Difficulty in the Fermi-Liquid-Based Theory for the In-Plane Magnetic Anisotropy in Untwinned High-T_c Superconductor

Recently, Eremin and Manske [1] presented a oneband Fermi-liquid theory for the in-plane magnetic anisotropy in untwinned high-Tc superconductor YBa2Cu3O6:85 (YBCO). They claimed that they found good agreement with inelastic neutron scattering (INS) spectra. In this Comment, we point out that their conclusion on this important problem may be questionable due to an error in logic about the orthorhombicity delta_0 characterizing the lattice structure of YBCO. In Ref. [1], a single band at delta_0>0 is proved to be in accordance with the angle resolved photoemission spectroscopy (ARPES) on untwinned YBCO. But in their Erratum in PRL[3], they admit that delta_0= -0.03 was used to fit the INS data. Hence publications [1,3] contain errors that we believe invalidate their approach.Comment: This is a Comment on the paper of I. Eremin, and D. Manske, Phys. Rev. Lett. 94, 067006(2005

Community attachment in rural Iowa: multilevel test of a theoretical model with intervening variables

Previous systemic models of community attachment have not included individual participation in local community groups and attitudes toward the community as intervening variables to predict community attachment through individual sociodemographic characteristics. Social Identity Theory provides a perspective to justify their inclusion when community attachment is perceived as an outcome of individuals\u27 social identification with their own communities;Based on social identity theory, a systemic model is proposed to test the notion that community attachment indicated by its psychological dimension is affected significantly by individual participation in local community groups and attitudes toward the community which are predicted by individual differences in age, length of residence, education, and income. Path analysis and Hierarchical Linear Modeling were used to examine the specified relationships among the variables both at the individual-level and at the community-level. The results confirm that participation in local communities and attitudes toward the community are the primary determinants of psychological attachment to the community at the two levels. Significant community-level variations on some of the variable relations are also detected in hierarchical linear analysis. Two community characteristics, community social environment and the quality of community services, were studied as important structural factors to explain the observed community variations. The theoretical and empirical implications of the study were discussed to suggest future research issues and strategies for community integration efforts