Determination of sequential best replies in n-player games by Genetic Algorithms

An iterative algorithm for establishing the Nash Equilibrium in pure strategies (NE) is proposed and tested in Cournot Game models. The algorithm is based on the convergence of sequential best responses and the utilization of a genetic algorithm for determining each player's best response to a given strategy profile of its opponents. An extra outer loop is used, to address the problem of finite accuracy, which is inherent in genetic algorithms, since the set of feasible values in such an algorithm is finite. The algorithm is tested in five Cournot models, three of which have convergent best replies sequence, one with divergent sequential best replies and one with \local NE traps"(Son and Baldick 2004), where classical local search algorithms fail to identify the Nash Equilibrium. After a series of simulations, we conclude that the algorithm proposed converges to the Nash Equilibrium, with any level of accuracy needed, in all but the case where the sequential best replies process diverges.Genetic Algorithms, Cournot oligopoly, Best Response, Nash Equilibrium

Time-varying Multi-regime Models Fitting by Genetic Algorithms

Many time series exhibit both nonlinearity and nonstationarity. Though both features have often been taken into account separately, few attempts have been proposed to model them simultaneously. We consider threshold models, and present a general model allowing for different regimes both in time and in levels, where regime transitions may happen according to self-exciting, or smoothly varying, or piecewise linear threshold modeling. Since fitting such a model involves the choice of a large number of structural parameters, we propose a procedure based on genetic algorithms, evaluating models by means of a generalized identification criterion. The performance of the proposed procedure is illustrated with a simulation study and applications to some real data.Nonlinear time series; Nonstationary time series; Threshold model

Multi-regime models for nonlinear nonstationary time series

Nonlinear nonstationary models for time series are considered, where the series is generated from an autoregressive equation whose coe±cients change both according to time and the delayed values of the series itself, switching between several regimes. The transition from one regime to the next one may be discontinuous (self-exciting threshold model), smooth (smooth transition model) or continuous linear (piecewise linear threshold model). A genetic algorithm for identifying and estimating such models is proposed, and its behavior is evaluated through a simulation study and application to temperature data and a financial index.

Coevolutionary Genetic Algorithms for Establishing Nash Equilibrium in Symmetric Cournot Games

We use co-evolutionary genetic algorithms to model the players' learning process in several Cournot models, and evaluate them in terms of their convergence to the Nash Equilibrium. The \social-learning" versions of the two co-evolutionary algorithms we introduce, establish Nash Equilibrium in those models, in contrast to the \individual learning" versions which, as we see here, do not imply the convergence of the players' strategies to the Nash outcome. When players use \canonical co-evolutionary genetic algorithms" as learning algorithms, the process of the game is an ergodic Markov Chain, and therefore we analyze simulation results using the relevant methodology, to find that in the \social" case, states leading to NE play are highly frequent at the stationary distribution of the chain, in contrast to the \individual learning" case, when NE is not reached at all in our simulations; to ftnd that the expected Hamming distance of the states at the limiting distribution from the \NE state" is significantly smaller in the \social" than in the \individual learning case"; to estimate the expected time that the \social" algorithms need to get to the \NE state" and verify their robustness and finally to show that a large fraction of the games played are indeed at the Nash Equilibrium.Genetic Algorithms, Cournot oligopoly, Evolutionary Game Theory, Nash Equilibrium

Sensitive cells: Enabling tools for static and dynamic control of microbial pathways

For the purpose of reprogramming the cellular network we employ in silico model of the genome-wide metabolism in order to predict genetic modifications that lead to increases in carbon fluxes of interest. Such Systems Biology approaches, in combination with traditional genetic engineering have resulted in robust production levels that can result in the commercially viable processes for the synthesis of important molecules. In addition to such approaches, we will also describe the engineering of both positive and negative feedback controls for dynamic tuning of metabolic flux around intracellular metabolites, such as malonyl-CoA in microorganisms using a dual transcriptional regulator. We will also demonstrate that such dynamic regulation can also be accomplished through the construction of orthogonal variants of the classic T7lac promoter using site-directed mutagenesis, generating a panel of inducible hybrid promoters regulated by both LacI and dCas9 and covering a wide expression range. Remarkably, dCas9 orthogonality in our system is mediated by only 23 nucleotide mismatches in a narrow window of the RNA:DNA hybrid, neighboring the protospacer adjacent motif (PAM). Finally, the presentation will also cover our work on the development and optimization of polycultures (three or more strains in co-culture) for the extension of recombinant pathways, such as the flavonoid branch pathway, in vivo. This technology has enabled, for the first time, the de novo production of flavan-3-ols and anthocyanins in E. coli. Utilizing a computationally guided optimization approach, we were able to demonstrate up to a 970-fold improvement over previously published monoculture titer

The management of Castleman's disease of the mediastinum: a case report

Castleman's disease or angiofollicular lymph node hyperplasia is a rare clinical entity that may present in many sites and with a variety of symptoms. We report here a case of unicentric Castleman's disease (hyaline vascular pattern) located in the mediastinum as a solitary mass. The patient was a Caucasian female 58 years old presented after incidental discovery of the mass in a x-ray. In Castleman's disease surgery is generally recommended for localised lesions to remove the mass as completely as possible reserving other treatment modalities for unresectable cases or multicentric disease

On the Thermal Environmental Quality of Typical Urban Settlement Configurations

Urban overheating and energy imbalances are severe environmental concerns. The role of urban sprawl patterns in the formation of Heat Island has recently absorbed the researchers’ interest. The research focuses on metropolitan areas with a range of urban typologies. However, there still is a knowledge gap in how UHI responds to different urban typologies. The interaction between urban configurations and heat island characteristics is explored in Sydney. A combination of terrestrial surveys and modelling techniques was implemented, and results were extracted based on simulation results. The Urban Taskforce Australia suggested the applied categorization methods that follow Stewart and Oke’s Local Climate Zones (LCZs) scheme. We assessed eleven urban designs on ambient air temperature, wind characteristics, heat intensity, and outdoor thermal comfort over three summer days. We correlated results to density and the built-up ratio in all configurations and found that the maximum configurational impact on the heat island reached 2.33 °C. Configurations with a built-up ratio between 0.37 to 0.5 present a sharp downward trend in the average wind speed value and indicate a minimum with a built-up ratio of 0.63. Wind maps present an increase in layouts with built-up ratios of 0.23 to 0.37, whereas they decreased with built-up ratios of higher than 0.43. The average temperature decrease in high-rise compact configurations was 1.12 °C per hour. This record is substantially higher than its open counterparts. The study showed the importance of urban configuration on thermal environmental quality. In addition, implementing appropriate urban design parameters is vital to mitigate heat islands and improve environmental thermal comfort in urban areas

Intraprofessional, team-based treatment planning for oral health students in the comprehensive care clinic

published_or_final_versio