Exact Results of Strongly Correlated Systems at Finite Temperature

Some rigorous conclusions of the Hubbard model, Kondo lattice model and periodic Anderson model at finite temperature are acquired employing the fluctuation-dissipation theorem and particle-hole transform. The main conclusion states that for the three models, the expectation value of ${\bf \tilde{S}}^2-{\bf \tilde{S}}^2_z$ will be of order $N_{\Lambda}$ at any finite temperature.Comment: 8 pages, no figures, LATEX, corrected some typos, to appear in Phys. Lett.

Research on Corrective Feedback in ESL/EFL Classrooms

Corrective feedback (CF) has been one research focus in Second Language Acquisition in recent years, the study of which helps second language learners to acquire the target language successfully. The paper is to present an overview of studies on CF in ESL/EFL classroom interaction from 2000 to 2015. Firstly, the conceptual issues of CF are analyzed, including its definition, process, and category. Secondly, theoretical development of CF is reviewed which can be divided into three stages. Thirdly, research content on CF is introduced from Chinese and foreign scholars. Finally, the author makes an overall conclusion in which problems in current studies are pointed and future development of CF research is discussed at the end of the paper