Heat-Bath and Metropolis Dynamics in Ising-like Models on Directed Regular Random Graphs.

Using a single-site mean-field approximation (MFA) and Monte Carlo simulations, we examine Ising-like models on directed regular random graphs. The models are directed-network implementations of the Ising model, Ising model with absorbing states, and majority voter models. When these nonequilibrium models are driven by the heat-bath dynamics, their stationary characteristics, such as magnetization, are correctly reproduced by MFA as confirmed by Monte Carlo simulations.

Ising Model: Recent Developments and Exotic Applications.

Solving in his PhD thesis the one-dimensional version of a certain lattice model of ferromagnetism formulated by his supervisor Lenz [...

Fluctuation relations in a nonequilibrium system: Surface tension and effective temperature in an Ising-doped voter model.

Fluctuation relations of Jarzynski and Crooks enable efficient calculations of a free-energy difference between equilibrium states. In the present paper, we provide some numerical evidence that these relations can also be used for a two-dimensional Ising-doped voter model, which is a nonequilibrium system with a violated detailed balance. Adopting the method of Híjar and Sutmann, we implement a protocol that switches between periodic and antiperiodic boundary conditions and induces formation of an interface in the model.

Equilibrium behavior in a nonequilibrium system: Ising-doped voter model on complete graph.

While the Ising model belongs to the realm of equilibrium statistical mechanics, the voter model is an example of a nonequilibrium system. We examine an opinion formation model, which is a mixture of Ising and voter agents with concentrations p and 1-p, respectively. Although in our model for p<1 a detailed balance is violated, on a complete graph the average magnetization in the stationary state for any p>0 is shown to satisfy the same equation as for the pure Ising model (p=1).

Stability and Evolution of Synonyms and Homonyms in Signaling Game.

Synonyms and homonyms appear in all natural languages. We analyze their evolution within the framework of the signaling game. Agents in our model use reinforcement learning, where probabilities of selection of a communicated word or of its interpretation depend on weights equal to the number of accumulated successful communications.

Endovascular coil embolization of the left internal carotid artery aneurysm - case report.

In the current case report we present a novel case of a successful coil embolization of the left internal carotid artery aneurysm. The patient presented with neck pain and a palpable pulsating tumor and was admitted to the vascular surgery clinic where an angio-CT scan of the neck was performed. Angio-CT revealed a left internal carotid artery aneurysm with a narrow neck.

Evolution towards Linguistic Coherence in Naming Game With Migrating Agents.

As an integral part of our culture and way of life, language is intricately related to the migrations of people. To understand whether and how migration shapes language formation processes, we examine the dynamics of the naming game with migrating agents. (i) When all agents may migrate, the dynamics generates effective surface tension that drives the coarsening.

Impact of Preoperative Aspirin on Long-Term Outcomes in Diabetic Patients Following Coronary Artery Bypass Grafting: a Propensity Score Matched Study.

Introduction: This study aimed to determine the effect of preoperative aspirin administration on early and long-term clinical outcomes in patients suffering from diabetes mellitus (DM) undergoing coronary artery bypass grafting (CABG).

Methods: In this observational study, a total of 315 patients were included and grouped according to the time interval between their last aspirin dose and the time of surgery; patients who had been continued aspirin intake with last administered dose ≤ 24-hours before CABG (n=144) and those who had been given the last dose of aspirin between 24 to 48 hours before CABG (n=171).

Results: Multivariable analysis showed that the continuation of preoperative aspirin intake ≤ 24 hours before CABG in patients with DM is associated with reduced incidence of 30-day major adverse cardiac and cerebral events (MACCE) (P=0.

Cluster Structure of Optimal Solutions in Bipartitioning of Small Worlds.

Using simulated annealing, we examine a bipartitioning of small worlds obtained by adding a fraction of randomly chosen links to a one-dimensional chain or a square lattice. Models defined on small worlds typically exhibit a mean-field behavior, regardless of the underlying lattice. Our work demonstrates that the bipartitioning of small worlds does depend on the underlying lattice.

Entropic long-range ordering in an adsorption-desorption model.

We examine a two-dimensional nonequilibrium lattice model where particles adsorb at empty sites and desorb when the number of neighboring particles is greater than a given threshold. In a certain range of parameters the model exhibits entropic ordering similar to some hard-core systems. However, contrary to hard-core systems, on increasing the density of particles the ordering is destroyed.

Emergence of linguistic conventions in multi-agent reinforcement learning.

Recently, emergence of signaling conventions, among which language is a prime example, draws a considerable interdisciplinary interest ranging from game theory, to robotics to evolutionary linguistics. Such a wide spectrum of research is based on much different assumptions and methodologies, but complexity of the problem precludes formulation of a unifying and commonly accepted explanation. We examine formation of signaling conventions in a framework of a multi-agent reinforcement learning model.

Prevalence of Antibodies to Aujeszky's Disease Virus in Wild Boar in Poland, Between 2011 and 2014: A Retrospective Study.

