Artificial graphene structures embedded in semiconductors could open novel routes for studies of electron interactions in 1ow-dimensional systems. We propose a way to manipulate the transport properties of massless Di...Artificial graphene structures embedded in semiconductors could open novel routes for studies of electron interactions in 1ow-dimensional systems. We propose a way to manipulate the transport properties of massless Dirac fermions in an artificial graphene-based tunnel junction. Velocity-modulation control of electron wave propagation in the different regions can be regarded as velocity barriers. Transmission probability of electron is affected profoundly by this velocity barrier. We find that there is no confinement for Dirac electron as the velocity ratio ζ is less than 1, but when the velocity ratio is larger than 1 the confined state appears in the continuum band. These localized Dirac electrons may lead to the decreasing of transmission probability.展开更多
This study examines the association between corporate governance mechanisms （i.e., internal corporate governance, ownership structure, and external corporate govemance） and stock investment risk （i.e., idiosyncrati...This study examines the association between corporate governance mechanisms （i.e., internal corporate governance, ownership structure, and external corporate govemance） and stock investment risk （i.e., idiosyncratic risk, systematic risk, and total risk of non-financial listed firms in Thailand in 2007）. The multiple regression analysis is employed to test the hypotheses, and the results suggest that firms with higher market power have lower systematic risk. It implies that firms with higher market power can reduce the unavoidable risk when compared with firms that have lower market power. Firms with more media coverage will have higher systematic risk, which indicates that firms which publish more news will have higher unavoidable risk. This research may be the first to provide the evidence of the association between corporate govemance mechanisms and stock investment risk. Interestingly still, this study has utilized the data of Thailand, which is an emerging market economy with a capital market structure different from those of the developed market economies, and the results of this study are anticipated to be applicable to other similar studies in other emerging market economies.展开更多
This paper generalizes a method of generating shift sequences in the interleaved construction proposed by Gong.With the new shift sequences,some new families of p-ary sequences with desired properties can be obtained....This paper generalizes a method of generating shift sequences in the interleaved construction proposed by Gong.With the new shift sequences,some new families of p-ary sequences with desired properties can be obtained.A lower bound on the number of new families of binary sequences is also established.展开更多
基金Supported by the National Natural Science Foundation of China under Grants Nos.10174024 and 10474025
文摘Artificial graphene structures embedded in semiconductors could open novel routes for studies of electron interactions in 1ow-dimensional systems. We propose a way to manipulate the transport properties of massless Dirac fermions in an artificial graphene-based tunnel junction. Velocity-modulation control of electron wave propagation in the different regions can be regarded as velocity barriers. Transmission probability of electron is affected profoundly by this velocity barrier. We find that there is no confinement for Dirac electron as the velocity ratio ζ is less than 1, but when the velocity ratio is larger than 1 the confined state appears in the continuum band. These localized Dirac electrons may lead to the decreasing of transmission probability.
文摘This study examines the association between corporate governance mechanisms （i.e., internal corporate governance, ownership structure, and external corporate govemance） and stock investment risk （i.e., idiosyncratic risk, systematic risk, and total risk of non-financial listed firms in Thailand in 2007）. The multiple regression analysis is employed to test the hypotheses, and the results suggest that firms with higher market power have lower systematic risk. It implies that firms with higher market power can reduce the unavoidable risk when compared with firms that have lower market power. Firms with more media coverage will have higher systematic risk, which indicates that firms which publish more news will have higher unavoidable risk. This research may be the first to provide the evidence of the association between corporate govemance mechanisms and stock investment risk. Interestingly still, this study has utilized the data of Thailand, which is an emerging market economy with a capital market structure different from those of the developed market economies, and the results of this study are anticipated to be applicable to other similar studies in other emerging market economies.
基金supported by the National Natural Science Foundation of China under Grant No.61170257supported by the National Key Basic Research Program of China under Grant No.2013CB834203+1 种基金the National Science Foundation of China under Grant Nos.10990011 and 61070172the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No.XDA06010702
文摘This paper generalizes a method of generating shift sequences in the interleaved construction proposed by Gong.With the new shift sequences,some new families of p-ary sequences with desired properties can be obtained.A lower bound on the number of new families of binary sequences is also established.
