Indecomposable representations and oscillator realizations of the exceptional Lie algebra G_2

In this paper various representations of the exceptional Lie algebra G_2 are investigated in a purely algebraic manner, and multi-boson/multi-fermion realizations are obtained. Matrix elements of the master representation, which is defined on the space of the universal enveloping algebra of G_2, are explicitly determined. From this master representation, different indecomposable representations defined on invariant subspaces or quotient spaces with respect to these invariant subspaces are discussed. Especially, the elementary representations of G_2 are investigated in detail, and the corresponding six-boson realization is given. After obtaining explicit forms of all twelve extremal vectors of the elementary representation with the highest weight {\Lambda}, all representations with their respective highest weights related to {\Lambda} are systematically discussed. For one of these representations the corresponding five-boson realization is constructed. Moreover, a new three-fermion realization from the fundamental representation (0,1) of G_2 is constructed also.Comment: 29 pages, 4 figure

Improving the security of quantum direct communication with authentication

Two protocols of quantum direct communication with authentication [Phys. Rev. A {\bf 73}, 042305 (2006)] are recently proposed by Lee, Lim and Yang. In this paper we will show that in the two protocols the authenticator Trent should be prevented from knowing the secret message of communication. The first protocol can be eavesdropped by Trent using the the intercept-measure-resend attack, while the second protocol can be eavesdropped by Trent using single-qubit measurement. To fix these leaks, I revise the original versions of the protocols by using the Pauli-Z operation $\sigma_z$ instead of the original bit-flip operation $X$. As a consequence, the protocol securities are improved.Comment: Any suggestion,comment or help is welcome

Lanthanum exerts acute toxicity and histopathological changes in gill and liver tissue of rare minnow (Gobiocypris rarus)

We evaluated the acute toxicity effects of lanthanum (La(III)) on gill and liver of rare minnow (Gobiocypris rarus). The median lethal concentration of La (III) at 96 h was 1.92 mg L-1. Rare minnow were reared in freshwater and exposed to 0.04, 0.08, 0.16, 0.32 and 0.80 mg L-1 La (III) for 21 d. Gill and liver samples were analyzed by light microscopy. The main histopathological changes induced by La (III) in gills were epithelial lifting, filamentary epithelial proliferation,edema, lamellar fusion, desquamation, and necrosis. Histopathological changes induced by La (III) in the liver included dilation of sinusoids, focal congestion, pyknotic nuclei, karyohexis and karyolysis, vacuolar degeneration, and numerous necrosis areas. Hypsometric analysis indicated significant changes in the measures of gill dimensions (average length, width, area), suggesting metabolic disturbance (gas exchange) upon La (III) exposure. The result showed that La (III) severely affects fish gill and liver.</p

Environmental performance rating and disclosure - China's green-watch program

This paper describes a new incentive-based pollution control program in China in which the environmental performance of firms is rated and reported to the public. Firms are rated from best to worst using five colors-green, blue, yellow, red, and black-and the ratings are disseminated to the public through the media. The impact has been substantial, suggesting that public disclosure provides a significant incentive for firms to improve their environmental performance. The paper focuses on the experience of the first two disclosure programs, in Zhenjiang, Jiangsu Province and Hohhot, Inner Mongolia. Successful implementation of these programs at two very different levels of economic and institutional development suggests that public disclosure should be feasible in most of China. The Zhenjiang and Hohhot experiences have also shown that performance disclosure can significantly reduce pollution, even in settings where environmental nongovernmental organizations are not very active and there is no formal channel for public participation in environmental regulation.Environmental Economics&Policies,Public Health Promotion,Decentralization,Water and Industry,Health Monitoring&Evaluation,Environmental Economics&Policies,Water and Industry,Health Monitoring&Evaluation,National Governance,Health Economics&Finance