The chromosome theory of inheritance was established during the three first decades of the 20th century. During the early stage of its substantiating, there were lots of puzzles and little evidence that could validate...The chromosome theory of inheritance was established during the three first decades of the 20th century. During the early stage of its substantiating, there were lots of puzzles and little evidence that could validate it. The cytological processes were obscure and several scientists maintained serious doubts concerning the existence of a connection between Mendel＇s principles and the behaviour of chromosomes during cell division. It was vital to associate an external, observable characteristic of the organism to a specific chromosome, and this was achieved when sex was connected to special chromosomes. At that time, however, some important scholars refused to accept or delayed acceptance of the conception that the hereditary factors （later called genes） were physical entities located along the chromosomes. Such was the case of Thomas Morgan （1866-1945） and William Bateson （186 I- 1926）. Their attitudes could be explained by considering the doubtful ground of the hypothesis at that time. It is more difficult, however, to understand the attitude of Edmund Beecher Wilson （1856-1939）. Being an expert in cytology he was acquainted with all the difficulties concerning the chromosome hypothesis. Nonetheless, from 1905 onward, he attributed little weight to the problems and dedicated a notable effort to obtaining evidence that could have grounded it. This paper analyses Wilson＇s attitude focusing on his studies from 1900 to 1915 and the scientific context of this period. This study led to the conclusion that Wilson＇s attitude could be explained in methodological terms by the adoption of an instrumentalist attitude, while Bateson and Morgan adopted a realistic perspective.展开更多
The concept of derivations and generalized inner derivations has been generalized as an additive function δ： R → R satisfying δ （xy） = δ（x）y＋xd（y） for all x, y ∈ R, where d is a derivation on R. Such a fu...The concept of derivations and generalized inner derivations has been generalized as an additive function δ： R → R satisfying δ （xy） = δ（x）y＋xd（y） for all x, y ∈ R, where d is a derivation on R. Such a function δ is called a generalized derivation. Suppose that U is a Lie ideal of R such that u^2 ∈ U for all u ∈ U. In this paper, we prove that U lahtain in Z（R） when one of the following holds： （1） δ（[u, v]） = u o v =（2） δ（[u,v]）=[u o v] = 0 （3） δ（u o v） = [u, v] （4） δ（u o v）＋δ[u, v] = 0 for all u, v ∈ U.展开更多
In the framework of the NRQCD factorization formalism,we calculate the decay rate for the process Υ(1 S) → ccgg to the next-to-leading order(NLO) in the relative velocity v of the b quark in the bottomonium rest fra...In the framework of the NRQCD factorization formalism,we calculate the decay rate for the process Υ(1 S) → ccgg to the next-to-leading order(NLO) in the relative velocity v of the b quark in the bottomonium rest frame.We also study the momentum distributions of the charm quark and the charmed-hadron in the decay.The momentum distribution of the charmed-hadron is obtained by convolving the charm quark momentum distribution with a fragmentation function of the charm quark into the hadron.In addition,we fit the nonperturbative NRQCD matrix element v 2 Υ through comparing the theoretical prediction with the measurement from the BaBar collaboration for the decay rate of Υ(1 S) → D + X.In return,taking this matrix element as an input parameter,we predict the decay rates as well as the momentum distributions for a collection of charmed-hadrons in the process Υ(1S) → ccgg → hX.展开更多
文摘The chromosome theory of inheritance was established during the three first decades of the 20th century. During the early stage of its substantiating, there were lots of puzzles and little evidence that could validate it. The cytological processes were obscure and several scientists maintained serious doubts concerning the existence of a connection between Mendel＇s principles and the behaviour of chromosomes during cell division. It was vital to associate an external, observable characteristic of the organism to a specific chromosome, and this was achieved when sex was connected to special chromosomes. At that time, however, some important scholars refused to accept or delayed acceptance of the conception that the hereditary factors （later called genes） were physical entities located along the chromosomes. Such was the case of Thomas Morgan （1866-1945） and William Bateson （186 I- 1926）. Their attitudes could be explained by considering the doubtful ground of the hypothesis at that time. It is more difficult, however, to understand the attitude of Edmund Beecher Wilson （1856-1939）. Being an expert in cytology he was acquainted with all the difficulties concerning the chromosome hypothesis. Nonetheless, from 1905 onward, he attributed little weight to the problems and dedicated a notable effort to obtaining evidence that could have grounded it. This paper analyses Wilson＇s attitude focusing on his studies from 1900 to 1915 and the scientific context of this period. This study led to the conclusion that Wilson＇s attitude could be explained in methodological terms by the adoption of an instrumentalist attitude, while Bateson and Morgan adopted a realistic perspective.
文摘The concept of derivations and generalized inner derivations has been generalized as an additive function δ： R → R satisfying δ （xy） = δ（x）y＋xd（y） for all x, y ∈ R, where d is a derivation on R. Such a function δ is called a generalized derivation. Suppose that U is a Lie ideal of R such that u^2 ∈ U for all u ∈ U. In this paper, we prove that U lahtain in Z（R） when one of the following holds： （1） δ（[u, v]） = u o v =（2） δ（[u,v]）=[u o v] = 0 （3） δ（u o v） = [u, v] （4） δ（u o v）＋δ[u, v] = 0 for all u, v ∈ U.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10875130,10935012,and 10875156
文摘In the framework of the NRQCD factorization formalism,we calculate the decay rate for the process Υ(1 S) → ccgg to the next-to-leading order(NLO) in the relative velocity v of the b quark in the bottomonium rest frame.We also study the momentum distributions of the charm quark and the charmed-hadron in the decay.The momentum distribution of the charmed-hadron is obtained by convolving the charm quark momentum distribution with a fragmentation function of the charm quark into the hadron.In addition,we fit the nonperturbative NRQCD matrix element v 2 Υ through comparing the theoretical prediction with the measurement from the BaBar collaboration for the decay rate of Υ(1 S) → D + X.In return,taking this matrix element as an input parameter,we predict the decay rates as well as the momentum distributions for a collection of charmed-hadrons in the process Υ(1S) → ccgg → hX.
