Suchergebnisse

We're all familiar with the concept of duels. They can be deadly, such as those fought between two suitors vying for a lady's affections or sheriffs and outlaws battling it out in the American Old West, or they can end in both parties enjoying a beer, with the loser buying a round after an intense game of darts. A duel is simply a game with two players, each having a probability of winning that game and each having an intrinsic marksmanship, or ability, associated with his or her performance. Of course, the worst player--the one with the worst marksmanship--might have an advantage such as extra bullets or extra points, but in a normal unbiased situation, common sense tells us that the higher the marksmanship, the higher the probability of winning the duel. The mathematical treatment of this game confirms our simple expectations. If more than two players participate, a series of duels might be needed to determine the absolute winner. This is the case in sports tournaments, which pair teams in all possible ways until the ultimate winner emerges. A truel is a generalization of a duel involving three players and slightly different rules. ; We acknowledge financial support from the Spanish government and Fondo Europeo de Desarrollo Regional (FEDER EU) through projects FIS2004-5073 and FIS2004-953. Pau Amengual is supported by a grant from the government of the Balearic Islands. ; Peer reviewed

We consider a model for the evolution of surname distribution under a gender-equality measure currently being discussed by the Spanish Parliament (whereby children would adopt their mother's and father's surnames in alphabetical order). We quantify how this would bias the alphabetical distribution of surnames, and analyze its effect on the present distribution of surnames in Spain. ; The authors acknowledge financial support by the MICINN (Spain) and FEDER (EU) through project FIS2007-60327. L.F.L. is supported by the JAEPredoc program of CSIC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript ; Peer reviewed

5 pages, 6 figures. ; This letter focus on the effect of repulsive interactions on the adoption of an external message in an opinion model. With a simple change in the rules, we modify the Deffuant \emph{et al.} model to incorporate the presence of repulsive interactions. We will show that information receptiveness is optimal for an intermediate fraction of repulsive links. Using the master equation as well as Monte Carlo simulations of the message-free model, we identify the point where the system becomes optimally permeable to external influence with an order-disorder transition. ; We acknowledge financial support by the MEC (Spain) and FEDER (EU) through project FIS2007-60327. TVM acknowledges the support of FCT (Portugal) through Grant No. SFRH/BD/23709/2005, MP is supported by the Belgian Federal Government (IAP project "NOSY: Nonlinear systems, stochastic processes and statistical mechanics"). ; Peer reviewed

9 pages.-- PACS numbers: 05.45.-a, 87.19.La, 05.40.Ca, 87.10.+e.-- Final full-text version of the paper available at: http://dx.doi.org/10.1103/PhysRevE.74.046220. ; We study the control of oscillations in a system of inhibitory coupled noisy excitable and oscillatory units. Using dynamical properties of inhibition, we find regimes when the oscillations can be suppressed but the information signal of a certain frequency can be transmitted through the system. The mechanism of this phenomenon is a resonant interplay of noise and the transmission signal provided by certain value of inhibitory coupling. Analyzing a system of three or four oscillators representing neural clusters, we show that this suppression can be effectively controlled by coupling and noise amplitudes. ; A.Z. acknowledges financial support from Volkswagen- Stiftung (Germany). We acknowledge financial support from the Spanish Government and FEDER (EU) through projects FIS2004-5073, FIS2004-953, and the EU NoE BioSim (LSHB-CT-2004-005137).

9 pages.-- PACS numbers: 02.70.Rr, 64.60.Cn, 75.10.Hk, 05.10.Ln.-- Final full-text version of the paper available at: http://dx.doi.org/10.1103/PhysRevE.74.046702. ; We propose a recursive procedure to estimate the microcanonical density of states in multicanonical Monte Carlo simulations which relies only on measurements of moments of the energy distribution, avoiding entirely the need for energy histograms. This method yields directly a piecewise analytical approximation to the microcanonical inverse temperature beta(E) and allows improved control over the statistics and efficiency of the simulations. We demonstrate its utility in connection with recently proposed schemes for improving the efficiency of multicanonical sampling, either with adjustment of the asymptotic energy distribution or with the replacement of single spin flip dynamics with collective updates. ; This work was supported by FCT (Portugal) and the European Union, through POCTI (QCA III). Two of the authors, J.V.L. and M.D.C., were supported by FCT Grant Nos. SFRH/BD/1261/2000 and SFRH/BD/ 7003/2001, respectively. R.T. was supported by the Spanish Government and FEDER (EU) through Project Nos. FIS2004-5073, FIS2004-953.

8 pages, 7 figures.-- PACS nrs.: 05.50.+q, 64.60.Cn, 05.70.Jk.-- ArXiv pre-print available: http://lanl.arxiv.org/abs/cond-mat/0402138 ; We present an exact solution of a one-dimensional Ising chain with both nearest-neighbor and random long-range interactions. Not surprisingly, the solution confirms the mean-field character of the transition. This solution also predicts the finite-size scaling that we observe in numerical simulations. ; This work was financed by FCT (Portugal) and the European Union, through POCTI (QCA III). One of the authors (J.V.L.) was supported by FCT grant (Portugal) No. SFRH/BD/1261/2000 and another author (R.T.) by MCYT (Spain) and FEDER through project Nos. BFM2000-1108 and BFM2001-0341-C02-01. ; Peer reviewed