A skeletochronological study was conducted for the age, longevity and growth of a Rana nigromaculata population in northeastern Sichuan, China. Of 139 specimens, 119(68 males and 51 females) exhibited distinct arreste...A skeletochronological study was conducted for the age, longevity and growth of a Rana nigromaculata population in northeastern Sichuan, China. Of 139 specimens, 119(68 males and 51 females) exhibited distinct arrested growth lines in phalanges. Age at first reproduction was found to be two years of age for males and three for females. Maximum longevity was estimated to be at least six years in males and seven years in females. Average age did not differ between males and females. Breeding females were significantly older than breeding males. Females were larger in body size and heavier in body mass than males. Age was not correlated with body size and body mass in males, but a significant correlation was found among age, body size and body mass in females. The growth curve appeared significantly different between the sexes, with a higher growth rate throughout life and a larger asymptotic size in females. Moreover, analysis of the growth model indicated that the population studied was relatively stable.展开更多
A model which describes the dynamics of an SIS epidemic in an age-structured and time dependent population is considered. The global behavior of the model with a special form for the infective force is obtained. The e...A model which describes the dynamics of an SIS epidemic in an age-structured and time dependent population is considered. The global behavior of the model with a special form for the infective force is obtained. The existence and uniqueness of the solution and nontrivial endemic equilibrium state are proved.展开更多
基金Financial support was provided by the Foundation of Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education)
文摘A skeletochronological study was conducted for the age, longevity and growth of a Rana nigromaculata population in northeastern Sichuan, China. Of 139 specimens, 119(68 males and 51 females) exhibited distinct arrested growth lines in phalanges. Age at first reproduction was found to be two years of age for males and three for females. Maximum longevity was estimated to be at least six years in males and seven years in females. Average age did not differ between males and females. Breeding females were significantly older than breeding males. Females were larger in body size and heavier in body mass than males. Age was not correlated with body size and body mass in males, but a significant correlation was found among age, body size and body mass in females. The growth curve appeared significantly different between the sexes, with a higher growth rate throughout life and a larger asymptotic size in females. Moreover, analysis of the growth model indicated that the population studied was relatively stable.
基金This work is supported by the National Natural Sciences Foundation of China.
文摘A model which describes the dynamics of an SIS epidemic in an age-structured and time dependent population is considered. The global behavior of the model with a special form for the infective force is obtained. The existence and uniqueness of the solution and nontrivial endemic equilibrium state are proved.
