Critical temperature for the two-dimensional attractive Hubbard Model

The critical temperature for the attractive Hubbard model on a square lattice is determined from the analysis of two independent quantities, the helicity modulus, $\rho_s$, and the pairing correlation function, $P_s$. These quantities have been calculated through Quantum Monte Carlo simulations for lattices up to $18\times 18$, and for several densities, in the intermediate-coupling regime. Imposing the universal-jump condition for an accurately calculated $\rho_s$, together with thorough finite-size scaling analyses (in the spirit of the phenomenological renormalization group) of $P_s$, suggests that $T_c$ is considerably higher than hitherto assumed.Comment: 5 pages, 6 figures. Accepted for publication in Phys. Rev.

Changes of Several Psychological Measures in the Patients with Craniomandibular Disorders, Bruxing Behavior and Sexual Abuse History

Aim: The understanding of psychological correlates of Craniomandibular disorders and Bruxing Behavior has seen significant progress in the last few years. However, studies evaluating association between more complex psychological measures in such disorders are extremely scarce. To investigate this, we evaluated frequency of sexual abuse history in the experimental and two control groups and scores in depression, somatization and dissociation in those with Craniomandibular Disorders and Bruxism with/without sexual abuse history.Methods: Clinical examination, self-report, chief complaint, criteria for craniomandibular disorders and bruxism, the Becker-Lausen Questionnaire for sexual abuse were used in the Craniomandibular Disorder+ Bruxing Behavior, and in two control subgroups to gather data about sexual abuse history. The Beck Depression Inventory (BDI), 32 questions from the Screening Somatoform Disorders (SOMS-2) instrument and the Dissociative Experience Scale (DES) were used in the Craniomandibular Disorder + Bruxism + Sexual Abuse (n=39), in the Craniomandibular Disorder + Bruxism with no sexual abuse subgroup (n=158) and in the no Craniomandibular Disorders no Sexual Abuse subgroup (n=50) so as to gather data about depression, somatization and dissociation, respectively.Results: We show that there was no a statistically significant difference when comparing frequency of sexual abuse history in the experimental and in the two control groups. Means in depression were about 14.7; 11.4; and 9.3 in the Craniomandibular Disorder + Bruxism and Sexual abuse, in the Craniomandibular Disorder + Bruxism with no sexual abuse history, and in the no Craniomandibular Disorders no Sexual abuse history subgroups, respectively (Kruskall-Wallis statistics with post test p<0.02). Means in somatization were 12.1, 10.3, and 8.0, respectively in those subgroups (p<0.006). Means in dissociation were about 22.3, 15.6, and 15.2, respectively (p<0.007).Conclusions: Means in depression, somatization and dissociation were higher and significantly different in the Craniomandibular + bruxing behavior + sexual abuse history subgroup. This study provides further data on frequency of sexual abuse in craniomandibular disorder and bruxer subjects, expands current knowledge about depression and somatization and provides non previously reported data on dissociation

Quantum Monte Carlo study of the 3D attractive Hubbard model

We study the three-dimensional (3D) attractive Hubbard model by means of the Determinant Quantum Monte Carlo method. This model is a prototype for the description of the smooth crossover between BCS superconductivity and Bose-Einstein condensation. By detailed finite-size scaling we extract the finite-temperature phase diagram of the model. In particular, we interpret the observed behavior according to a scenario of two fundamental temperature scales; T* associated with Cooper pair formation and Tc with condensation (giving rise to long-range superconducting order). Our results also indicate the presence of a recently conjectured phase transition hidden by the superconducting state. A comparison with the 2D case is briefly discussed, given its relevance for the physics of high-Tc cuprate superconductors.Comment: 4 pages, 4 Postscript figure