Correlated adaptation of agents in a simple market: a statistical physics perspective

We discuss recent work in the study of a simple model for the collective behaviour of diverse speculative agents in an idealized stockmarket, considered from the perspective of the statistical physics of many-body systems. The only information about other agents available to any one is the total trade at time steps. Evidence is presented for correlated adaptation and phase transitions/crossovers in the global volatility of the system as a function of appropriate information scaling dimension. Stochastically controlled irrationally of individual agents is shown to be globally advantageous. We describe the derivation of the underlying effective stochastic differential equations which govern the dynamics, and make an interpretation of the results from the point of view of the statistical physics of disordered systems.Comment: 15 Pages. 5 figure

Influence of interstellar and atmospheric extinction on light curves of eclipsing binaries

Interstellar and atmospheric extinctions redden the observational photometric data and they should be handled rigorously. This paper simulates the effect of reddening for the modest case of two main sequence T1 = 6500K and T2 = 5500K components of a detached eclipsing binary system. It is shown that simply subtracting a constant from measured magnitudes (the approach often used in the field of eclipsing binaries) to account for reddening should be avoided. Simplified treatment of the reddening introduces systematics that reaches \~0.01mag for the simulated case, but can be as high as ~0.2mag for e.g. B8V--K4III systems. With rigorous treatment, it is possible to uniquely determine the color excess value E(B-V) from multi-color photometric light curves of eclipsing binaries.Comment: 6 pages, 9 figures, 1 table, Kopal's Binary Star Legacy conference contribution (Litomysl 2004), to be published by Kluwer A&S

Emergence of pulled fronts in fermionic microscopic particle models

We study the emergence and dynamics of pulled fronts described by the Fisher-Kolmogorov-Petrovsky-Piscounov (FKPP) equation in the microscopic reaction-diffusion process A + A A$ on the lattice when only a particle is allowed per site. To this end we identify the parameter that controls the strength of internal fluctuations in this model, namely, the number of particles per correlated volume. When internal fluctuations are suppressed, we explictly see the matching between the deterministic FKPP description and the microscopic particle model.Comment: 4 pages, 4 figures. Accepted for publication in Phys. Rev. E as a Rapid Communicatio

How do we drive a renaissance for national island conservation in Australia?

Australia’s approach to managing and conserving its offshore islands as important national assets warrants urgent review. There is a growing realisation that the current trajectory of loss of natural heritage on islands must be reversed, particularly in an era of increasing climate change. We propose a role description and an organisational model for a national Australian Islands Alliance that champions conservation action, prioritises investments aligned to risks, and that connects partners at a strategic national level. A national alliance offers important opportunity to assess threats and report on condition. Four key foundations underpin a national alliance dedicated to championing island care and expert management: (1) management informed by evidence; (2) sound return on investment; (3) national coordination in partnership with States and Territories; and (4) community participation inclusive of Aboriginal peoples’ and Torres Strait Islanders’ custodial rights and interests. The message from experiences shared across Australia, New Zealand and the Pacific region is that traditional island custodians and stakeholders are vital partners to restoration efforts. These shared learnings collectively demonstrate the time is now for Australia to move forward with a respectful and unified direction to progress successful and sustainable island conservation and restoration

Continuous transition of social efficiencies in the stochastic strategy Minority Game

We show that in a variant of the Minority Game problem, the agents can reach a state of maximum social efficiency, where the fluctuation between the two choices is minimum, by following a simple stochastic strategy. By imagining a social scenario where the agents can only guess about the number of excess people in the majority, we show that as long as the guess value is sufficiently close to the reality, the system can reach a state of full efficiency or minimum fluctuation. A continuous transition to less efficient condition is observed when the guess value becomes worse. Hence, people can optimize their guess value for excess population to optimize the period of being in the majority state. We also consider the situation where a finite fraction of agents always decide completely randomly (random trader) as opposed to the rest of the population that follow a certain strategy (chartist). For a single random trader the system becomes fully efficient with majority-minority crossover occurring every two-days interval on average. For just two random traders, all the agents have equal gain with arbitrarily small fluctuations.Comment: 8 pages, 6 fig

Three-body description of direct nuclear reactions: Comparison with the continuum discretized coupled channels method

