topology, Probabilities | Bufetov A.I.,National Research University Higher School of Economics | Solomyak B.,University of Washington
Communications in Mathematical Physics | Year: 2013

We study deviation of ergodic averages for dynamical systems given by self-similar tilings on the plane and in higher dimensions. The main object of our paper is a special family of finitely-additive measures for our systems. An asymptotic formula is given for ergodic integrals in terms of these finitely-additive measures, and, as a corollary, limit theorems are obtained for dynamical systems given by self-similar tilings. © 2012 Springer-Verlag Berlin Heidelberg. Source

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