Effects of dynamic response time in an evolving market

Considering the time scales of global information and personal reaction, we study the role of dynamic response time in the evolution of collective behavior in an evolving market. The insensitiveness to the market information makes the population cluster around a kind of extreme behavior, in which they always follow what happened last time, while a sensitive population tends to self-segregate into opposing groups. The average success rate R among all the agents is found to have a nonmonotonic dependence on the time scale parameter q. There exists a critical value below (above) which R decreases (increases) with the rise of q. Theoretical analyses demonstrate that the higher efficiency found in the market with an insensitive population is related to its predictability. In such a predictable market, the agents following current prediction have a higher winning probability than those rejecting it. Analytical calculations are in good agreement with numerical data.     

Failsafe modes in incomplete minority game

We make a failsafe extension to the incomplete minority game model, give a brief analysis on how incompleteness will effect system efficiency. Simulations that limited incompleteness in strategies can improve the system efficiency. Among three failsafe modes, the “Back-to-Best” mode brings most significant improvement and keeps the system efficiency in a long range of incompleteness. A simple analytic formula has a trend which matches simulation results. The IMMG model is used to study the effect of distribution, and we find that there is one junction point in each series of curves, at which system efficiency is not influenced by the distribution of incompleteness. When the concentration of incompleteness weakens the effect. On the other side of , concentration will be helpful. When p_I is close to zero agents using incomplete strategies have on average better profits than those using standard strategies, and the “Back-to-Best” agents have a wider range of p_I to win.     

Prisoner's Dilemma Game on Clustered Scale-Free Networks under Different Initial Distributions

The evolutionary prisoner＇s dilemma game is investigated under different initial distributions for cooperators and defectors on scale-free networks with a tunable clustering coefficient. It is found that, on the one hand, cooperation can be enhanced with the increasing clustering coefficient when only the most connected nodes are occupied by cooperators initially. On the other hand, if cooperators just occupy the lowest-degree nodes at the beginning, then the higher the value of the clustering coefficient, the more unfavorable the environment for cooperators to survive for the increment of temptation to defect. Thereafter, we analytically argue these nontrivial phenomena by calculating the cooperation probability of the nodes with different degrees in the steady state, and obtain the critical values of initial frequency of cooperators below which cooperators would vanish finally for the two initial distributions.     

Thermally activated dewetting of organic thin films: the case of pentacene on SiO<Subscript>2</Subscript> and gold

The morphology of pentacene organic thin films deposited on SiO₂ and Au(111) surfaces using organic molecular beam deposition (OMBD) has been characterized by a multi-technique approach. Among the techniques applied were X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and thermal desorption spectroscopy (TDS). Our rather detailed studies reveal that on both substrates the growth is strongly influenced by dewetting and islanding phenomena, yielding very rough surfaces. Surprisingly, substantial changes in the morphology were observed also after deposition on room-temperature samples on a time scale of several hours. The rather extensive set of in situ XPS data was analyzed in the framework of a simple model, which allows us to derive rather detailed information on the roughness parameters.     

Prisoner's Dilemma on Co-Evolving Networks without Strategy Update

We investigate the game theory in a structured population with the assumption that the evolution of network structure is far faster than that of strategy update. We find that the degree distribution for the finM network consists of two distinct parts： the low degree part which is contributed to by defectors and a broadband in the regime with high degree which is formed by cooperators. The structure of the final network and the final strategy pattern have also been numerically proved to be independent of the game parameters.     

Illusory versus genuine control in agent-based games

In the Minority, Majority and Dollar Games (MG, MAJG, $G) agents compete for rewards, acting in accord with the previously best-performing of their strategies. Different aspects/kinds of real-world markets are modelled by these games. In the MG, agents compete for scarce resources; in the MAJG agents imitate the group to exploit a trend; in the $G agents attempt to predict and benefit both from trends and changes in the direction of a market. It has been previously shown that in the MG for a reasonable number of preliminary time steps preceding equilibrium (Time Horizon MG, THMG), agents’ attempt to optimize their gains by active strategy selection is “illusory”: the hypothetical gains of their strategies is greater on average than agents’ actual average gains. Furthermore, if a small proportion of agents deliberately choose and act in accord with their seemingly worst performing strategy, these outperform all other agents on average, and even attain mean positive gain, otherwise rare for agents in the MG. This latter phenomenon raises the question as to how well the optimization procedure works in the THMAJG and TH$G. We demonstrate that the illusion of control is absent in THMAJG and TH$G. This provides further clarification of the kinds of situations subject to genuine control, and those not, in set-ups a priori defined to emphasize the importance of optimization.     

Separated cross-sections in \pi^{0}_{} electroproduction at threshold at Q2 = 0.05GeV2/c2

The differential cross-sections σ₀ = σ_T + εσ_L , σ_LT , and σ_TT of electroproduction from the proton were measured from threshold up to an additional center-of-mass energy of 40MeV, at a value of the photon four-momentum transfer of Q ² = 0.05 GeV²/c² and a center-of-mass angle of θ = 90^° . By an additional out-of-plane measurement with polarized electrons σ_LT' was determined. This showed for the first time the presence of an imaginary part of the s -wave above the threshold, which is usually interpreted as a unitary cusp. The predictions of the Heavy Baryon Chiral Perturbation Theory (HBChPT) are in disagreement with these data. On the other hand, the data are somewhat better predicted by the MAID phenomenological model and are in good agreement with the dynamical model DMT.     

A method of experimentally probing transverse momentum dependent distributions

We calculate the double spin asymmetry A_LL$A_{LL}$ for the π⁰${\pi }^0$ production in semi-inclusive deep inelastic lepton–proton scattering with a spectator model of power-law and a model based on the factorization ansatz. We also calculate the double spin asymmetry for the integration over parts of the kinematic range for the setups of the experiments of COMPASS, HERMES, and JLab. We find that the results are characteristically dependent on the model used. Therefore, we suggest that the measurements of the double spin asymmetry provides a method of experimentally probing the transverse momentum dependent distributions.     

Dimensionality-induced effects on transport properties of poly(G)-poly(C)

We consider a ladder model of DNA for addressing the relation between the transport properties and electronic structure and the interbase coupling in poly(G)-poly(C). Based on the negative eigenvalue theorem and transfer matrix method, the density of states and current-voltage characteristics are evaluated, and an expression for the dependence of the band gap on intra- and inter-strand nucleobase couplings is proposed. There exists a semiconducting-metallic transition in poly(G)-poly(C) by modulating the interbase coupling, and the physical nature is traced back to dimensionality-induced effects. Our results provide possibility for interpreting a variety of transport behaviors observed in DNA molecules.