In order to determine whether growth performance could be improved by hybridizing full-sib families of Manila clam （Ruditapes philippinarum）, crosses between two full-sib families including self and reciprocal cross...In order to determine whether growth performance could be improved by hybridizing full-sib families of Manila clam （Ruditapes philippinarum）, crosses between two full-sib families including self and reciprocal crosses were carried out. The effects of heterosis, combining ability and interaction on the growth of shell length were estimated. The results showed that the growth of hybrid larvae was intermediate between parents on days 6 and 9. Heterosis on shell length was observed, which varied at juvenile stage. The cross of ♂A×♀B （Hp varied between 10.41% and 68.27%） displayed larger heterosis than ♂A×♀B （Hp varied between 1.89% and 32.33%） did, suggesting that ♂A×♀B was an ideal hatchery method of improving the growth performance of Manila clam. The variances of general combining ability （GCA）, special combining ability （SCA） and interaction （I） were significant in shell length （P〈 0.05）, indicating that both additive and non-additive genetic factors were important contributors to the growth of larvae and juveniles. The GCA for shell length of ♂A×♀B was higher than that of ♂A×♀B at both larval and juvenile stages. This con- firmed that the cross between ♂A and ♀B showed great growth in shell length. In summary, the growth of Manila clam seeds could be improved by hybridizing selected parents from large numbers of full-sib families.展开更多
Much has been written and researched about transformational change and the exogenous events that result in radical institutional transformation （Di Maggio ＆ Powell, 1983; Hannan＆ Freeman, 1989; Fligstein, 1996; Zor...Much has been written and researched about transformational change and the exogenous events that result in radical institutional transformation （Di Maggio ＆ Powell, 1983; Hannan＆ Freeman, 1989; Fligstein, 1996; Zorn, Dobbin, ＆ Kwok, 2006）. Accounts are provided of external agents disturbing the existing stasis of the institution and transforming the institution into something else that reflect a new paradigm or set of interests. Often, what is neglected in these accounts is what fractures exist in the original institution that would make them vulnerable and allow penetration by exogenous influences. Mahoney and Thelen （20 l 0） went beyond a general model of change that described the collapse of one set of institutional norms to be replaced by another. The model of change they propose takes into account both exogenous as well as endogenous factors as being the source of institutional change. They went on to state a view that transformation change as being a result of abrupt, wholesale breakdown needs to be rethought to include incremental, endogenous shifts in thinking that can often result in fundamental transformations.展开更多
Srivastava and Jhajj [ 1 6] proposed a class of estimators for estimating population variance using multi auxiliary variables in simple random sampling and they utilized the means and variances of auxiliary variables....Srivastava and Jhajj [ 1 6] proposed a class of estimators for estimating population variance using multi auxiliary variables in simple random sampling and they utilized the means and variances of auxiliary variables. In this paper, we adapted this class and motivated by Searle [13], and we suggested more generalized class of estimators for estimating the population variance in simple random sampling. The expressions for the mean square error of proposed class have been derived in general form. Besides obtaining the minimized MSE of the proposed and adapted class, it is shown that the adapted classis the special case of the proposed class. Moreover, these theoretical findings are supported by an empirical study of original data.展开更多
基金supported by the earmarked fund for Modern Agro-industry Technology Research System (CARS-48)grants from the ‘863’ Project of China (2012AA10AA400)
文摘In order to determine whether growth performance could be improved by hybridizing full-sib families of Manila clam （Ruditapes philippinarum）, crosses between two full-sib families including self and reciprocal crosses were carried out. The effects of heterosis, combining ability and interaction on the growth of shell length were estimated. The results showed that the growth of hybrid larvae was intermediate between parents on days 6 and 9. Heterosis on shell length was observed, which varied at juvenile stage. The cross of ♂A×♀B （Hp varied between 10.41% and 68.27%） displayed larger heterosis than ♂A×♀B （Hp varied between 1.89% and 32.33%） did, suggesting that ♂A×♀B was an ideal hatchery method of improving the growth performance of Manila clam. The variances of general combining ability （GCA）, special combining ability （SCA） and interaction （I） were significant in shell length （P〈 0.05）, indicating that both additive and non-additive genetic factors were important contributors to the growth of larvae and juveniles. The GCA for shell length of ♂A×♀B was higher than that of ♂A×♀B at both larval and juvenile stages. This con- firmed that the cross between ♂A and ♀B showed great growth in shell length. In summary, the growth of Manila clam seeds could be improved by hybridizing selected parents from large numbers of full-sib families.
文摘Much has been written and researched about transformational change and the exogenous events that result in radical institutional transformation （Di Maggio ＆ Powell, 1983; Hannan＆ Freeman, 1989; Fligstein, 1996; Zorn, Dobbin, ＆ Kwok, 2006）. Accounts are provided of external agents disturbing the existing stasis of the institution and transforming the institution into something else that reflect a new paradigm or set of interests. Often, what is neglected in these accounts is what fractures exist in the original institution that would make them vulnerable and allow penetration by exogenous influences. Mahoney and Thelen （20 l 0） went beyond a general model of change that described the collapse of one set of institutional norms to be replaced by another. The model of change they propose takes into account both exogenous as well as endogenous factors as being the source of institutional change. They went on to state a view that transformation change as being a result of abrupt, wholesale breakdown needs to be rethought to include incremental, endogenous shifts in thinking that can often result in fundamental transformations.
文摘Srivastava and Jhajj [ 1 6] proposed a class of estimators for estimating population variance using multi auxiliary variables in simple random sampling and they utilized the means and variances of auxiliary variables. In this paper, we adapted this class and motivated by Searle [13], and we suggested more generalized class of estimators for estimating the population variance in simple random sampling. The expressions for the mean square error of proposed class have been derived in general form. Besides obtaining the minimized MSE of the proposed and adapted class, it is shown that the adapted classis the special case of the proposed class. Moreover, these theoretical findings are supported by an empirical study of original data.
