Calanus sinicus is a calanoid copepod widely distributed in coastal waters of China and Japan, and oversummering strategies may have major impacts on their population dynamics which in turn affect local marine food we...Calanus sinicus is a calanoid copepod widely distributed in coastal waters of China and Japan, and oversummering strategies may have major impacts on their population dynamics which in turn affect local marine food web structure. The abundance, stage composition, and sex composition of the planktonic copepod C. sinicus were studied from August to October 2002 in the southern Yellow Sea to understand how its population recovers from the over-summering state. Results showed that C. sinicus had low reproduction in August due to high temperature, except in waters near the Cheju Island with rich food and moderate bottom temperature, but the reproduction rates here decreased in September–October as food availability declined. When temperature dropped in September–October, C. sinicus actively propagated in coastal shallow waters. However, reproduction rates of C. sinicus individuals inhabiting the Yellow Sea Cold Water Mass(YSCWM) remained low during the three months of the study. The percentage of C. sinicus females was high during the reproductive period, which suggests that the sex composition of adult C. sinicus may reflect whether or not the population is in the reproductive mode.Numerous fifth copepodite stage(CV) C. sinicus aggregated in the YSCWM in a suspended developmental stage during the three months of this study, and they potentially served as the parental individuals for population development when conditions became optimal for reproduction later in the year.展开更多
Androgens have potent anabolic effects on skeletal muscle and decline with age in parallel to losses in muscle mass and strength. This loss of muscle mass and function, known as sarcopenia, is the central event in dev...Androgens have potent anabolic effects on skeletal muscle and decline with age in parallel to losses in muscle mass and strength. This loss of muscle mass and function, known as sarcopenia, is the central event in development of frailty, the vulnerable health status that presages adverse outcomes and rapid functional decline in older adults. The potential role of falling androgen levels in the development of frailty and their utility as function promoting therapies in older men has therefore attracted considerable attention. This review summarizes current concepts and definitions in muscle ageing, sarcopenia and frailty, and evaluates recent developments in the study of androgens and frailty. Current evidence from observational and interventional studies strongly supports an effect of androgens on muscle mass in ageing men, but effects on muscle strength and particularly physical function have been less clear. Androgen treatment has been generally well-tolerated in studies of older men, but concerns remain over higher dose treatments and use in populations with high cardiovascular risk. The first trials of selective androgen receptor modulators （SARMs） suggest similar effects on muscle mass and function to traditional androgen therapies in older adults. Important future directions include the use of these agents in combination with exercise training to promote functional ability across different populations of older adults, as well as more focus on the relationships between concurrent changes in hormone levels, body composition and physical function in observational studies.展开更多
China currently has the world's most skewed national sex ratio at birth.In this paper,we use data from China's 2001 National Family Planning and Reproductive Health Survey and employ hierarchical logistic mode...China currently has the world's most skewed national sex ratio at birth.In this paper,we use data from China's 2001 National Family Planning and Reproductive Health Survey and employ hierarchical logistic models to study how macro factors(mainly fertility policy and economic indicators,as represented by per capita GDP of the village units sampled in this research)and micro factors(mainly fertility intention and sex composition of children)affect the gender of the next birth.We find that the effect of fertility policies is intertwined with the sex composition of children already born.For those couples who have had a son(or sons),fertility policy exerts no effect;but for those with only daughters,the effect is significant.Furthermore,fertility intention,independent from fertility policy,has a significant effect on the gender of the next birth.展开更多
基金The NSFC-Shandong Joint Fund for Marine Ecology and Environmental Sciences under contract No.U1606404the National Natural Science Foundation of China under contract No.41230963+1 种基金the National Basic Research Program(973 program)of China under contract Nos 2011CB403604 and G1999043708the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA11020305
文摘Calanus sinicus is a calanoid copepod widely distributed in coastal waters of China and Japan, and oversummering strategies may have major impacts on their population dynamics which in turn affect local marine food web structure. The abundance, stage composition, and sex composition of the planktonic copepod C. sinicus were studied from August to October 2002 in the southern Yellow Sea to understand how its population recovers from the over-summering state. Results showed that C. sinicus had low reproduction in August due to high temperature, except in waters near the Cheju Island with rich food and moderate bottom temperature, but the reproduction rates here decreased in September–October as food availability declined. When temperature dropped in September–October, C. sinicus actively propagated in coastal shallow waters. However, reproduction rates of C. sinicus individuals inhabiting the Yellow Sea Cold Water Mass(YSCWM) remained low during the three months of the study. The percentage of C. sinicus females was high during the reproductive period, which suggests that the sex composition of adult C. sinicus may reflect whether or not the population is in the reproductive mode.Numerous fifth copepodite stage(CV) C. sinicus aggregated in the YSCWM in a suspended developmental stage during the three months of this study, and they potentially served as the parental individuals for population development when conditions became optimal for reproduction later in the year.
文摘Androgens have potent anabolic effects on skeletal muscle and decline with age in parallel to losses in muscle mass and strength. This loss of muscle mass and function, known as sarcopenia, is the central event in development of frailty, the vulnerable health status that presages adverse outcomes and rapid functional decline in older adults. The potential role of falling androgen levels in the development of frailty and their utility as function promoting therapies in older men has therefore attracted considerable attention. This review summarizes current concepts and definitions in muscle ageing, sarcopenia and frailty, and evaluates recent developments in the study of androgens and frailty. Current evidence from observational and interventional studies strongly supports an effect of androgens on muscle mass in ageing men, but effects on muscle strength and particularly physical function have been less clear. Androgen treatment has been generally well-tolerated in studies of older men, but concerns remain over higher dose treatments and use in populations with high cardiovascular risk. The first trials of selective androgen receptor modulators （SARMs） suggest similar effects on muscle mass and function to traditional androgen therapies in older adults. Important future directions include the use of these agents in combination with exercise training to promote functional ability across different populations of older adults, as well as more focus on the relationships between concurrent changes in hormone levels, body composition and physical function in observational studies.
基金supported by the key project of the National Social Science Foundation of China(14AZD096).
文摘China currently has the world's most skewed national sex ratio at birth.In this paper,we use data from China's 2001 National Family Planning and Reproductive Health Survey and employ hierarchical logistic models to study how macro factors(mainly fertility policy and economic indicators,as represented by per capita GDP of the village units sampled in this research)and micro factors(mainly fertility intention and sex composition of children)affect the gender of the next birth.We find that the effect of fertility policies is intertwined with the sex composition of children already born.For those couples who have had a son(or sons),fertility policy exerts no effect;but for those with only daughters,the effect is significant.Furthermore,fertility intention,independent from fertility policy,has a significant effect on the gender of the next birth.
