GA hardness and interdependence between genes in the chromosome are important questions in the study of genetic algorithms(GA). Traditional methods, which are used to measure the interaction between genes, can only re...GA hardness and interdependence between genes in the chromosome are important questions in the study of genetic algorithms(GA). Traditional methods, which are used to measure the interaction between genes, can only reflect the extent of epistasis between all genes in the chromosome. Therefore, the definition of the fitness landscape of schemata is proposed in this paper, and epistasis measures on this landscape of schemata are used to analyze the degree of interdependence between some certain gene loci in study. Some information between these sites can be reflected by some characters of the fitness landscape of schemata which are composed of these fixed sites. The stronger the interaction between these sites, the larger the variation of the fitness of schemata whose fixed sites correspond to those sites in study, and the more rugged the fitness landscape of these schemata. According to the degree of interaction between these given gene loci, building blocks of GA can be analyzed and determined, and further genetic operators and the structure of GA can be designed and adjusted to improve the performance of GA. At last, a lot of experiments including NK models are done, and results of empirical analysis show that this method is effective.展开更多
Considering time-dependence of both interactions and external potential,we analytically study the collisional behaviors of two bright solitons in Bose-Einstein condensates by using Darboux transformation.It is found t...Considering time-dependence of both interactions and external potential,we analytically study the collisional behaviors of two bright solitons in Bose-Einstein condensates by using Darboux transformation.It is found that for a closed external potential,the soliton-soliton distance is decreased with nonlinearly increased interactions,while the amplitude of each soliton increases and its width decreases.For linearly increased interactions but nonlinearly decreased external potential,especially,the atom transfer between two solitons is observed,different from previous theory of no atom transfer in solitons collision in a fixed external potential.In addition,it is shown that the collisional type,such as head-on,"chase",or collision period between two solitons,can be controlled by tuning both interactions and external potential.The predicted phenomena can be observed under the condition of the current experiments and open possibilities for future application in atoms transport.展开更多
Aims The limitations of classical Lotka–Volterra models for analyzing and interpreting competitive interactions among plant species have become increasingly clear in recent years.Three of the problems that have been ...Aims The limitations of classical Lotka–Volterra models for analyzing and interpreting competitive interactions among plant species have become increasingly clear in recent years.Three of the problems that have been identified are(i)the absence of frequency-dependence,which is important for long-term coexistence of species,(ii)the need to take unmeasured(often unmeasurable)variables influencing individual performance into account(e.g.spatial variation in soil nutrients or pathogens)and(iii)the need to separate measurement error from biological variation.Methods We modified the classical Lotka–Volterra competition models to address these limitations.We fitted eight alternative models to pin-point cover data on Festuca ovina and Agrostis capillaris over 3 years in an herbaceous plant community in Denmark.A Bayesian modeling framework was used to ascertain whether the model amendments improve the performance of the models and increase their ability to predict community dynamics and to test hypotheses.Important Findings Inclusion of frequency-dependence and measurement error,but not unmeasured variables,improved model performance greatly.Our results emphasize the importance of comparing alternative models in quantitative studies of plant community dynamics.Only by considering possible alternative models can we identify the forces driving community assembly and change,and improve our ability to predict the behavior of plant communities.展开更多
In this paper, with the method of adaptive dynamics, we investigate the coevolution of phenotypic traits of predator and prey species. The evolutionary model is constructed from a deterministic approximation of the un...In this paper, with the method of adaptive dynamics, we investigate the coevolution of phenotypic traits of predator and prey species. The evolutionary model is constructed from a deterministic approximation of the underlying stochastic ecological processes. Firstly, we investigate the ecological and evolutionary conditions that allow for continu- ously stable strategy and evolutionary branching. We find that evolutionary branching in the prey phenotype will occur when the frequency dependence in the prey carrying capacity is not strong. Furthermore, it is found that if the two prey branches move far away enough, the evolutionary branching in the prey phenotype will induce the sec- ondary branching in the predator phenotype. The final evolutionary outcome contains two prey and two predator species. Secondly, we show that under symmetric interactions the evolutionary model admits a supercritical Hopf bifurcation if the frequency depen- dence in the prey carrying capa.city is very weak. Evolutionary cycle is a likely outcome of the nmtation-selection processes. Finally, we find that frequency-dependent selection can drive the predator population to extinction under asymmetric interactions.展开更多
In the mean field approximation of nonlinear relativistic a-ω-p model, we have studied the influence of density-dependent coupling constants between nucleons and mesons on the equation of state （EOS） of infinite sy...In the mean field approximation of nonlinear relativistic a-ω-p model, we have studied the influence of density-dependent coupling constants between nucleons and mesons on the equation of state （EOS） of infinite symmetric nuclear matter in different conditions. We find that the EOS of nuclear matter will become stiffer as e, d in the self- interaction of σ meson increase when the coeffcients except aω in Гω, in which the opposite occurs, are fixed. On the other hand, greater values of aσ, bσ, cσ, aω, dω and smaller values of dσ, bω, cω will lead to stiffer EOS ifc and d are fixed. Besides, greater values of Гω lead to stiffer EOS in high density region for the EOS with same incompressibility coefficient at saturation density.展开更多
文摘GA hardness and interdependence between genes in the chromosome are important questions in the study of genetic algorithms(GA). Traditional methods, which are used to measure the interaction between genes, can only reflect the extent of epistasis between all genes in the chromosome. Therefore, the definition of the fitness landscape of schemata is proposed in this paper, and epistasis measures on this landscape of schemata are used to analyze the degree of interdependence between some certain gene loci in study. Some information between these sites can be reflected by some characters of the fitness landscape of schemata which are composed of these fixed sites. The stronger the interaction between these sites, the larger the variation of the fitness of schemata whose fixed sites correspond to those sites in study, and the more rugged the fitness landscape of these schemata. According to the degree of interaction between these given gene loci, building blocks of GA can be analyzed and determined, and further genetic operators and the structure of GA can be designed and adjusted to improve the performance of GA. At last, a lot of experiments including NK models are done, and results of empirical analysis show that this method is effective.
