2,826 research outputs found

    Models of protein production along the cell cycle: an investigation of possible sources of noise

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    In this article, we quantitatively study, through stochastic models, the efects of several intracellular phenomena, such as cell volume growth, cell division, gene replication as well as fuctuations of available RNA polymerases and ribosomes. These phenomena are indeed rarely considered in classic models of protein production and no relative quantitative comparison among them has been performed. The parameters for a large and representative class of proteins are determined using experimental measures. The main important and surprising conclusion of our study is to show that despite the signifcant fuctuations of free RNA polymerases and free ribosomes, they bring little variability to protein production contrary to what has been previously proposed in the literature. After verifying the robustness of this quite counter-intuitive result, we discuss its possible origin from a theoretical view, and interpret it as the result of a mean-feld efect

    A Stochastic Analysis of Autoregulation of Gene Expression

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    This paper analyzes, in the context of a prokaryotic cell, the stochastic variability of the number of proteins when there is a control of gene expression by an autoregulation scheme. The goal of this work is to estimate the efficiency of the regulation to limit the fluctuations of the number of copies of a given protein. The autoregulation considered in this paper relies mainly on a negative feedback: the proteins are repressors of their own gene expression. The efficiency of a production process without feedback control is compared to a production process with an autoregulation of the gene expression assuming that both of them produce the same average number of proteins. The main characteristic used for the comparison is the standard deviation of the number of proteins at equilibrium. With a Markovian representation and a simple model of repression, we prove that, under a scaling regime, the repression mechanism follows a Hill repression scheme with an hyperbolic control. An explicit asymptotic expression of the variance of the number of proteins under this regulation mechanism is obtained. Simulations are used to study other aspects of autoregulation such as the rate of convergence to equilibrium of the production process and the case where the control of the production process of proteins is achieved via the inhibition of mRNAs

    Dynamics of latent voters

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    We study the effect of latency on binary-choice opinion formation models. Latency is introduced into the models as an additional dynamic rule: after a voter changes its opinion, it enters a waiting period of stochastic length where no further changes take place. We first focus on the voter model and show that as a result of introducing latency, the average magnetization is not conserved, and the system is driven toward zero magnetization, independently of initial conditions. The model is studied analytically in the mean-field case and by simulations in one dimension. We also address the behavior of the Majority Rule model with added latency, and show that the competition between imitation and latency leads to a rich phenomenology

    Alien Registration- Renaud, Vincent W. (Belfast, Waldo County)

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    Calculs 3d prédictifs pour la conception d'alvéoles de stockage de déchets radioactifs HAVL

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    National audienceFor the "HA cells" experimentation in the URL of Bure (Andra), coupled mechanical modelings (creep or hydraulic behavior) were carried out to predict the expected behavior of argillites during excavation of a disposal cell (stresses, displacements, EDZ). These predictions are then compared to in situ measurements (displacement and pore pressure).Dans le cadre de l'expérimentation "alvéoles HA" au laboratoire souterrain de recherche de Bure (Andra), des modélisations mécaniques couplées (comportement différé ou hydraulique) ont été réalisées pour prédire le comportement attendu des argilites à l'excavation d'une alvéole (contraintes, déplacements, EDZ). Elles sont ensuite comparées avec les mesures in situ (déplacements et pression interstitielle)


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    Presented at the 2nd Web Audio Conference (WAC), April 4-6, 2016, Atlanta, Georgia.Personal-JS is a web application based on the Web Audio API and Web RTC standards where connected users play synchronously loops of a well-known song – Personal Jesus by Depeche Mode – together. The user creates or joins a “jam” room, and then can play some audio loops with other users. The application is based on Sync library (http://github.com/collective-soundworks/sync) to synchronize the different devices through the PeerJS WebRTC wrapper (http://peerjs.com) and thus requires no web server, except for serving the audio loops