共查询到20条相似文献,搜索用时 31 毫秒
1.
P. Dommersnes S. Straumsnes E.G. Flekkøy T. Nicolai S. Roux 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(4):669-677
We study the hydrodynamic properties of polymers and more generally self-similar structures using a new recursion model. The
hydrodynamic interaction between monomers is modeled by the standard Green's function of Stokes flow in which an ultrametric
distance is substituted for the usual Euclidean distance. This leads to a model where the long-range hydrodynamic interactions
and the long-range correlations of the polymer conformation can both be accounted for and yet allow for analytical solutions.
We explore the asymptotic as well as the finite size corrections to the scaling behavior with this model. In order to compare
the results of the present scheme with more conventional techniques a generalized version of the existing mean field results
by Kirkwood and Riseman for the hydrodynamic drag is introduced.
Received 26 August 1998 and Received in final form 7 December 1998 相似文献
2.
A. A. Buchachenko G. Chałasiński M. M. Szczęśniak 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(1):147-153
The results of high-level ab initio calculations are reported for
the interatomic potentials describing YbHe, Yb2, TmHe and TmYb van der
Waals interactions. It is found that the interaction properties of Tm and
Yb are very similar and the interaction anisotropy in the TmHe and TmYb
complexes is very small. We analyze the long-range behavior of the isotropic
and anisotropic interaction potentials and discuss some implications for cold
and ultracold atomic collisions of the lanthanide atoms. 相似文献
3.
Y. Jia G. Yu J. Dong 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):433-439
The binding energies and sizes of excitons, and energy splitting of
the bright-dark excitons in single-walled carbon nanotubes have been
calculated using the nonorthogonal tight-binding model, supplemented
by the long-range Coulomb interaction. It is found that the binding
energies and the sizes of excitons not only depend on tube's
diameter d, but also its chirality. However, the splitting of the
bright-dark excitons mostly depends on 1/d2. Our obtained
results show that the curvature effect is very important for the
exciton excitations in the SWNTs, especially in the smaller diameter
ones. 相似文献
4.
R. Beuc H. Skenderovi T. Ban D. Vea G. Pichler W. Meyer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):209-214
We measured a very distinct satellite band at 875.2 nm between two resonance lines of cesium. Spectral simulation using Spies
and Meyer [#!ref1!#] ab initio potential curves and an appropriate transition dipole moment function was compared with experimental profile. Implications
of the investigated satellite band at 875.2 nm in the field of ultracold cesium atom collisions are discussed with a special
emphasize to new possibilities of the photoassociation of two ground state atoms leading to the formation of ultracold intermediate
long-range molecules.
Received 07 March 2001 and Received in final form 14 May 2001 相似文献
5.
LINMin CHENTian-Lun 《理论物理通讯》2004,42(3):373-378
We introduce the Olami-Feder-Christensen (OFC) model on a square lattice with some “rewired“ longrange connections having the properties of small world networks. We find that our model displays the power-law behavior, and connectivity topologies are very important to model‘s avalanche dynamical behaviors. Our model has some behaviors different from the OFC model on a small world network with “added“ long-range connections in our previous work [LIN Min, ZHAO Xiao-Wei, and CHEN Tian-Lun, Commun. Theor. Phys. (Beijing, China) 41 (2004) 557.]. 相似文献
6.
J. Barré F. Bouchet T. Dauxois S. Ruffo 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):577-591
We study an analytically tractable model with long-range interactions for which an out-of-equilibrium very long-lived coherent structure spontaneously appears. The dynamics of this model is indeed
very peculiar: a bicluster forms at low energy and is stable for very long time, contrary to statistical mechanics predictions. We first explain the
onset of the structure, by approximating the short time dynamics with a forced Burgers equation. The emergence of the bicluster
is the signature of the shock waves present in the associated hydrodynamical equations. The striking quantitative agreement
with the dynamics of the particles fully confirms this procedure. We then show that a very fast timescale can be singled out
from a slower motion. This enables us to use an adiabatic approximation to derive an effective Hamiltonian that describes
very well the long time dynamics. We then get an explanation of the very long time stability of the bicluster: this out-of-equilibrium
state corresponds to a statistical equilibrium of an effective mean-field dynamics.
Received 28 February 2002 / Received in final form 24 July 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: Thierry.Dauxois@ens-lyon.fr
RID="b"
ID="b"UMR-CNRS 5672
RID="c"
ID="c"UMR 5582 相似文献
7.
