Effects of Contrarians in the Minority Game

We study the effects of the presence of contrarians in an agent-based model of competing populations. Contrarians are common in societies. These contrarians are agents who deliberately prefer to hold an opinion that is contrary to the prevailing idea of the commons or normal agents. Contrarians are introduced within the context of the Minority Game (MG), which is a binary model for an evolving and adaptive population of agents competing for a limited resource. Results of numerical simulations reveal that the average success rate among the agents depends non-monotonically on the fraction $a_{c}$ of contrarians. For small $a_{c}$, the contrarians systematically outperform the normal agents by avoiding the crowd effect and enhance the overall success rate. For high $a_{c}$, the anti-persistent nature of the MG is disturbed and the few normal agents outperform the contrarians. Qualitative discussion and analytic results for the small $a_{c}$ and high $a_{c}$ regimes are also presented, and the crossover behavior between the two regimes is discussed.Comment: revtex, 11 pages, 4 figure

Dynamics of opinion formation in a small-world network

The dynamical process of opinion formation within a model using a local majority opinion updating rule is studied numerically in networks with the small-world geometrical property. The network is one in which shortcuts are added to randomly chosen pairs of nodes in an underlying regular lattice. The presence of a small number of shortcuts is found to shorten the time to reach a consensus significantly. The effects of having shortcuts in a lattice of fixed spatial dimension are shown to be analogous to that of increasing the spatial dimension in regular lattices. The shortening of the consensus time is shown to be related to the shortening of the mean shortest path as shortcuts are added. Results can also be translated into that of the dynamics of a spin system in a small-world network.Comment: 10 pages, 5 figure

Effectiveness of erythropoietin supplementation against chronic heart failure with anemia, and its effect on serum hypersensitive C reaction protein, homocysteic acid and Btype natriuretic peptide

Purpose: To study the effectiveness of exogenous erythropoietin (EPO) against chronic heart failure (CHF) with anemia, and its effect on serum hypersensitive C reaction protein (hs-CRP), homocysteic acid (Hcy ) and B-type natriuretic peptide (BNP).Methods: A total of 136 patients suffering from CHF with anemia from June 2015 to June 2017 were randomly divided into observation group (n = 68) and control group (n = 68). On the basis of conventional anti-heart failure therapy, the control group received oral ferrous sulfate tablets, while the observation group received oral ferrous sulfate tablets combined with EPO subcutaneous injection. Blood indices, cardiac function and serology were determined and tested in all patients before treatment, and at 4 months after treatment.Results: After treatment, hemoglobin (Hb), hematocrit (HCT), red blood cell (RBC), blood platelet count (PLT) and serum iron were significantly higher than those before treatment in the two groups; the levels in the observation group were significantly higher than those in control group (p <0.05). Following treatment, left ventricular ejection fraction (LVEF), and 6-minute walking distance in the observation group were significantly higher than those in the control group, while end-diastolic dimension (LVEDD), end-systolic dimension (LVESD) and cardiac functional grading in the observation group were significantly lower than those in the control group (p < 0.05). After treatment, hs-CRP, Hcy and BNP were significantly lower than pre-treatment values in the two groups, while the values for the observation group were significantly lower than those of control group (p <0.05). Correlation analysis showed that LVEF and Hb were negatively correlated with hs-CRP, Hcy and BNP (p <0.05).Conclusion: Serum hs-CRP, Hcy and BNP are involved in the occurrence and progression of CHF with anemia. Exogenous EPO can effectively improve anemia and cardiac function in these patients.Keywords: Erythropoietin, Chronic heart failure, Anemia, C-reaction protein, B-type natriuretic peptid