570 research outputs found
Gene length as a regulator for ribosome recruitment and protein synthesis : theoretical insights
The authors would like to acknowledge the funding provided by the European Union Seventh Framework Programme [FP7/2007–2013] (NICHE; grant agreement 289384) (LDF). LDF also acknowledges the funding provided by the São Paulo Research Foundation (FAPESP - grant #2015/26989-4). AM was partially funded by the UK Biotechnology and Biological Research Council (BBSRC), through grant BB/N015711/1. LC would like to acknowledge Maria Carmen Romano, Jean Hausser, Marco Cosentino Lagomarsino, Jean-Charles Walter and Norbert Kern for early discussions on this work, and the CNRS for having granted him a “demi-délégation” (2017–18). We would like to dedicate this work in memory of Maxime Clusel and Vladimir Lorman.Peer reviewedPublisher PDFPublisher PD
Fractal escapes in Newtonian and relativistic multipole gravitational fields
We study the planar motion of test particles in gravitational fields produced
by an external material halo, of the type found in many astrophysical systems,
such as elliptical galaxies and globular clusters. Both the Newtonian and the
general-relativistic dynamics are examined, and in the relativistic case the
dynamics of both massive and massless particles are investigated. The halo
field is given in general by a multipole expansion; we restrict ourselves to
multipole fields of pure order, whose Newtonian potentials are homogeneous
polynomials in cartesian coordinates. A pure (n)-pole field has (n) different
escapes, one of which is chosen by the particle according to its initial
conditions. We find that the escape has a fractal dependency on the initial
conditions for (n>2) both in the Newtonian and the relativistic cases for
massive test particles, but with important differences between them. The
relativistic motion of massless particles, however, was found to be regular for
all the fields we could study. The box-counting dimension was used in each case
to quantify the sensitivity to initial conditions which arises from the
fractality of the escape route.Comment: 17 pages, 7 figures, uses REVTE
Cooperative response and clustering : Consequences of membrane-mediated interactions among mechanosensitive channels
Peer reviewedPublisher PD
Escape from attracting sets in randomly perturbed systems
The dynamics of escape from an attractive state due to random perturbations
is of central interest to many areas in science. Previous studies of escape in
chaotic systems have rather focused on the case of unbounded noise, usually
assumed to have Gaussian distribution. In this paper, we address the problem of
escape induced by bounded noise. We show that the dynamics of escape from an
attractor's basin is equivalent to that of a closed system with an
appropriately chosen "hole". Using this equivalence, we show that there is a
minimum noise amplitude above which escape takes place, and we derive
analytical expressions for the scaling of the escape rate with noise amplitude
near the escape transition. We verify our analytical predictions through
numerical simulations of a two-dimensional map with noise.Comment: up to date with published versio
Cato in Libya (Lucan 9)
Após a derrota e o assassinato de Pompeu, Catão tenta reorganizar as forças republicanas no Norte da África. Sua luta é política e filosófica. Lucano apresenta esse desafio através dos discursos de Catão e seus interlocutores, bem como através de uma fantástica travessia do deserto líbio. Este trabalho procura mostrar como a forma da narrativa expõe os dilemas das personagens e do próprio narrador diante da crise representada por esse momento. Estudaremos sobretudo a ordenação dos conteúdos, as intervenções do narrador, o emprego das falas em discurso direto e a manipulação da geografia africana.After Pompey’s defeat at Pharsalus and his assassination in Egypt, Cato tries to reorganise the republican forces in North Africa. His fight is a political and philosophical one. Lucan presents this challenge by means of a fantastic crossing of the Libyan desert as well as through speeches by Cato and his interlocutors. This paper attempts to show how the shape of the narrative exposes the dilemmas faced by the characters and the narrator himself in this context of crisis. I shall address the order of the contents in book 9, the narrator’s interventions, the use of direct speech and the manipulation of African geography
Signatures of fractal clustering of aerosols advected under gravity
Aerosols under chaotic advection often approach a strange attractor. They
move chaotically on this fractal set but, in the presence of gravity, they have
a net vertical motion downwards. In practical situations, observational data
may be available only at a given level, for example at the ground level. We
uncover two fractal signatures of chaotic advection of aerosols under the
action of gravity. Each one enables the computation of the fractal dimension
of the strange attractor governing the advection dynamics from data
obtained solely at a given level. We illustrate our theoretical findings with a
numerical experiment and discuss their possible relevance to meteorology.Comment: Accepted for publication in Phys. Rev. E (Rapid Communications
Integrated stress response of Escherichia coli to methylglyoxal : transcriptional readthrough from the nemRA operon enhances protection through increased expression of glyoxalase I
© 2013 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.Peer reviewedPublisher PD
Collective response of self-organized clusters of mechanosensitive channels
Peer reviewedPublisher PD
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