A general graded reflection equation algebra is proposed and the corresponding boundary quantum inverse scattering method is formulated. The formalism is applicable to all boundary lattice systems where an invertible R-matrix exists. As an application, the integrable open-boundary conditions for the q-deformed supersymmetric U model of strongly correlated electrons are investigated. The diagonal boundary K-matrices are found and a class of integrable boundary terms are determined. The boundary system is solved by means of the coordinate space Bethe ansatz technique and the Bethe ansatz equations are derived. As a sideline, it is shown that all R-matrices associated with a quantum affine superalgebra enjoy the crossing-unitarity property.

Integrable Kondo impurities in two cases of the one-dimensional t − J model are studied by means of the boundary Z2-graded quantum inverse scattering method. The boundary K matrices depending on the local magnetic moments of the impurities are presented as nontrivial realizations of the reflection equation algebras in an impurity Hilbert space. Furthermore, these models are solved by using the algebraic Bethe ansatz method and the Bethe ansatz equations are obtained.

This paper aims to reveal the nexus for sulfur dioxide (SO 2 ) emission and income, as well as the effects of technical progress on SO 2 emission in China based on environment Kuznets curve (EKC) hypothesis. The spatial panel technique is used in case the coefficient estimates are biased due to the negligence of spatial dependence. With the provincial panel data of China from 2004 to 2014, this is the first research that finds an inverse N-trajectory of the relationship between SO 2 emission and economic growth and confirms the beneficial impacts of technical advancement on SO 2 emission abatement. The empirical results also suggest that the industrial structure change is an important driving force of the SO 2 EKC. In addition, the direct and spillover effects of determinants on sulfur emission are clarified and estimated by a correct approach. Finally, we check the stability of our conclusions on the EKC shape for SO 2 and technical progress effects when controlling for different variables and specifications, through which we find the turning points are sensitive to variables selections.

Is nitrogen oxides emissions spatially correlated in a Chinese context? What is the relationship between nitrogen oxides emission levels and fast-growing economy/urbanization? More importantly, what environmental preservation and economic developing policies should China’s central and local governments take to mitigate the overall nitrogen oxides emissions and prevent severe air pollution at the provincial level in specific locations and their neighboring areas? The present study aims to tackle these issues. This is the first research that simultaneously studies the nexus between nitrogen oxides emissions and economic development/urbanization, with the application of a spatial panel data technique. Our empirical findings suggest that spatial dependence of nitrogen oxides emissions distribution exists at the provincial level. Through the investigation of the existence of an environmental Kuznets curve (EKC) embedded within the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) framework, we conclude something interesting: an inverse N-shaped EKC describes both the income-nitrogen oxides nexus and the urbanization-nitrogen oxides nexus. Some well-directed policy advice is provided to reduce nitrogen oxides in the future. Moreover, these results contribute to the literature on development and pollution.

Integrable open-boundary condition for the q-deformed Essler-Korepin-Schoutens extended Hubbard model of strongly correlated electrons are studied in the framework of the boundary quantum inverse scattering method. Diagonal boundary K-matrices are found and nine classes of integrable boundary terms are determined. PACS Number(s): 71.20.Fd, 75.10.Jm, 75.10.LpOne-dimensional strongly correlated electron systems with boundaries are of great importance because of their promising role in theoretical condensed matter physics and possibly in high-T c superconductivity. 1 Boundary conditions and nontrivial boundary interactions for such systems, which are compatible with integrability in the bulk, are constructed from solutions of the graded reflection equations, 2 and have attracted much attention recently in connection with physical problems like X-ray edge singularities, 3 orthogonalities catastrophy 4 and tunneling through constrictions 5 in quantum wires. In particular, open boundaries and boundary fields for the Hubbard-like models 6-9 and for the supersymmetric t-J model 10-12 have been studied in connection with this. The results of the present paper may well have interesting applications to these problems.In this paper, we shall construct the open-boundary conditions for the q-deformed Essler-Korepin-Schoutens extended Hubbard model (EKS model) 1 which preserve the integrability of the model. This is achieved by solving the graded reflection equations for the diagonal boundary K-matrices.Let c j,σ and c † j,σ denote fermionic creation and annihilation operators for spin σ at site j, which satisfy the anti-commutation relations {c † i,σ , c j,τ } = δ ij δ στ , where i, j = 1, 2, . . . , L and σ, τ = ↑, ↓. We consider the open-boundary q-deformed EKS * 499 Mod. Phys. Lett. B 1999.13:499-507. Downloaded from www.worldscientific.com by UNIVERSITY OF CALIFORNIA @ SAN DIEGO on 03/14/15. For personal use only.