Evolutionarily Stable Strategies in Quantum Games

Evolutionarily Stable Strategy (ESS) in classical game theory is a refinement of Nash equilibrium concept. We investigate the consequences when a small group of mutants using quantum strategies try to invade a classical ESS in a population engaged in symmetric bimatrix game of Prisoner's Dilemma. Secondly we show that in an asymmetric quantum game between two players an ESS pair can be made to appear or disappear by resorting to entangled or unentangled initial states used to play the game even when the strategy pair remains a Nash equilibrium in both forms of the game.Comment: RevTex,contents extended to include asymmetric games,no figur

Evolutionary Markovian Strategies in 2 x 2 Spatial Games

Evolutionary spatial 2 x 2 games between heterogeneous agents are analyzed using different variants of cellular automata (CA). Agents play repeatedly against their nearest neighbors 2 x 2 games specified by a rescaled payoff matrix with two parameteres. Each agent is governed by a binary Markovian strategy (BMS) specified by 4 conditional probabilities [p_R, p_S, p_T, p_P] that take values 0 or 1. The initial configuration consists in a random assignment of "strategists" among the 2^4= 16 possible BMS. The system then evolves within strategy space according to the simple standard rule: each agent copies the strategy of the neighbor who got the highest payoff. Besides on the payoff matrix, the dominant strategy -and the degree of cooperation- depend on i) the type of the neighborhood (von Neumann or Moore); ii) the way the cooperation state is actualized (deterministically or stochastichally); and iii) the amount of noise measured by a parameter epsilon. However a robust winner strategy is [1,0,1,1].Comment: 18 pages, 8 figures (7 of these figures contain 4 encapsulapted poscript files each

A study of the quantitative formation of furfural from d-lyxose

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1939.MIT copy bound with: Reactions of β-ionone / by Ida Rovno [1939]Includes bibliographical references (leaf [28]).by Maynard E. Smith.B.S

Mobility, fitness collection, and the breakdown of cooperation

The spatial arrangement of individuals is thought to overcome the dilemma of cooperation: When cooperators engage in clusters, they might share the benefit of cooperation while being more protected against noncooperating individuals, who benefit from cooperation but save the cost of cooperation. This is paradigmatically shown by the spatial prisoner's dilemma model. Here, we study this model in one and two spatial dimensions, but explicitly take into account that in biological setups, fitness collection and selection are separated processes occurring mostly on vastly different time scales. This separation is particularly important to understand the impact of mobility on the evolution of cooperation. We find that even small diffusive mobility strongly restricts cooperation since it enables noncooperative individuals to invade cooperative clusters. Thus, in most biological scenarios, where the mobility of competing individuals is an irrefutable fact, the spatial prisoner's dilemma alone cannot explain stable cooperation, but additional mechanisms are necessary for spatial structure to promote the evolution of cooperation. The breakdown of cooperation is analyzed in detail. We confirm the existence of a phase transition, here controlled by mobility and costs, which distinguishes between purely cooperative and noncooperative absorbing states. While in one dimension the model is in the class of the voter model, it belongs to the directed percolation universality class in two dimensions. DOI: 10.1103/PhysRevE.87.04271

Evolutionary Stability of Ecological Hierarchy

A self-similar hierarchical solution that is both dynamically and evolutionarily stable is found to the multi dimensional Lotka-Volterra equation with a single chain of prey-predator relations. This gives a simple and natural explanation to the key features of hierarchical ecosystems, such as its ubiquity, pyramidal population distribution, and higher aggressiveness among higher trophic levels. pacs{87.23.Kg, 89.75.Da, 05.45.-a} keywords{Lotka-Volterra equation, Trophic pyramid, Self-similarity}Comment: 4 Pages RevTeX4, 1 Fig, 1 Table, shortened by publishers reques

catena-Poly[[[diaqua­(nitrato-κ2 O,O′)(2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)ytterbium(III)]-μ-cyanido-κ2 N:C-[dicyanido­platinum(II)]-μ-cyanido-κ2 C:N] acetonitrile monosolvate]

