Search results for "Fluctuations"

Resonant activation in polymer translocation: new insights into the escape dynamics of molecules driven by an oscillating field

2010

The translocation of molecules across cellular membranes or through synthetic nanopores is strongly affected by thermal fluctuations. In this work we study how the dynamics of a polymer in a noisy environment changes when the translocation process is driven by an oscillating electric field. An improved version of the Rouse model for a flexible polymer has been adopted to mimic the molecular dynamics, by taking into account the harmonic interactions between adjacent monomers and the excluded-volume effect by introducing a Lennard–Jones potential between all beads. A bending recoil torque has also been included in our model. The polymer dynamics is simulated in a two-dimensional domain by num…

Translocation time of periodically forced polymer chains.

2010

6 páginas, 11 figuras.-- PACS number(s): 36.20.-r, 05.40.-a, 87.15.A-, 87.10.-e

Synchronization and fluctuations for interacting stochastic systems with individual and collective reinforcement

2020

The Pólya urn is the paradigmatic example of a reinforced stochastic process. It leads to a random (non degenerated) time-limit. The Friedman urn is a natural generalization whose a.s. time-limit is not random anymore. In this work, in the stream of previous recent works, we introduce a new family of (finite) systems of reinforced stochastic processes, interacting through an additional collective reinforcement of mean field type. The two reinforcement rules strengths (one componentwise, one collective) are tuned through (possibly) different rates n −γ. In the case the reinforcement rates are like n −1 , these reinforcements are of Pólya or Friedman type as in urn contexts and may thus lead …

CENTRAL LIMIT THEOREM FOR KERNEL ESTIMATOR OF INVARIANT DENSITY IN BIFURCATING MARKOV CHAINS MODELS

2021

Bifurcating Markov chains (BMC) are Markov chains indexed by a full binary tree representing the evolution of a trait along a population where each individual has two children. Motivated by the functional estimation of the density of the invariant probability measure which appears as the asymptotic distribution of the trait, we prove the consistence and the Gaussian fluctuations for a kernel estimator of this density based on late generations. In this setting, it is interesting to note that the distinction of the three regimes on the ergodic rate identified in a previous work (for fluctuations of average over large generations) disappears. This result is a first step to go beyond the thresh…

CENTRAL LIMIT THEOREM FOR BIFURCATING MARKOV CHAINS

2020

Bifurcating Markov chains (BMC) are Markov chains indexed by a full binary tree representing the evolution of a trait along a population where each individual has two children. We first provide a central limit theorem for general additive functionals of BMC, and prove the existence of three regimes. This corresponds to a competition between the reproducing rate (each individual has two children) and the ergodicity rate for the evolution of the trait. This is in contrast with the work of Guyon (2007), where the considered additive functionals are sums of martingale increments, and only one regime appears. Our first result can be seen as a discrete time version, but with general trait evoluti…

Counterion-mediated attraction and kinks on loops of semiflexible polyelectrolyte bundles.

2006

The formation of kinks in a loop of bundled polyelectrolyte filaments is analyzed in terms of the thermal fluctuations of charge density due to polyvalent counterions adsorbed on the polyelectrolyte filaments. It is found that the counterion-mediated attraction energy of filaments depends on their bending. By consideration of curvature elasticity energy and counterion-mediated attraction between polyelectrolyte filaments, the characteristic width of the kink and the number of kinks per loop is found to be in reasonable agreement with existing experimental data for rings of bundled actin filaments.

Elliptic flow of identified hadrons in Pb-Pb collisions at √sNN = 2.76 TeV

2015

The elliptic flow coefficient (v2) of identified particles in Pb-Pb collisions at √ sNN = 2.76 TeV was measured with the ALICE detector at the Large Hadron Collider (LHC). The results were obtained with the Scalar Product method, a two-particle correlation technique, using a pseudo-rapidity gap of |∆η| > 0.9 between the identified hadron under study and the reference particles. The v2 is reported for π ±, K±, K0 S , p+p, φ, Λ+Λ, Ξ −+Ξ + and Ω−+Ω + in several collision centralities. In the low transverse momentum (pT) region, pT 3 GeV/c. peerReviewed

Anisotropic flow and flow fluctuations of identified hadrons in Pb–Pb collisions at √sNN = 5.02 TeV

2023

Valūtas un valūtas kursa svārstību ierobežošana ilgtermiņa līgumos

2017

Bakalaura darbs „Valūta un valūtas kursa svārstību ierobežošana ilgtermiņa līgumos” sniedz ieskatu jautājumos par maksājuma izdarīšanas valūtu un valūtas kursa svārstību ierobežošanu līgumā. Darba mērķis ir izpētīt, kādā valūtā maksājums izdarāms, ja puses līgumā par to tieši nav vienojušās, kā arī noskaidrot efektīvākos valūtas kursa svārstību ierobežošanas veidus. Pētījuma rezultātā autore konstatē kritērijus, atbilstoši kuriem tiek noteikta maksājuma izdarīšanas valūta un identificē efektīvākos mehānismus valūtas kursa svārstību ierobežošanai līguma ietveros. Atslēgvārdi: valūta, valūtas kurss, valūtas kursa svārstības, darījuma risks, valūtas de-valvācija, valūtas revalvācija.

The Origin of Non-thermal Fluctuations in Multiphase Flow in Porous Media

2021

Core flooding experiments to determine multiphase flow in properties of rock such as relative permeability can show significant fluctuations in terms of pressure, saturation, and electrical conductivity. That is typically not considered in the Darcy scale interpretation but treated as noise. However, in recent years, flow regimes that exhibit spatio-temporal variations in pore scale occupancy related to fluid phase pressure changes have been identified. They are associated with topological changes in the fluid configurations caused by pore-scale instabilities such as snap-off. The common understanding of Darcy-scale flow regimes is that pore-scale phenomena and their signature should have a…