2,916 research outputs found
Models of protein production along the cell cycle: an investigation of possible sources of noise
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
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
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)
https://digitalmaine.com/alien_docs/4124/thumbnail.jp
Calculs 3d prédictifs pour la conception d'alvéoles de stockage de déchets radioactifs HAVL
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)
Personal-JS
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 â Personal Jesus by Depeche Mode â together. The user creates or joins a âjamâ 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
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