Search results for "HB"
showing 10 items of 1066 documents
Finite-Size Scaling Study of the Simple Cubic Three-State Potts Glass
1991
During the last few years the Potts glass model has attracted more and more attention. It is considered as a first step towards modelling the phase transition of structural and orientational glasses. A mean-field approach /1/ predicts a low temperature behavior completely different from what is known from Ising spin glasses /2/. But short range models differ markedly from mean-field-predictions. So it is natural to ask, how the short range Potts glass behaves. Especially the question of the lower critical dimension d l is important, below which a finite temperature transition ceases to occur. We tried to answer this by combining Monte-Carlo simulations with a finite-size scaling analysis. T…
Multiparticle breathers for a chain with double-quadratic on-site potential
1999
We investigate the existence and properties of multiparticle breathers for a one-dimensional model with harmonic nearest neighbor interactions where a group of r particles $(r=1,2,3,\dots{})$ perform interwell oscillations between both wells of a double-quadratic on-site potiential. We find two types of such breathers. For the first type the breather frequency $\ensuremath{\Omega}$ is within the single-particle oscillator spectrum, and the ``residence'' time of each breather particle in the left and right well is about the same. For the second breather $\ensuremath{\Omega}$ is below that spectrum, and the ratio ${\ensuremath{\tau}}_{L}/{\ensuremath{\tau}}_{R}$ of the residence time in the l…
The coupling of the X1Σ+and a3Σ+states of the atom pair Na + Cs and modelling cold collisions
2006
The states X1?+ and a3?+ correlated to the ground-state asymptote of Na (3s) and Cs (6s) atoms have been experimentally investigated using high resolution Fourier-transform spectroscopy. The hyperfine splitting of the a3?+ state levels is partially resolved. Transitions to asymptotic vibrational levels of the a3?+ and X1?+ states were recorded simultaneously. The joint evaluation of the data of both the a3?+ and the X1?+ states allows us to determine accurate potential energy curves of both electronic states. Coupled-channels calculations are finally applied for deriving long range dispersion parameters and the exchange contribution of the molecular potentials, yielding a reliable descripti…
A global descriptor of spatial pattern interaction in the galaxy distribution
1997
We present the function J as a morphological descriptor for point patterns formed by the distribution of galaxies in the Universe. This function was recently introduced in the field of spatial statistics, and is based on the nearest neighbor distribution and the void probability function. The J descriptor allows to distinguish clustered (i.e. correlated) from ``regular'' (i.e. anti-correlated) point distributions. We outline the theoretical foundations of the method, perform tests with a Matern cluster process as an idealised model of galaxy clustering, and apply the descriptor to galaxies and loose groups in the Perseus-Pisces Survey. A comparison with mock-samples extracted from a mixed d…
Clustering statistics in cosmology
2002
The main tools in cosmology for comparing theoretical models with the observations of the galaxy distribution are statistical. We will review the applications of spatial statistics to the description of the large-scale structure of the universe. Special topics discussed in this talk will be: description of the galaxy samples, selection effects and biases, correlation functions, Fourier analysis, nearest neighbor statistics, Minkowski functionals and structure statistics. Special attention will be devoted to scaling laws and the use of the lacunarity measures in the description of the cosmic texture.
Slowing down in the three-dimensional three-state Potts glass with nearest neighbor exchange : A Monte Carlo study
1998
,Static and dynamic properties of the Potts model on the simple cubic lattice with nearest neighbor ±Ĵ-interaction are obtained from Monte Carlo simulations in a temperature range where full thermal equilibrium still can be achieved (T/Ĵ ≥ 0.6). For a lattice size L = 16, in this range finite size effects are still negligible, but the data for the spin glass susceptibility agree with previous extrapolations based on finite size scaling of very small lattices. While the static properties are compatible with a zero temperature transition, they certainly do not prove it. Unlike the Ising spin glass, the decay of the time-dependent order parameter is compatible with a simple Kohlrausch function…
On the Path and Area J<sub>x1</sub>-Integral Components and their Relationship to the Out-of-Plane Constraint in Elastic Cracked Plates
2009
In this paper, the path and area components of the Jx1-integral, JP and JA, in three dimensional elastic cracked plates under mode-I loading are investigated aiming at relating them to the out-of-plane constraint conditions resulting from different specimen thicknesses. It is concluded that the JP and JA components of the Jx1-integral vary in the region where the out-of-plane constraint extends. Sufficiently far from the crack front, these integrals tend to stabilize, indicating that the thickness constraint vanishes and that a 2D-like stress and strain fields have been reached. A pure plane strain condition is only attained when the specimen thickness is very large when compared to the in-…
Statistics of Galaxy Clustering
2006
In this introductory talk we will establish connections between the statistical analysis of galaxy clustering in cosmology and recent work in mainstream spatial statistics. The lecture will review the methods of spatial statistics used by both sets of scholars, having in mind the cross-fertilizing purpose of the meeting series. Special topics will be: description of the galaxy samples, selection effects and biases, correlation functions, nearest neighbor distances, void probability functions, Fourier analysis, and structure statistics.
SEA presidential address: Group connectivity and cooperation
2011
A model-free methodology is used for the first time to estimate a daily volatility index (VIBEX-NEW) for the Spanish financial market.We use a public data set of daily option prices to compute this index and showthat daily changes in VIBEXNEW display a negative, tight contemporaneous relationship with IBEX daily returns, contrary to other common volatility indicators, as an implied volatility indicator or a GARCH(1,1) conditional volatility model. This relationship is approximately symmetric to the sign on VIBEX-NEW changes and asymmetric to the IBEX-35 returns sign, which make it clearly a suitable volatility index for the Spanish stock market. We also examine the relationship between curr…
Interdisciplinarité et interculturalité à partir de deux romans : Les Nuits de Strasbourg d’Assia Djebar et Le Village de l’Allemand ou le journal de…
2021
My presentation focuses on interdisciplinarity and interculturality on the basis of two novels, "Les Nuits de Strasbourg" by Assia Djebar and "Le Village de l'Allemand ou le journal des frères Schiller" by Boualem Sansal. Firstly, I reflect in a general way on interdisciplinarity and its affinity with interculturality before addressing these issues in my corpus and in my work. Secondly, I look at some theories, interdisciplinary and sometimes intercultural, that help me to study my corpus in a harmonious way, which I illustrate with concrete analyses referring to the thought of Édouard Glissant. Finally, I propose interdisciplinary developments of an intercultural approach, that of Michael …