Epidemic outbreaks in complex heterogeneous networks 总被引:23,自引:0,他引:23
Y. Moreno R. Pastor-Satorras A. Vespignani 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(4):521-529
We present a detailed analytical and numerical study for the spreading of infections with acquired immunity in complex population
networks. We show that the large connectivity fluctuations usually found in these networks strengthen considerably the incidence
of epidemic outbreaks. Scale-free networks, which are characterized by diverging connectivity fluctuations in the limit of
a very large number of nodes, exhibit the lack of an epidemic threshold and always show a finite fraction of infected individuals.
This particular weakness, observed also in models without immunity, defines a new epidemiological framework characterized
by a highly heterogeneous response of the system to the introduction of infected individuals with different connectivity.
The understanding of epidemics in complex networks might deliver new insights in the spread of information and diseases in
biological and technological networks that often appear to be characterized by complex heterogeneous architectures.
Received 20 September 2001 and Received in final form 4 February 2002 相似文献
8.
Lyotropic bicontinuous cubic phase single crystals investigated using high-resolved X-ray scattering
Single crystals of an Ia
d bicontinuous direct cubic phase formed by a non-ionic surfactant in water are investigated using high-resolved X-ray diffraction.
The shape of the Bragg peaks confirms the existence of a 3D long-range order inside the cubic phase. A weak diffuse scattered
intensity signal is measured very near the Bragg peaks. We attribute this signal to thermal diffuse scattering (TDS) and we
give an estimation of the contribution of elastic waves to this TDS.
Received 4 May 2000 相似文献
9.
By using the measure of concurrence, the entanglement of the ground state in the one-dimensional Anderson model is studied with consideration of the long-range correlations. Three kinds of correlations are discussed. We compare the effects of the long-rang Gaussian and power-law correlations between the site energies on the concurrence, and demonstrate the existence of the band structure of the concurrence in the power-law case. The emergence of the sharp kink on the concurrence curve shown in the intraband or in the interband indicates the position at which the localization extent of the state may have the severe variation. We use the Rudin-Shapiro model to describe the site energy distribution of the nucleotides of the DNA chain: guanine (G), adenine (A), cytosine(C), thymine (T). This model is a tetradic quasiperiodic sequence and is shown to be long-range correlated. Our results show that correlations between the site energies increase the concurrences. 相似文献
10.
Epidemics in small world networks 总被引:1,自引:0,他引:1
M.M. Telo da Gama A. Nunes 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):205-208
For many infectious diseases, a small-world network on an underlying regular
lattice is a suitable simplified model for the contact structure of the host
population. It is well known that the contact network, described in this
setting by a single parameter, the small-world parameter p, plays an
important role both in the short term and in the long term dynamics of
epidemic spread.
We have studied the effect of the network structure on models of immune
for life diseases and found that in addition to the reduction of the
effective transmission rate, through the screening of infectives, spatial
correlations may strongly enhance the stochastic fluctuations. As a
consequence, time series of unforced Susceptible-Exposed-Infected-Recovered
(SEIR) models provide patterns of recurrent epidemics with realistic
amplitudes, suggesting that these models together with complex networks of
contacts are the key ingredients to describe the prevaccination dynamical
patterns of diseases such as measles and pertussis.
We have also studied the role of the host contact strucuture in
pathogen antigenic variation, through its effect on the
final outcome of an invasion by a viral strain of a population where a
very similar virus is endemic. Similar viral strains are modelled
by the same infection and reinfection parameters, and by a given degree of
cross immunity that represents the antigenic distance between the
competing strains. We have found, somewhat surprisingly, that clustering
on the network decreases the potential to sustain pathogen diversity. 相似文献
11.
Within the Hubbard-Holstein model with long-range Coulomb forces, we revisit the charge-ordering (CO) scenario for the superconducting cuprates and account for the presence or the absence of a formed stripe phase in different classes of cuprates. We also evaluate the mean-field and the fluctuation-corrected critical lines for CO and we relate them with the various pseudogap crossover lines occurring in the cuprates and we discuss a mechanism for their peculiar isotopic dependence. Considering the dynamical nature of the CO transition, we explain the spread of T∗ and of its isotopic shift, obtained with experimental probes with different characteristic time scales. 相似文献
12.
We discuss the long-range nature of the molecules produced in recent experiments on molecular Bose-Einstein condensation. The properties of these molecules depend on the full two-body Hamiltonian and not just on the states of the system in the absence of interchannel couplings. The very long-range nature of the state is crucial to the efficiency of production in the experiments. Our many-body treatment of the gas accounts for the full binary physics and describes properly how these molecular condensates can be directly probed. 相似文献
13.
H. Hinrichsen M. Howard 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(4):635-643
We introduce a model for the spreading of epidemics by long-range infections and investigate the critical behaviour at the
spreading transition. The model generalizes directed bond percolation and is characterized by a probability distribution for
long-range infections which decays in d spatial dimensions as . Extensive numerical simulations are performed in order to determine the density exponent and the correlation length exponents and for various values of . We observe that these exponents vary continuously with , in agreement with recent field-theoretic predictions. We also study a model for pairwise annihilation of particles with
algebraically distributed long-range interactions.
