Search results for "Monte carlo method"
showing 10 items of 1234 documents
Pattern Formation Kinetics for Charged Molecules on Surfaces: Microscopic Correlation Function Analysis
2011
The kinetics of pattern formation and phase separation in a system of two types of oppositely charged molecules with competing short- and long-range interactions on surfaces/interfaces is studied combining three methods: a microscopic formalism of the joint correlation functions, reverse Monte Carlo, and nonequilibrium charge-screening factors. The molecular ordering occurs on the background of the Ostwald ripening and thus is strongly nonequilibrium. We have demonstrated how initial random distribution of molecules is changed for loose similar-molecule aggregates, with further reorganization into dense macroscopic domains of oppositely charged molecules. Pattern formation process is charac…
Searches for B0 decays to combinations of charmless isoscalar mesons
2004
We search for B meson decays into two-body combinations of eta, eta', omega, and phi mesons from 89 million B B-bar pairs collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find the branching fraction BF(B0 -> eta omega) = (4.0^{+1.3}_{-1.2} +- 0.4) x 10^-6 with a significance of 4.3 sigma. For all the other decay modes we set the following 90% confidence level upper limits on the branching fractions, in units of 10^-6 : BF(B0 -> eta eta)<2.8, BF(B0 -> eta eta')<4.6, BF(B0 -> eta' eta')<10, BF(B0 -> eta'omega)<2.8, BF(B0 -> eta phi)<1.0, BF(B0 -> eta' phi)<4.5, BF(B0 -> phi phi)<1.5.
Microscopic calculations of the hipernucleus λ5He
1993
Ground state results for the hypernucleus λ5He are reported. They have been calculated with a variatonal Jastrow-like trial wave function and also within the Diffusion Monte Carlo method. Simple central potential have been used to describe NN and λN interactions. The validity of the rigid core approximation is discussed. Guardiola Barcena, Rafael, Rafael.Guardiola@ific.uv.es Navarro Salas, Jose, Jose.Navarro@ific.uv.es
Unusual finite size effects in the Monte Carlo simulation of microphase formation of block copolymer melts
1995
Extensive Monte Carlo simulations are presented for the Fried-Binder model of block copolymer melts, where polymer chains are represented as self and mutually avoiding walks on a simple cubic lattice, and monomer units of different kind (A, B) repel each other if they are nearest neighbors (e AB > O). Choosing a chain length N = 20, vacancy concentration Φ v = 0,2, composition f = 3/4, and a L × L × L geometry with periodic boundary conditions and 8 ≤ L ≤ 32, finite size effects on the collective structure factor S(q) and the gyration radii are investigated. It is shown that already above the microphase separation transition, namely when the correlation length ζ(T) of concentration fluctuat…
Monte Carlo simulation in phylogenies: an application to test the constancy of evolutionary rates.
1994
Monte Carlo simulation has commonly been used in phylogenetic studies to test different tree-reconstruction methods, and consequently, its application for testing evolutionary models can be considered as a natural extension of this usage. Repetitive simulation of a given evolutionary process, under the restrictions imposed by the model to be tested, along a determinate tree topology allow the estimate of probability distributions for the desired parameters. Next, the phylogenetic tree can be reconstructed again without the constraints of the model, and the parameter of interest, derived from this tree, can be compared to the corresponding probability distribution derived from the restricted…
Membrane fluidity and the surface properties of the lipid bilayer: ESR experiment and computer simulation
2009
Penetration of the liposome membranes formed in the gel phase from DPPC (DPPC liposomes) and in the liquid-crystalline phase from egg yolk lecithin (EYL liposomes) by the TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) and 16 DOXYL (2-ethyl-2-(15-methoxy-oxopentadecyl)-4,4-dimethyl-3-oxazolidinyloxy) spin probes has been investigated. The penetration process was followed by 120 hours at 24(0)C, using the electron spin resonance (ESR) method. The investigation of the kinetics of the TEMPO probe building into the membranes of both types of liposomes revealed differences appearing 30 minutes after the start of the experiment. The number of TEMPO particles built into the EYL liposome membranes beg…
Early Treatment in HCV: Is it a Cost-Utility Option from the Italian Perspective?
2016
In Italy, the Italian Pharmaceutical Agency (AIFA) criteria used F3–F4 fibrosis stages as the threshold to prioritise the treatment with interferon (IFN)-free regimens, while in genotype 1 chronic hepatitis C (G1 CHC) patients with fibrosis of liver stage 2, an approach with pegylated interferon (PEG-IFN)-based triple therapy with simeprevir was suggested. The key clinical question is whether, in an era of financial constraints, the application of a universal IFN-free strategy in naive G1 CHC patients is feasible within a short time horizon. The aim of this study is to perform an economic analysis to estimate the cost-utility of the early innovative therapy in Italy for managing hepatitis C…
Guide to Practical Work with the Monte Carlo Method
2002
The guide is structured such that we proceed from the “easy” simulation methods and algorithms to the more sophisticated. For each method the algorithms are presented by the technique of stepwise refinement. We first present the idea and the basic outline. From then on we proceed by breaking up the larger logical and algorithmic structures into smaller ones, until we have reached the level of single basic statements. Sometimes we may elect not to go to such a depth and the reader is asked to fill in the gaps.
A panel cointegration approach to the estimation of the peseta real exchange rate
2001
Abstract In this paper we estimate different specifications of a model for the determination of the bilateral real exchange rate of the peseta relative to nine European Union members. The model is based on Meese and Rogoff (The Journal of Finance 43 (1988) 933) monetary approach as extended by MacDonald (Journal of International Financial Markets, Institutions and Money 8 (1998) 117). The applied econometric techniques are the recent panel cointegration tests developed by Kao (Journal of Econometrics 90 (1999) 1), McCoskey and Kao (A Monte Carlo comparison of tests for cointegration in panel data. Journal of Propagations in Probability and Statistics 1 (2001) 165) and Pedroni (Oxford Bullet…
Suppression of capillary wave broadening of interfaces in binary alloys due to elastic interactions.
2005
By Monte Carlo simulations in the constant-temperature--constant-pressure ensemble a planar interface between unmixed A-rich and B-rich phases of a binary (A, B) alloy on a compressible diamond lattice is studied. No significant capillary wave broadening of the concentration profile across the interface is observed, unlike lattice models of incompressible mixtures and fluids. The distortion of the lattice structure across the interface is studied.