Phase transitions for rock-scissors-paper game on different networks

Monte Carlo simulations and dynamical mean-field approximations are performed to study the phase transitions in rock-scissors-paper game on different host networks. These graphs are originated from lattices by introducing quenched and annealed randomness simultaneously. In the resulting phase diagrams three different stationary states are identified for all structures. The comparison of results on different networks suggests that the value of clustering coefficient plays an irrelevant role in the emergence of a global oscillating phase. The critical behavior of phase transitions seems to be universal and can be described by the same exponents.Comment: 4 pages, 4 figures, to be published in PR

Molecular analysis of S-haplotypes in peach, a self-compatible Prunus species

The most commercially grown peach [Prunus persica (L.) Batsch.] cultivars do not require cross-pollination for reasonable fruit set; however, self-incompatibility is a well-known feature within the Prunoideae subfamily. Isoelectric focusing and native polyacrylamide gel electrophoresis of S-ribonucleases; PCR analyses of S-RNase and S-haplotype-specific F-box genes as well as DNA sequencing were carried out to survey the self- (in)compatibility allele pool and to uncover the nature of self-compatibility in peach. From 25 cultivars and hybrids with considerable diversity in phenotype and origin, only two S-haplotypes were detected. Allele identity could be checked by exact length determination of the PCR-amplified fragments and/or partial sequencing of the peach S-1-, S-2-, and Prunus davidiana (Carr.) Franch. S-1 RNases. S-RNases of peach were detected to possess ribonuclease activity, and a single nucleotide polymorphism in the S,-RNase was shown, which represents a synonymous substitution and does not change the amino acid present at the position in the protein. A 700-bp fragment of the peach SFB gene was PCR-amplified, which is similar to the fragment size of functional Prunus L. SFBs. All data obtained in this study may support the contribution of genes outside the S-locus to the self-compatible phenotype of peaches

Spreading of families in cyclic predator-prey models

We study the spreading of families in two-dimensional multispecies predator-prey systems, in which species cyclically dominate each other. In each time step randomly chosen individuals invade one of the nearest sites of the square lattice eliminating their prey. Initially all individuals get a family-name which will be carried on by their descendants. Monte Carlo simulations show that the systems with several species (N=3,4,5) are asymptotically approaching the behavior of the voter model, i.e., the survival probability of families, the mean-size of families and the mean-square distance of descendants from their ancestor exhibit the same scaling behavior. The scaling behavior of the survival probability of families has a logarithmic correction. In case of the voter model this correction depends on the number of species, while cyclic predator-prey models behave like the voter model with infinite species. It is found that changing the rates of invasions does not change this asymptotic behavior. As an application a three-species system with a fourth species intruder is also discussed.Comment: to be published in PR

Segregation process and phase transition in cyclic predator-prey models with even number of species

We study a spatial cyclic predator-prey model with an even number of species (for n=4, 6, and 8) that allows the formation of two defective alliances consisting of the even and odd label species. The species are distributed on the sites of a square lattice. The evolution of spatial distribution is governed by iteration of two elementary processes on neighboring sites chosen randomly: if the sites are occupied by a predator-prey pair then the predator invades the prey's site; otherwise the species exchange their site with a probability $X$. For low $X$ values a self-organizing pattern is maintained by cyclic invasions. If $X$ exceeds a threshold value then two types of domains grow up that formed by the odd and even label species, respectively. Monte Carlo simulations indicate the blocking of this segregation process within a range of X for n=8.Comment: 5 pages, 5 figures, to be appear in Phys. Rev.

