Phase diagram of the extended Hubbard chain with charge-dipole interactions

We consider a modified extended Hubbard model (EHM) which, in addition to the on-site repulsion U and nearest-neighbor repulsion V, includes polarization effects in second-order perturbation theory. The model is equivalent to an EHM with renormalized U plus a next-nearest-neighbor repulsion term. Using a method based on topological quantum numbers (charge and spin Berry phases), we generalize to finite hopping t the quantum phase diagram in one dimension constructed by van den Brink et al. (Phys. Rev. Lett. 75, 4658 (1995)). At hopping t=0 there are two charge density-wave phases, one spin density-wave phase and one intermediate phase with charge and spin ordering, depending on the parameter values. At t \neq 0 the nature of each phase is confirmed by studying correlation functions. However, in addition to the strong-coupling phases, a small region with bond ordering appears. The region occupied by the intermediate phase first increases and then decreases with increasing t, until it finally disappears for t of the order but larger than U. For small t, the topological transitions agree with the results of second order perturbation theory.Comment: 6 pages, 5 figures, two columns latex version. Accepted for publication in Physical Review B. Mistaken reference 16 has been correcte

GPS' attitudes towards digital technologies for depression: An online survey in primary care

Background Digital or electronic mental health (e-mental health) interventions can be useful approaches in reducing the burden of depression, with tools available for use in prevention, treatment, or relapse prevention. They may have specific benefit for primary care, as depression is often managed in this setting. However, little is known about attitudes and barriers among GPS towards e-mental health interventions for depression. Aim This study aimed to assess attitudes, knowledge, use, and barriers for depressionfocused e-mental health among GPS across the UK. Design and setting An online survey of self-selecting GPS in the UK conducted over a 10-day period in December 2017. Method The survey consisted of 13 multiple choice questions posted on the Doctors.net.UK (DNUK) website. Results In all, 1044 responses were included; 72% of GPS reported using at least one type of e-mental health intervention for depression. Overall, GPS reported that e-mental health interventions are most effective when delivered in a guided way, rather than in an unguided manner. In addition, 92% of GPS reported that neither they nor their colleagues received e-mental health training. Conclusion A moderate number of GPS use e-mental health for depression in their services, and report it is likely that its use will increase. There is a gap in training and awareness of effective interventions. GPS consider guided e-mental health interventions to be most effective, in contrast to the unguided way it is mostly offered in primary care

Phenotypic consequences of the GJD2 risk genotype in myopia development

PURPOSE. To study the relatively high effect of the refractive error gene GJD2 in human myopia, and to assess its relationship with refractive error, ocular biometry and lifestyle in various age groups. METHODS. The population-based Rotterdam Study (RS), high myopia case-control study MYopia STudy, and the birth-cohort study Generation R were included in this study. Spherical equivalent (SER), axial length (AL), axial length/corneal radius (AL/CR), vitreous depth (VD), and anterior chamber depth (ACD) were measured using standard ophthalmologic procedures. Biometric measurements were compared between GJD2 (rs524952) genotype groups; education and environmental risk score (ERS) were calculated to estimate gene-environment interaction effects, using the Synergy index (SI). RESULTS. RS adults carrying two risk alleles had a lower SER and longer AL, ACD and VD (AA versus TT, 0.23D vs. 0.70D; 23.79 mm vs. 23.52 mm; 2.72 mm vs. 2.65 mm; 16.12 mm vs. 15.87 mm; all P &lt; 0.001). Children carrying two risk alleles had larger AL/CR at ages 6 and 9 years (2.88 vs. 2.87 and 3.00 vs. 2.96; all P &lt; 0.001). Education and ERS both negatively influenced myopia and the biometric outcomes, but gene-environment interactions did not reach statistical significance (SI 1.25 [95% confidence interval {CI}, 0.85–1.85] and 1.17 [95% CI, 0.55–2.50] in adults and children). CONCLUSIONS. The elongation of the eye caused by the GJD2 risk genotype follows a dose-response pattern already visible at the age of 6 years. These early effects are an example of how a common myopia gene may drive myopia.</p

Study of the in-plane and c-axis fluctuation conductivity of melt-textured YBa 2Cu 3O 7 under hydrostatic pressure

We have experimentally studied the pressure dependence of the fluctuation conductivity in melt-processed YBa2Cu3O7 (YBCO) for currents applied parallel or perpendicular to the Cu-O2 atomic layers. Results show that the asymptotic critical regime is described by the 3D-XY universality class for both in-plane and off-plane conductivity components. The dynamical exponent for the in-plane conductivity component is z = 1.5, independently of the applied pressure. However, a pressure induced crossover in the dynamical universality class is observed in the c-axis fluctuation conductivity, where the exponent changes gradually from z = 1.5 to z = 2. The Ginzburg number increases with pressure for both crystalline orientations. This behavior suggests that the in-plane and c-axis components of the G-L coherence length decrease upon pressure application. The fluctuation spectrum for the Gaussian regime in the planar conductivity keeps the three dimensional character. However, filamentary fluctuations are observed along the c-axis above the Ginzburg temperature. Our results for the out-of-plane fluctuation conductivity in YBCO suggest that the c-axis transport is predominantly coherent in this system