Polaron formation for a non-local electron-phonon coupling: A variational wave-function study

We introduce a variational wave-function to study the polaron formation when the electronic transfer integral depends on the relative displacement between nearest-neighbor sites giving rise to a non-local electron-phonon coupling with optical phonon modes. We analyze the ground state properties such as the energy, the electron-lattice correlation function, the phonon number and the spectral weight. Variational results are found in good agreement with analytic weak-coupling perturbative calculations and exact numerical diagonalization of small clusters. We determine the polaronic phase diagram and we find that the tendency towards strong localization is hindered from the pathological sign change of the effective next-nearest-neighbor hopping.Comment: 11 page

Electron-phonon effects and transport in carbon nanotubes

We calculate the electron-phonon scattering and binding in semiconducting carbon nanotubes, within a tight binding model. The mobility is derived using a multi-band Boltzmann treatment. At high fields, the dominant scattering is inter-band scattering by LO phonons corresponding to the corners K of the graphene Brillouin zone. The drift velocity saturates at approximately half the graphene Fermi velocity. The calculated mobility as a function of temperature, electric field, and nanotube chirality are well reproduced by a simple interpolation formula. Polaronic binding give a band-gap renormalization of ~70 meV, an order of magnitude larger than expected. Coherence lengths can be quite long but are strongly energy dependent.Comment: 5 pages and 4 figure

Effects of an electronic topological transition for anisotropic low-dimensional superconductors

We study the superconducting properties of a two-dimensional superconductor in the proximity to an electronic topological transition (ETT). In contrast to the 3D case, we find that the superconducting gap at T=0, the critical temperature Tc, and the impurity scattering rate are characterized by a nonmonotonic behavior, with maxima occurring close to the ETT. We derive analytical expressions for the value of such maxima both in the s-wave and in the d-wave case. Such expressions are in good qualitative agreement with the phenomenological trend recently observed for Tc^max as a function of the hopping ratio t'/t across several cuprate compounds. We further analyze the effect of an ETT on the Ginzburg-Landau stiffness eta. Instead of vanishing at the ETT, as could be expected, thus giving rise to an increase of the fluctuation effects, in the case of momentum-independent electron-electron interaction, we find eta different from 0, as a result of an integration over the whole Fermi surface.Comment: to be published in Phys. Rev.

Social cognition in people with schizophrenia: A cluster-analytic approach

Background The study aimed to subtype patients with schizophrenia on the basis of social cognition (SC), and to identify cut-offs that best discriminate among subtypes in 809 out-patients recruited in the context of the Italian Network for Research on Psychoses. Method A two-step cluster analysis of The Awareness of Social Inference Test (TASIT), the Facial Emotion Identification Test and Mayer-Salovey-Caruso Emotional Intelligence Test scores was performed. Classification and regression tree analysis was used to identify the cut-offs of variables that best discriminated among clusters. Results We identified three clusters, characterized by unimpaired (42%), impaired (50.4%) and very impaired (7.5%) SC. Three theory-of-mind domains were more important for the cluster definition as compared with emotion perception and emotional intelligence. Patients more able to understand simple sarcasm (14 for TASIT-SS) were very likely to belong to the unimpaired SC cluster. Compared with patients in the impaired SC cluster, those in the very impaired SC cluster performed significantly worse in lie scenes (TASIT-LI <10), but not in simple sarcasm. Moreover, functioning, neurocognition, disorganization and SC had a linear relationship across the three clusters, while positive symptoms were significantly lower in patients with unimpaired SC as compared with patients with impaired and very impaired SC. On the other hand, negative symptoms were highest in patients with impaired levels of SC. Conclusions If replicated, the identification of such subtypes in clinical practice may help in tailoring rehabilitation efforts to the person's strengths to gain more benefit to the person

Novel Supreme Drug-Eluting Stents With Early Synchronized Antiproliferative Drug Delivery to Inhibit Smooth Muscle Cell Proliferation After Drug-Eluting Stents Implantation in Coronary Artery Disease Results of the PIONEER III Randomized Clinical Trial

BACKGROUND: Accelerated endothelial healing after targeted antiproliferative drug delivery may limit the long-term inflammatory response of drug-eluting stents (DESs). The novel Supreme DES is designed to synchronize early drug delivery within 4 to 6 weeks of implantation, leaving behind a prohealing permanent base layer. Whether the Supreme DES is safe and effective in the short term and can improve long-term clinical outcomes is not known. METHODS: In an international, 2:1 randomized, single-blind trial, we compared treatment with Supreme DES to durable polymer everolimus-eluting stents (DP-EES) in patients with acute and chronic coronary syndromes. The primary end point was target lesion failure—a composite of cardiac death, target vessel myocardial infarction, or clinically driven target lesion revascularization. The trial was designed to demonstrate noninferiority (margin of 3.58%) of the Supreme DES at 12 months compared with DP-EES (URL: https://www.clinicaltrials.gov; Unique identifier: NCT03168776). RESULTS: From October 2017 to July 2019, a total of 1629 patients were randomly assigned (2:1) to the Supreme DES (N=1086) or DP-EES (N=543). At 12 months, target lesion failure occurred in 57 of 1057 patients (5.4%) in the Supreme DES group and in 27 of 532 patients (5.1%) in the DP-EES group (absolute risk difference, 0.32% [95% CI, −1.87 to 2.5]; Pnoninferiority=0.002]. There were no significant differences in rates of device success, clinically driven target lesion revascularization, or stent thrombosis at 12 months, and the safety composite of cardiovascular death and target vessel myocardial infarction was 3.5% versus 4.6% (hazard ratio, 0.76 [95% CI, 0.46–1.25]) with Supreme DES compared with DP-EES, although rates of combined clinically and non–clinically driven target lesion revascularization at 12 months were higher with Supreme DES. CONCLUSIONS: Among patients with acute and chronic coronary syndromes undergoing percutaneous coronary intervention, the Supreme DES proved to be noninferior to the standard DP-EES