Search results for "model."

Dynamics of a FitzHugh-Nagumo system driven by a periodic signal in the presence of colored noise

2007

We analyze the dynamics of a FitzHugh-Naguno system, driven by a periodic signal, in the presence of coloured noise. We consider the effects of the fluctuations by inserting in the deterministic FitzHugh-Nagumo model a term of additive Gaussian noise. We study the system in two different cases: the fluctuations affect the dynamics of the membrane potential (CASE I), the recovery variable is subjected to noise (CASE II). We review briefly the effects of the white noise, responsible for the appearance of resonant activation (RA) and noise enhanced stability (NES) phenomena. Afterwards we study the two cases in the presence of a coloured noise with correlation time tau. We investigate the effe…

Inference of proto-neutron star properties from gravitational-wave data in core-collapse supernovae

2021

The eventual detection of gravitational waves from core-collapse supernovae (CCSN) will help improve our current understanding of the explosion mechanism of massive stars. The stochastic nature of the late post-bounce gravitational wave signal due to the non-linear dynamics of the matter involved and the large number of degrees of freedom of the phenomenon make the source parameter inference problem very challenging. In this paper we take a step towards that goal and present a parameter estimation approach which is based on the gravitational waves associated with oscillations of proto-neutron stars (PNS). Numerical simulations of CCSN have shown that buoyancy-driven g-modes are responsible …

Studies of transition-edge sensor physics : thermal models and noise

2011

This thesis focuses on studying the noise in transition-edge sensors (TES). More specifically, the aim is to find an explanation for the observed excess noise that is limiting their performance and has been troubling the TES field in recent years. Several theories have been put forth but a definitive answer is still missing. In the early stages of this thesis work a novel theory was presented for the noise in a special TES geometry. In our theory the excess noise is caused by correlated fluctuations of superconductivity at the phase boundary between normal and superconducting states. Data from more recent experiments does not give solid support for the theory and in this thesis the validity…

Functional Interaction between the Nucleosome Remodeling Factor ISWI and the Hsrω non-coding RNA

2009

Functional Interaction between the Nucleosome Remodeling Factor ISWI and the Hsr-omega non-coding RNA

2009

Functional Interaction between the Nucleosome Remodeling Factor ISWI and the Hsrω non-coding RNA

2009

Quantum Non-Markovian Piecewise Dynamics from Collision Models

2017

Recently, a large class of quantum non-Markovian piecewise dynamics for an open quantum system obeying closed evolution equations has been introduced [B. Vacchini, Phys. Rev. Lett. 117, 230401 (2016)]. These dynamics have been defined in terms of a waiting-time distribution between quantum jumps, along with quantum maps describing the effect of jumps and the system's evolution between them. Here, we present a quantum collision model with memory, whose reduced dynamics in the continuous-time limit reproduces the above class of non-Markovian piecewise dynamics, thus providing an explicit microscopic realization.

The Nucleosome Remodeling Factor ISWI Functionally Interacts with the Hsr-ω non-coding RNA

2009

Magnetic quantum criticality in quasi-one-dimensional Heisenberg antiferromagnet Cu(C4H4N2)(NO3)2

2016

We analyze exciting recent measurements [Phys. Rev. Lett. 114 (2015) 037202] of the magnetization, differential susceptibility and specific heat on one dimensional Heisenberg antiferromagnet Cu(C4H4N2)(NO3)2 (CuPzN) subjected to strong magnetic fields. Using the mapping between magnons (bosons) in CuPzN and fermions, we demonstrate that magnetic field tunes the insulator towards quantum critical point related to so-called fermion condensation quantum phase transition (FCQPT) at which the resulting fermion effective mass diverges kinematically. We show that the FCQPT concept permits to reveal the scaling behavior of thermodynamic characteristics, describe the experimental results quantitativ…

Non-linear analysis of plane steel prestressed truss in fire

2002

The concept of analysis of 2-D static loaded prestressed steel trusses till failure during fire using a modified method of forces is presented. Failure of steel trusses in fire is based on the criterion of stresses. Behaviour of steel is described by non-linear constitutive model (based on hypo-elastic Ramberg-Osgood formula and Dorn creep theory) and Plem proposition (for string). Both models are approximated in calculations by hyperbolic Norton-Bailey rule. Fire simulates thermal force as an action of high temperature that increases linearly up to some level. The complete formulation of this method is illustrated by the algorithm of model parameters identification. Analysis of results for…