Received: 4 September 1998 / Accepted: 22 September 1998 相似文献
14.
Yundong Zhang Wei Qiu Jianbo Ye Nan Wang Jinfang Wang He Tian Hao Wang Ping Yuan 《Physics letters. A》2008,372(15):2724-2729
We show that coherent population oscillations effect produces a very narrow spectral hole in the absorption spectrum. The large dispersion of the refractive index associated with this hole permits us to achieve a group velocity as low as 1496.25 m/s at room temperature in an erbium-doped fiber. When the input intensity is equal to the saturation intensity, the dispersion is optimal. The optimal dispersion corresponds to the maximum fractional delay. Therefore, the input intensity can be used as a control parameter to increase the fractional delay. Our theoretical results based on population oscillation agree very well with the experimental data. In addition, we confirm that the spectral hole experiences power broadening for optical fibers of different lengths. 相似文献
15.
Modelling fluctuations of financial time series: from cascade process to stochastic volatility model 总被引:4,自引:0,他引:4
J.F. Muzy J. Delour E. Bacry 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(3):537-548
In this paper, we provide a simple, “generic” interpretation of multifractal scaling laws and multiplicative cascade process
paradigms in terms of volatility correlations. We show that in this context 1/f power spectra, as recently observed in reference [23], naturally emerge. We then propose a simple solvable “stochastic volatility”
model for return fluctuations. This model is able to reproduce most of recent empirical findings concerning financial time
series: no correlation between price variations, long-range volatility correlations and multifractal statistics. Moreover,
its extension to a multivariate context, in order to model portfolio behavior, is very natural. Comparisons to real data and
other models proposed elsewhere are provided.
Received 22 May 2000 相似文献
16.
17.
The bid–ask spread is taken as an important measure of the financial market liquidity. In this article, we study the dynamics of the spread return and the spread volatility of four liquid stocks in the Chinese stock market, including the memory effect and the multifractal nature. By investigating the autocorrelation function and the Detrended Fluctuation Analysis (DFA), we find that the spread return is the lack of long-range memory, while the spread volatility is long-range time correlated. Besides, the spread volatilities of different stocks present long-range cross-correlations. Moreover, by applying the Multifractal Detrended Fluctuation Analysis (MF-DFA), the spread return is observed to possess a strong multifractality, which is similar to the dynamics of a variety of financial quantities. Different from the spread return, the spread volatility exhibits a weak multifractal nature. 相似文献
18.
We study the effect of dielectric inhomogeneities on the interaction between two planparallel charged surfaces with oppositely
charged mobile charges in between. The dielectric constant between the surfaces is assumed to be different from the dielectric
constant of the two semiinfinite regions bounded by the surfaces, giving rise to electrostatic image interactions. We show
that on the weak-coupling level the image charge effects are generally small, making their mark only in the second-order fluctuation
term. However, in the strong-coupling limit, the image effects are large and fundamental. They modify the interactions between
the two surfaces in an essential way. Our calculations are particularly useful in the regime of parameters where computer
simulations would be difficult and extremely time consuming due to the complicated nature of the long-range image potentials. 相似文献
19.
We use a recently improved version of the chiral nucleon-nucleon potential at next-to-next-to-leading order to calculate the 1S0 pairing gap in isospin-symmetric nuclear matter. The pairing potential consists of the long-range one- and two-pion exchange terms and two short-distance NN-contact couplings. We find that the inclusion of the two-pion exchange at next-to-next-to-leading order reduces substantially the cutoff dependence of the 1S0 pairing gap determined by solving a regularised BCS equation. Our results are close to those obtained with the universal low-momentum nucleon-nucleon potential Vlow-k or the phenomenological Gogny D1S force. 相似文献
20.
B. Podobnik D. F. Fu H. E. Stanley P. Ch. Ivanov 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):47-52
We develop a stochastic process with two coupled variables where
the absolute values of each variable exhibit long-range power-law
autocorrelations and are also long-range cross-correlated. We investigate how
the scaling exponents characterizing power-law autocorrelation and long-range
cross-correlation behavior in the absolute values of the generated variables
depend on the two parameters in our model. In particular, if the
autocorrelation is stronger, the cross-correlation is also stronger. We test
the utility of our approach by comparing the autocorrelation and
cross-correlation properties of the time series generated by our model with
data on daily returns over ten years for two major financial indices, the
Dow Jones and the S&P500, and on daily returns of two well-known
company stocks, IBM and Microsoft, over five years. 相似文献