The continuum discretized coupled channels (CDCC) method is compared to the exact solution of the three-body Faddeev equations in momentum space. We present results for: i) elastic and breakup observables of d-12C at E_d=56 MeV, ii) elastic scattering of d-58Ni at E_d=80 MeV, and iii) elastic, breakup and transfer observables for 11Be+p at E_{11Be}/A=38.4 MeV. Our comparative studies show that, in the first two cases, the CDCC method is a good approximation to the full three-body Faddeev solution, but for the 11Be exotic nucleus, depending on the observable or the kinematic regime, it may miss out some of the dynamic three-body effects that appear through the explicit coupling to the transfer channel.Comment: 12 pages, 10 figures, accepted for publication in Physical Review

Can public-private partnerships foster investment sustainability in smart hospitals?

This article addresses the relationship between Public-Private Partnerships (PPP) and the sustainability of public spending in smart hospitals. Smart (technological) hospitals represent long-termed investments where public and private players interact with banking institutions and eventually patients, to satisfy a core welfare need. Characteristics of smart hospitals are critically examined, together with private actors' involvement and flexible forms of remuneration. Technology-driven smart hospitals are so complicated that they may require sophisticated PPP. Public players lack innovative skills, whereas private actors seek additional compensation for their non-routine efforts and higher risk. PPP represents a feasible framework, especially if linked to Project Financing (PF) investment patterns. Whereas the social impact of healthcare investments seems evident, their financial coverage raises growing concern in a capital rationing context where shrinking public resources must cope with the growing needs of chronic elder patients. Results-Based Financing (RBF) is a pay-by-result methodology that softens traditional PPP criticalities as availability payment sustainability or risk transfer compensation. Waste of public money can consequently be reduced, and private bankability improved. In this study, we examine why and how advanced Information Technology (IT) solutions implemented in "Smart Hospitals" should produce a positive social impact by increasing at the same time health sustainability and quality of care. Patient-centered smart hospitals realized through PPP schemes, reshape traditional healthcare supply chains with savings and efficiency gains that improve timeliness and execution of care

Mind the gap: IR and the challenge of international politics

The discipline of International Relations (IR) for a long time of its history has developed in the form of Great Debates that involved competing paradigms and schools. More recently, it has been described as a cacophony of voices unable to communicate among themselves, but also incapable to provide keys to understand an ever more complex reality. This collection aims at evaluating the heuristic value of a selection of traditional paradigmsrealism and liberalism), schools (constructivism), and subdisciplines (security studies and international political economy) so as to assess the challenges before IR theory today and the ability of the discipline to provide tools to make the changed world still intelligible

Zero-Dimensional Model for Dynamic Behavior of Engineered Rubber in Automotive Applications

Abstract This paper presents a zero-dimensional model for the simulation of the mechanical behavior of automotive engineered rubber components, such as flexible couplings. The objective is to develop a real-time-capable model, able to simulate the behavior of a driveline containing elastomer components: the engineered rubber model has to correlate stretch to stress, the mechanical behavior being represented by means of a hysteresis cycle. The study presents the implementation of Maxwell and Voigt models, showing their limits in the representation of the material behavior: elastomers present a nonlinear response in the relationship stress-strain. A combination of Maxwell and Voigt models, with stiffness and damping variable according to the stress and strain rate, to represent nonlinear material responses, is coupled to a relaxation model, in order to represent the Mullins effect (the rubber mechanical behavior also depends on load history). Experimental tests have been carried out with different pre-load settings, stress amplitudes and stress frequencies. Tests results have been used to calibrate the parameters defining the simulation model, comparing the model outputs to experimental data: an optimization algorithm has been applied, with the aim of minimizing the results discrepancy with respect to experimental results. The optimization tool has been also used to reduce the number of parameters defining the model, in order to simplify the required computational power, avoiding at the same time over-parametrization. In the second section of the paper, the model is used for the simulation of a different rubber component, whose behavior is identified using quasi-static load ramps, frequency and amplitude sweeps, steps and random cycles. An alternative model formulation, minimizing the degrees of freedom is then applied to the new dataset. The model parameters are separately optimized using different tests, in order to capture the specific mechanical behavior. Finally, the identified parameters are used to simulate the elastomer response in random tests, comparing the results to experimental data, to evaluate the simulation quality in terms of RMSE