Introduction: Aujeszky's disease virus (ADV) infects a wide range of animals, including members of the family, . domestic and wild pigs, as well as wild boar. Since wild boar are a potential ADV reservoir and a source of infection for domestic pigs, the aim of the study was to evaluate ADV antibody prevalence in the Polish wild boar population, during the years 2011 to 2014.

Phase transition and power-law coarsening in an Ising-doped voter model.

We examine an opinion formation model, which is a mixture of Voter and Ising agents. Numerical simulations show that even a very small fraction (∼1%) of the Ising agents drastically changes the behavior of the Voter model. The Voter agents act as a medium, which correlates sparsely dispersed Ising agents, and the resulting ferromagnetic ordering persists up to a certain temperature.

Language competition in a population of migrating agents.

Influencing various aspects of human activity, migration is associated also with language formation. To examine the mutual interaction of these processes, we study a Naming Game with migrating agents. The dynamics of the model leads to formation of low-mobility clusters, which turns out to break the symmetry of the model: although the Naming Game remains symmetric, low-mobility languages are favored.

Phase transitions in Ising models on directed networks.

We examine Ising models with heat-bath dynamics on directed networks. Our simulations show that Ising models on directed triangular and simple cubic lattices undergo a phase transition that most likely belongs to the Ising universality class. On the directed square lattice the model remains paramagnetic at any positive temperature as already reported in some previous studies.

Robust criticality of an Ising model on rewired directed networks.

We show that preferential rewiring, which is supposed to mimic the behavior of financial agents, changes a directed-network Ising ferromagnet with a single critical point into a model with robust critical behavior. For the nonrewired random graph version, due to a constant number of out-links for each site, we write a simple mean-field-like equation describing the behavior of magnetization; we argue that it is exact and support the claim with extensive Monte Carlo simulations. For the rewired version, this equation is obeyed only at low temperatures.

Immune response in pigs treated with therapeutic doses of enrofloxacin at the time of vaccination against Aujeszky's disease.

The effect of treatment with enrofloxacin was studied on the postvaccinal immune response in pigs. Forty pigs were used (control not vaccinated (C), control vaccinated (CV), vaccinated, received enrofloxacin (ENRO)). From day -1 to day 3 pigs from ENRO group received enrofloxacin at the recommended dose.

Emergence of social structures via preferential selection.

We examine a weighted-network multiagent model with preferential selection such that agents choose partners with probability p(w), where w is the number of their past selections. When p(w) increases sublinearly with the number of past selections [p(w)∼w(α),α<1], agents develop a uniform preference for all other agents. At α=1, this state loses stability and more complex structures form.

Generic criticality of community structure in random graphs.

We examine a community structure in random graphs of size n and link probability p/n determined with the Newman greedy optimization of modularity. Calculations show that for p<1 communities are nearly identical with clusters. For p=1 the average sizes of a community s(av) and of the giant community s(g) show a power-law increase s(av)∼n(α') and s(g)∼n(α).

Stretched exponentials and tensionless glass in the plaquette Ising model.

Using Monte Carlo simulations, we show that the autocorrelation function C(t) in the d = 3 Ising model with a plaquette interaction has a stretched-exponential decay in a supercooled liquid phase. Such a decay characterizes also some ground-state probability distributions obtained from the numerically exact counting of up to 10(450) configurations. A related model with a strongly degenerate ground state but lacking glassy features does not exhibit such a decay.

Critical behavior of a tumor growth model: directed percolation with a mean-field flavor.

We examine the critical behavior of a lattice model of tumor growth where supplied nutrients are correlated with the distribution of tumor cells. Our results support the previous report [Ferreira et al., Phys.

Survival rate of Suid herpesvirus (SuHV-1, Aujeszky's disease virus, ADV) in composted sewage sludge.

Sewage sludge constitutes a source of valuable biogenic raw materials, but it is a carrier of many pathogenic microorganisms and viruses. Subjected to an effective sanitization by means of the process of composting, it is suitable to use in agriculture as fertilizers. The aim of this study was to observe the survival rate of Suid Herpesvirus under the influence of the temperature alone (water bath) as well as in sewage sludge subjected to the process of composting (pile).

Naming game on adaptive weighted networks.

We examine a naming game on an adaptive weighted network. A weight of connection for a given pair of agents depends on their communication success rate and determines the probability with which the agents communicate. In some cases, depending on the parameters of the model, the preference toward successfully communicating agents is essentially negligible and the model behaves similarly to the naming game on a complete graph.

Statistical mechanics model of angiogenic tumor growth.

We examine a lattice model of tumor growth where the survival of tumor cells depends on the supplied nutrients. When such a supply is random, the extinction of tumors belongs to the directed percolation universality class. However, when the supply is correlated with the distribution of tumor cells, which as we suggest might mimic the angiogenic growth, the extinction shows different critical behavior.

Diffusive behavior of a greedy traveling salesman.

Using Monte Carlo simulations we examine the diffusive properties of the greedy algorithm in the d-dimensional traveling salesman problem. Our results show that for d=3 and 4 the average squared distance from the origin (r(2)) is proportional to the number of steps t. In the d=2 case such a scaling is modified with some logarithmic corrections, which might suggest that d=2 is the critical dimension of the problem.