基金Supported by National Natural Science Foundation of China under Grant Nos.51032002 and 11074212Foundation for the Author of National Excellent Doctoral Dissertation of China under Grant No.200726+1 种基金the key Project of the National HighTechnology Research and Development Program ("863" Program) of China under Grant No.2011AA050526Hunan Provincial Innovation Foundation for Postgraduate under Grant No.CX2010B254
文摘Considering time-dependence of both interactions and external potential,we analytically study the collisional behaviors of two bright solitons in Bose-Einstein condensates by using Darboux transformation.It is found that for a closed external potential,the soliton-soliton distance is decreased with nonlinearly increased interactions,while the amplitude of each soliton increases and its width decreases.For linearly increased interactions but nonlinearly decreased external potential,especially,the atom transfer between two solitons is observed,different from previous theory of no atom transfer in solitons collision in a fixed external potential.In addition,it is shown that the collisional type,such as head-on,"chase",or collision period between two solitons,can be controlled by tuning both interactions and external potential.The predicted phenomena can be observed under the condition of the current experiments and open possibilities for future application in atoms transport.
文摘Aims The limitations of classical Lotka–Volterra models for analyzing and interpreting competitive interactions among plant species have become increasingly clear in recent years.Three of the problems that have been identified are(i)the absence of frequency-dependence,which is important for long-term coexistence of species,(ii)the need to take unmeasured(often unmeasurable)variables influencing individual performance into account(e.g.spatial variation in soil nutrients or pathogens)and(iii)the need to separate measurement error from biological variation.Methods We modified the classical Lotka–Volterra competition models to address these limitations.We fitted eight alternative models to pin-point cover data on Festuca ovina and Agrostis capillaris over 3 years in an herbaceous plant community in Denmark.A Bayesian modeling framework was used to ascertain whether the model amendments improve the performance of the models and increase their ability to predict community dynamics and to test hypotheses.Important Findings Inclusion of frequency-dependence and measurement error,but not unmeasured variables,improved model performance greatly.Our results emphasize the importance of comparing alternative models in quantitative studies of plant community dynamics.Only by considering possible alternative models can we identify the forces driving community assembly and change,and improve our ability to predict the behavior of plant communities.
文摘In this paper, with the method of adaptive dynamics, we investigate the coevolution of phenotypic traits of predator and prey species. The evolutionary model is constructed from a deterministic approximation of the underlying stochastic ecological processes. Firstly, we investigate the ecological and evolutionary conditions that allow for continu- ously stable strategy and evolutionary branching. We find that evolutionary branching in the prey phenotype will occur when the frequency dependence in the prey carrying capacity is not strong. Furthermore, it is found that if the two prey branches move far away enough, the evolutionary branching in the prey phenotype will induce the sec- ondary branching in the predator phenotype. The final evolutionary outcome contains two prey and two predator species. Secondly, we show that under symmetric interactions the evolutionary model admits a supercritical Hopf bifurcation if the frequency depen- dence in the prey carrying capa.city is very weak. Evolutionary cycle is a likely outcome of the nmtation-selection processes. Finally, we find that frequency-dependent selection can drive the predator population to extinction under asymmetric interactions.
基金Supported by the National Natural Science Foundation of China under Grant No.11275073
文摘In the mean field approximation of nonlinear relativistic a-ω-p model, we have studied the influence of density-dependent coupling constants between nucleons and mesons on the equation of state （EOS） of infinite symmetric nuclear matter in different conditions. We find that the EOS of nuclear matter will become stiffer as e, d in the self- interaction of σ meson increase when the coeffcients except aω in Гω, in which the opposite occurs, are fixed. On the other hand, greater values of aσ, bσ, cσ, aω, dω and smaller values of dσ, bω, cω will lead to stiffer EOS ifc and d are fixed. Besides, greater values of Гω lead to stiffer EOS in high density region for the EOS with same incompressibility coefficient at saturation density.