Vertex dynamics during domain growth in three-state models

Topological aspects of interfaces are studied by comparing quantitatively the evolving three-color patterns in three different models, such as the three-state voter, Potts and extended voter models. The statistical analysis of some geometrical features allows to explore the role of different elementary processes during distinct coarsening phenomena in the above models.Comment: 4 pages, 5 figures, to be published in PR

Male gender predisposes to development of endotoxic shock in the rat

Objective: After intravenous (i.v.) injection of lipopolysaccharide (LPS) macrophages release nitric oxide (NO) due to the expression of the inducible NO synthase (iNOS). After LPS NO is abundantly produced also in the cardiovascular system and may contribute to the development of hypotension and shock. Since the immune response, the synthesis of NO and the regulation of blood pressure (BP) differ between males and females, in the present study the effect of LPS on BP, renal function, the plasma and urinary concentration of the metabolites of NO as well as the splenic and aortic expression of the iNOS gene were compared between male and female rats. Methods: BP and renal function were measured in anesthetized rats following the i.v. injection of LPS (E. coli, 4 mg/kg). The NOx and NOx (metabolites of NO=NOx) concentration was measured by the Griess reaction. The iNOS gene expression was studied by RT-PCR. Results: Four hours after LPS, BP of males (n=9) was reduced by 63+/-12 mmHg versus 10+/-4 in females (n=7, P<0.005). Aminoguanidine, a selective inhibitor of iNOS, prevented the reduction of BP in males. The plasma concentration of NOx (P-NOx, mu M) was lower in hypotensive males (128+/-20) than in normotensive females (235+/-29, P<0.005). Males also exhibited lower urinary NO, excretion (UNOxV) after LPS (P<0.001 vs, females). Prior castration of males provided protection against hypotension (fall of BP: -4+/-4 mmHg, n=6, P<0.02 versus males) and resulted in higher P-NOx as well as UNOxV (both P<0.001 versus males and not different from females). Prior ovariectomy (n=5) had no influence on the hemodynamic and NOx response to LPS. Male rats displayed enhanced aortic iNOS/beta-actin ratio relative to females after LPS (n=3 in each group, P<0.05). Conclusions: (1) Male gender may sensitize to LPS-induced shock and (2) sensitivity of males to endotoxin is associated with an attenuated, not exaggerated total rate of NO synthesis

Evolutionary Prisoner's Dilemma game on the Newman-Watts networks

Maintenance of cooperation was studied for a two-strategy evolutionary Prisoner's Dilemma game where the players are located on a one-dimensional chain and their payoff comes from games with the nearest and next-nearest neighbor interactions. The applied host geometry makes possible to study the impacts of two conflicting topological features. The evolutionary rule involves some noise affecting the strategy adoptions between the interacting players. Using Monte Carlo simulations and the extended versions of dynamical mean-field theory we determined the phase diagram as a function of noise level and a payoff parameter. The peculiar feature of the diagram is changed significantly when the connectivity structure is extended by extra links as suggested by Newman and Watts.Comment: 4 figure

Restricted connections among distinguished players support cooperation

We study the evolution of cooperation within the spatial prisoner's dilemma game on a square lattice where a fraction of players $\mu$ can spread their strategy more easily than the rest due to a predetermined larger teaching capability. In addition, players characterized with the larger teaching capability are allowed to temporarily link with distant opponents of the same kind with probability $p$, thus introducing shortcut connections among the distinguished. We show that these additional temporary connections are able to sustain cooperation throughout the whole range of the temptation to defect. Remarkably, we observe that as the temptation to defect increases the optimal $\mu$ decreases, and moreover, only minute values of $p$ warrant the best promotion of cooperation. Our study thus indicates that influential individuals must be few and sparsely connected in order for cooperation to thrive in a defection prone environment.Comment: 6 two-column pages, 6 figures; accepted for publication in Physical Review

Cluster mean-field study of the parity conserving phase transition

The phase transition of the even offspringed branching and annihilating random walk is studied by N-cluster mean-field approximations on one-dimensional lattices. By allowing to reach zero branching rate a phase transition can be seen for any N <= 12.The coherent anomaly extrapolations applied for the series of approximations results in $\nu_{\perp}=1.85(3)$ and $\beta=0.96(2)$.Comment: 6 pages, 5 figures, 1 table included, Minor changes, scheduled for pubication in PR