scholarly journals Computational Biophysical Modeling of the Radiation Bystander Effect in Irradiated Cells

Radiation ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 33-51
Author(s):  
Paweł Wysocki ◽  
Krzysztof W. Fornalski
Keyword(s):  
Monte Carlo ◽  
Probability Distribution ◽  
Ionizing Radiation ◽  
Monte Carlo Methods ◽  
Bystander Effect ◽  
Direct Interaction ◽  
Point Of View ◽  
Biophysical Modeling ◽  
New Approach ◽  
Probability Tree

It is well known that ionizing radiation can cause damages to cells that interact with it directly. However, many studies have shown that damages also occur in cells that have not experienced direct interaction. This is due to the so-called bystander effect, which is observed when the irradiated cell sends signals that can damage neighboring cells. Due to the complexity of this effect, it is not easy to strictly describe it biophysically, and thus it is also difficult to simulate. This article reviews various approaches to modeling and simulating the bystander effect from the point of view of radiation biophysics. In particular, the last model presented within this article is part of a larger project of modeling the response of a group of cells to ionizing radiation using Monte Carlo methods. The new approach presented here is based on the probability tree, the Poisson distribution of signals and the saturated dose-related probability distribution of the bystander effect’s appearance, which makes the model very broad and universal.

scholarly journals Comparison of Direct and Adjoint k and α-Eigenfunctions

2021 ◽  
Vol 2 (2) ◽  
pp. 132-151
Author(s):  
Vito Vitali ◽  
Florent Chevallier ◽  
Alexis Jinaphanh ◽  
Andrea Zoia ◽  
Patrick Blaise
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Methods ◽  
Energy Transport ◽  
Distinct Point ◽  
Point Of View ◽  
Critical Systems ◽  
Small Deviations ◽  
Power Iteration ◽  
Continuous Energy ◽  
Fission Probability

Modal expansions based on k-eigenvalues and α-eigenvalues are commonly used in order to investigate the reactor behaviour, each with a distinct point of view: the former is related to fission generations, whereas the latter is related to time. Well-known Monte Carlo methods exist to compute the direct k or α fundamental eigenmodes, based on variants of the power iteration. The possibility of computing adjoint eigenfunctions in continuous-energy transport has been recently implemented and tested in the development version of TRIPOLI-4®, using a modified version of the Iterated Fission Probability (IFP) method for the adjoint α calculation. In this work we present a preliminary comparison of direct and adjoint k and α eigenmodes by Monte Carlo methods, for small deviations from criticality. When the reactor is exactly critical, i.e., for k0 = 1 or equivalently α0 = 0, the fundamental modes of both eigenfunction bases coincide, as expected on physical grounds. However, for non-critical systems the fundamental k and α eigenmodes show significant discrepancies.

On solving stochastic differential equations

2019 ◽  
Vol 25 (2) ◽  
pp. 155-161
Author(s):  
Sergej M. Ermakov ◽  
Anna A. Pogosian
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Markov Chain Monte Carlo ◽  
Differential Equations ◽  
Stochastic Differential Equations ◽  
Integral Equations ◽  
Wide Class ◽  
Monte Carlo Methods ◽  
New Approach ◽  
Difference Approximations

Abstract This paper proposes a new approach to solving Ito stochastic differential equations. It is based on the well-known Monte Carlo methods for solving integral equations (Neumann–Ulam scheme, Markov chain Monte Carlo). The estimates of the solution for a wide class of equations do not have a bias, which distinguishes them from estimates based on difference approximations (Euler, Milstein methods, etc.).

scholarly journals Monte-Carlo methods for the pricing of American options: a semilinear BSDE point of view

2019 ◽  
Vol 65 ◽  
pp. 294-308x ◽  
Author(s):  
Bruno Bouchard ◽  
Ki Wai Chau ◽  
Arij Manai ◽  
Ahmed Sid-Ali
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Methods ◽  
Numerical Experiments ◽  
Branching Processes ◽  
Type Equation ◽  
Reaction Diffusion ◽  
Payoff Function ◽  
Point Of View ◽  
Option Prices ◽  
Diffusion Type

We extend the viscosity solution characterization proved in [5] for call/put American option prices to the case of a general payoff function in a multi-dimensional setting: the price satisfies a semilinear reaction/diffusion type equation. Based on this, we propose two new numerical schemes inspired by the branching processes based algorithm of [8]. Our numerical experiments show that approximating the discontinuous driver of the associated reaction/diffusion PDE by local polynomials is not efficient, while a simple randomization procedure provides very good results.

ON THE NON-TRIVIALITY OF THE λφ4 MODEL

2009 ◽  
Vol 24 (18n19) ◽  
pp. 3605-3611
Author(s):  
L. KUPPAN ◽  
V.H. LIEW ◽  
S.K. FOONG
Keyword(s):  
Monte Carlo ◽  
Correlation Function ◽  
Symmetry Breaking ◽  
Monte Carlo Methods ◽  
Functional Integral ◽  
Coupling Constant ◽  
New Approach ◽  
Dimensional Spacetime ◽  
Unpublished Note ◽  
Open Question

The λφ4 model is conventionally used to explain the origin of mass of elementary particles through the Spontaneous Symmetry Breaking (SSB) phenomena. The triviality status of the λφ4 model in 4-dimensional spacetime remains an open question despite attempts by several authors. This study establishes a new approach to determine the triviality status of the λφ4 model based on an unpublished note by Professor Bryce DeWitt. We adopted the DeWitt's Ansatz for the 2-point connected correlation function on the lattice [Formula: see text] where α is a parameter that measures the departure from triviality. Calling α's continuum counterpart as β, then a non-zero value of β signifies non-triviality of the λφ4 model. The 2-point connected correlation function, given in terms of an Euclidean functional integral, is computed numerically via Monte Carlo methods. Our analysis, based on β, is different from the traditional analysis based on the renormalized coupling constant λR. To test the new approach, we performed the simulation in 2 dimensions and obtained results that are consistent with previous findings: 2-dimensional λφ4 model is non-trivial. Finally, for the case in 4 dimensions, our results show that the model is non-trivial.

MODELING OF A TURBULENT ETHYLENE/AIR JET FLAME USING HYBRID FINITE VOLUME/MONTE CARLO METHODS

2009 ◽  
Vol 1 (1) ◽  
pp. 37-53 ◽  
Author(s):  
Ranjan S. Mehta ◽  
Anquan Wang ◽  
Michael F. Modest ◽  
Daniel C. Haworth
Keyword(s):  
Monte Carlo ◽  
Finite Volume ◽  
Monte Carlo Methods ◽  
Jet Flame ◽  
Air Jet
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