The title compound, {[PtYb(CN)4(NO3)(C15H11N3)(H2O)2]·CH3CN}n, was isolated from solution as a one-dimensional coordination polymer. The Yb3+ site has ninefold coordination with a distorted tricapped trigonal–prismatic geometry, while the PtII ion is coordinated by four cyanide groups in an almost regular square-planar geometry. cis-Bridging by the tetra­cyanidoplatinate(II) anions links the Yb3+ cations, forming chains. Additionally, each Yb3+ is coordinated by two water mol­ecules, one bidentate nitrate anion, and one tridentate 2,2′:6′,2′′-terpyridine mol­ecule. O—H⋯N hydrogen-bonding inter­actions are found between adjacent chains and help to consolidate the crystal packing. In addition, π–π stacking inter­actions exist between the terpyridine ligand and the two corresponding terpyridine ligands along the adjacent chain (average inter­planar distance = 3.667 Å). Moderate Pt⋯Pt inter­actions [3.5033 (4) Å] are observed in the structure

Prisoner's Dilemma cellular automata revisited: evolution of cooperation under environmental pressure

We propose an extension of the evolutionary Prisoner's Dilemma cellular automata, introduced by Nowak and May \cite{nm92}, in which the pressure of the environment is taken into account. This is implemented by requiring that individuals need to collect a minimum score $U_{min}$, representing indispensable resources (nutrients, energy, money, etc.) to prosper in this environment. So the agents, instead of evolving just by adopting the behaviour of the most successful neighbour (who got $U^{msn}$), also take into account if $U^{msn}$ is above or below the threshold $U_{min}$. If $U^{msn}<U_{min}$ an individual has a probability of adopting the opposite behaviour from the one used by its most successful neighbour. This modification allows the evolution of cooperation for payoffs for which defection was the rule (as it happens, for example, when the sucker's payoff is much worse than the punishment for mutual defection). We also analyse a more sophisticated version of this model in which the selective rule is supplemented with a "win-stay, lose-shift" criterion. The cluster structure is analyzed and, for this more complex version we found power-law scaling for a restricted region in the parameter space.Comment: 15 pages, 8 figures; added figures and revised tex

Novel antibiotics from DNA adenine methyltransferase inhibitors

DNA adenine methylation plays a role in several core bacterial processes, including DNA mismatch repair, the timing of DNA replication and gene expression. The dependence of bacterial virulence on the activity of Dam, an adenine methyltransferase, makes it an attractive target for novel antibiotics. Dam from Yersinia pestis, the plague causing bacteria, was expressed and purified by nickel affinity chromatography. A plasmid containing the methylation sensitive restriction endonuclease dpnI gene was assembled. DpnI was expressed and purified by nickel affinity chromatography. A Y. pestis Dam activity assay, which relied on the sensitivity of DpnI to DNA methylation, was developed. This continuous fluorescence based assay was used to determine several kinetic parameters of the enzyme. The assay was validated for use in a high throughput 96-well format and used to screen a library of one thousand compounds for Y. pestis Dam inhibitors. Several compounds of interest were identified. These compounds were synthesised, re-tested for activity against Dam, counter- screened against the restriction endonuclease DpnI and assayed for an ability to bind DNA. A plasmid encoding Dam from the hyperthermophile Pyrococcus horikoshii was assembled. Wild type P. horikoshii Dam was expressed and purified by nickel affinity chromatography. The resultant Dam was contaminated by a product of mis-initiation of translation at an internal methionine codon. Site directed mutagenesis was undertaken to replace the problematic codon in the dam gene. Mutant P. horikoshii Dam was expressed and purified by nickel affinity chromatography. This hyperthermophilic enzyme was used in the development of a direct and continuous fluorescence based assay for Dam activity. Several kinetic parameters of P. horikoshii Dam were determined with the direct assa

Altruistic Duality in Evolutionary Game Theory

A game-theoretic model of social preference and enlightened self-interest is formulated. Existence of symmetry and duality in the game matrices with altruistic social preference is revealed. The model is able to quantitatively describe the dynamical evolution of altruism in prisoner's dilemma and the regime change in prey-predator dynamics.Comment: ReVTeX4, 4 papes, 2 ifigures, Typos corrected for publicatio