Dynamically generated cyclic dominance in spatial prisoner's dilemma games

We have studied the impact of time-dependent learning capacities of players in the framework of spatial prisoner's dilemma game. In our model, this capacity of players may decrease or increase in time after strategy adoption according to a step-like function. We investigated both possibilities separately and observed significantly different mechanisms that form the stationary pattern of the system. The time decreasing learning activity helps cooperator domains to recover the possible intrude of defectors hence supports cooperation. In the other case the temporary restrained learning activity generates a cyclic dominance between defector and cooperator strategies, which helps to maintain the diversity of strategies via propagating waves. The results are robust and remain valid by changing payoff values, interaction graphs or functions characterizing time-dependence of learning activity. Our observations suggest that dynamically generated mechanisms may offer alternative ways to keep cooperators alive even at very larger temptation to defect.Comment: 7 pages, 6 figures, accepted for publication in Physical Review

Shear-Induced Heterogeneity in Associating Polymer Gels: Role of Network Structure and Dilatancy

We study associating polymer gels under steady shear using Brownian dynamics simulation to explore the interplay between the network structure, dynamics, and rheology. For a wide range of flow rates, we observe the formation of shear bands with a pronounced difference in shear rate, concentration, and structure. A striking increase in the polymer pressure in the gradient direction with shear, along with the inherently large compressibility of the gels, is shown to be a crucial factor in destabilizing homogeneous flow through shear-gradient concentration coupling. We find that shear has only a modest influence on the degree of association, but induces marked spatial heterogeneity in the network connectivity. We attribute the increase in the polymer pressure (and polymer mobility) to this structural reorganization

Study the Heavy Molecular States in Quark Model with Meson Exchange Interaction

Some charmonium-like resonances such as X(3872) can be interpreted as possible $D^{(*)}D^{(*)}$ molecular states. Within the quark model, we study the structure of such molecular states and the similar $B^{(*)}B^{(*)}$ molecular states by taking into account of the light meson exchange ($\pi$, $\eta$, $\rho$, $\omega$ and $\sigma$) between two light quarks from different mesons

A method for high-quality RNA extraction from tall fescue

The isolation of high-quality RNA was a precondition in molecular biology research of tall fescue. Two common approaches were adopted for the total RNA extraction by using leaves of tall fescue as the material in this experiment in order to seek the optimized total RNA extraction method of tall fescue, as well as the improvement of the extraction method used by the predecessors. The results showed that the Trizol method cost much and was not suitable for the large quantity of plant tissues extraction. The traditional isothiocyanate method resulted in protein contamination and RNA degradation. By employing the improved isothiocyanate method, we found that there were three bright bands in agarose gel electrophoresis (28S rRNA, 18S rRNA and 5S rRNA). The band of 28S rRNA was brighter than that of 18S rRNA, and the value of OD260/OD280 was 1.8 to 2.0. Clear bands and high polymorphisms were obtained by cDNA-AFLP analysis. These results indicated that the RNA isolated by the improved isothiocyanate method had a good integrity and high purity, which could be used for the later molecular researches.Key words: Tall fescue, RNA extraction, improved isothiocyanate method

Stabilization of a Coupled Second Order ODE-wave System

This paper considers the stabilization of a coupled second order ODE-wave system, where the ODE dynamics contain the solution of the wave equation at an intermediate point. We design a stabilizing feedback controller by choosing a suitable target system and backstepping transformation. The backstepping transformation is defined in terms of several kernel functions, for which we establish existence, uniqueness and smoothness properties. We also prove exponential stability for the resulting closed-loop system. Finally, the effectiveness of the proposed feedback controller is verified via a numerical example

Neutralizing Antibody Response to Hepatitis C Virus

A critical first step in a “rational vaccine design” approach for hepatitis C virus (HCV) is to identify the most relevant mechanisms of immune protection. Emerging evidence provides support for a protective role of virus neutralizing antibodies, and the ability of the B cell response to modify the course of acute HCV infection. This has been made possible by the development of in vitro cell culture models, based on HCV retroviral pseudotype particles expressing E1E2 and infectious cell culture-derived HCV virions, and small animal models that are robust tools in studies of antibody-mediated virus neutralization. This review is focused on the immunogenic determinants on the E2 glycoprotein mediating virus neutralization and the pathways in which the virus is able to escape from immune containment. Encouraging findings from recent studies provide support for the existence of broadly neutralization antibodies that are not associated with virus escape. The identification of conserved epitopes mediating virus neutralization that are not associated with virus escape will facilitate the design of a vaccine immunogen capable of eliciting broadly neutralizing antibodies against this highly diverse virus

X-ray Observation and Analysis of The Composite Supernova Remnant G327.1-1.1

Based on the data from the observation of the SNR G327.1-1.1 by ASCA and ROSAT, we find that G327.1-1.1 is a composite remnant with both a nonthermal emission component and a diffuse thermal emission component. The nonthermal component is well fitted by a power-law model with photon index about 2.2. This component is attributed to the emission from the synchrotron nebula powered by an undiscovered central pulsar. The thermal component has a temperature of about 0.4 keV. We attribute it to the emission from the shock-heat swept-up ISM. Its age, explosion energy and density of ambient medium are derived from the observed thermal component. Some charactistics about the synchrotron nebula are also derived. We search for the pulsed signal, but has not found it. The soft X-ray(0.4 - 2 keV) and hard X-ray(2 - 10 keV) images are different, but they both elongate in the SE-NW direction. And this X-ray SE-NW elongation is in positional coincidence with the radio ridge in MOST 843MHz radio map. We present a possibility that the X-ray nonthermal emission mainly come from the trail produced by a quickly moving undiscoverd pulsar, and the long radio ridge is formed when the pulsar is moving out of the boundary of the plerionic structure.Comment: 20 pages, 4 Postscript figures, aasms4.sty and psfig.sty, to be published in Astrophysical Journal, January 20, 1999, Vol. 51

Topological Forces in a Model System for Reptation Dynamics

We construct a micromechanical version of an early model for topologically constrained polymers -- a 2D chain amongst point-like uncrossable obstacles -- which allows us to explicitly elucidate the role of topological forces beyond confining the chain to a curvilinear tube-like path. Our simulations reveal that linear relaxation of the contour length \textit{along the tube} is slowed down by the presence of topological forces that can be considered as additional effective topological ``friction'' in quiescence. However, this perspective fails in predicting the strong forces that resist the imposed curvilinear motion of the chain during nonlinear startup microrheology. These entropic forces are nonlocal in nature and result from an unexpected coupling between orientational and longitudinal dynamics.Comment: Comments welcom