Topological properties of the bond-modulated honeycomb lattice

We study the combined effects of lattice deformation, e-e interaction and spin-orbit coupling in a two-dimensional (2D) honeycomb lattice. We adopt different kinds of hopping modulation--generalized dimerization and a Kekule distortion--and calculate topological invariants for the non-interacting system and for the interacting system. We identify the parameter range (Hubbard U, hopping modulation, spin-orbit coupling) where the 2D system behaves as a trivial insulator or Quantum Spin Hall Insulator.Comment: 8 pages, 4 figures: discussion improved, typos corrected, references updated. Matches version published in PR

On the low energy limit of one loop photon-graviton amplitudes

We present first results of a systematic study of the structure of the low energy limit of the one-loop photon-graviton amplitudes induced by massive scalars and spinors. Our main objective is the search of KLT-type relations where effectively two photons merge into a graviton. We find such a relation at the graviton-photon-photon level. We also derive the diffeomorphism Ward identity for the 1PI one graviton - N photon amplitudes.Comment: 14 pages, 1 figure. Final version to be published in Physics Letters

Topological invariants in interacting Quantum Spin Hall: a Cluster Perturbation Theory approach

Using Cluster Perturbation Theory we calculate Green's functions, quasi-particle energies and topological invariants for interacting electrons on a 2-D honeycomb lattice, with intrinsic spin-orbit coupling and on-site e-e interaction. This allows to define the parameter range (Hubbard U vs spin-orbit coupling) where the 2D system behaves as a trivial insulator or Quantum Spin Hall insulator. This behavior is confirmed by the existence of gapless quasi-particle states in honeycomb ribbons. We have discussed the importance of the cluster symmetry and the effects of the lack of full translation symmetry typical of CPT and of most Quantum Cluster approaches. Comments on the limits of applicability of the method are also provided.Comment: 7 pages, 7 figures: discussion improved, one figure added, references updated. Matches version published in New J. Phy

Smooth tensionful higher-codimensional brane worlds with bulk and brane form fields

Completely regular tensionful codimension-n brane world solutions are discussed, where the core of the brane is chosen to be a thin codimension-(n-1) shell in an infinite volume flat bulk, and an Einstein-Hilbert term localized on the brane is included (Dvali-Gabadadze-Porrati models). In order to support such localized sources we enrich the vacuum structure of the brane by the inclusion of localized form fields. We find that phenomenological constraints on the size of the internal core seem to impose an upper bound to the brane tension. Finite transverse-volume smooth solutions are also discussed.Comment: 1+14 pages, 2 figures; section 2.3 improved, typos corrected and references added. Published versio

The Silurian of Sardinia

The present volume “The Silurian of Sardinia” is composed of two related components. The first part comprises seven contributions introduced by an historical overview on the studies already carried out on the Silurian faunas of Sardinia. It aims to delineate a comprehensive scenario of the Silurian of Sardinia within a proper geological setting. A global overview regarding the palaeoenvironment and palaeogeography is also provided. The second part of the volume consists of seven research papers that illustrate actual knowledge on major fossil groups encountered in the Silurian limestones and shales of southern Sardinia

The conodont apparatus of Zieglerodina eladioi (Valenzuela Rios, 1994)

Zieglerodina eladioi (Valenzuela-Ríos) è una specie di conodonti ozarkodinidi documentata dalla parte più alta del Přídolí (Siluriano superiore) al Lochkoviano medio (Devoniano Inferiore). La specie è stata istituita nei Pirenei spagnoli e fino a ora è documentata in diverse aree del nord Gondwana (Marocco, Alpi Carniche, Sardegna, Repubblica Ceca e Turchia). L’apparato di Zieglerodina eladioi viene ricostruito basandosi su ritrovamenti in Marocco, Sardegna e nelle Alpi Carniche; esso comprende sei elementi (P1, P2, M, S0, S1 e S2) in cui gli elementi ramiformi sono caratterizzati da una denticolazione alternata con denticoli aghiformi. La morfologia dell’apparato conferma l’attribuzione della specie al genere Zieglerodina.Zieglerodina eladioi (Valenzuela-Ríos) is a small ozarkodinid from the latest Přídolí (Silurian) and the Lochkovian (Lower Devonian), up to now documented only in areas of North Gondwana. Material from Morocco, the Carnic Alps, and Sardinia provide the basis for the seximembrate reconstruction of this conodont species’ apparatus (consisting of P1, P2, M, S0, S1, and S2 elements). The ramiform elements of Zieglerodina eladioi are characterised by an alternate denticulation with spike-like denticles, further confirming the attribution of the species to the genus Zieglerodina

Famennian (Late Devonian) conodonts from the Pizzul West section (Carnic Alps, Italy)

Conodonts from the Pizzul West section are presented. \u7f e section is located in the Cason di Lanza/Mt. Zermula area of the central Carnic Alps and it exposes about twenty-four metres of Upper Devonian limestone. \u7f e forty-one taxa documented allow the discrimination of seven biozones of Frasnian and Famennian: Upper rhenana, Upper crepida, Uppermost crepida, Lower rhomboidea, Upper rhomboidea, Lower marginifera and Lower expansa

Effect of hydrophobic solutes on the liquid-liquid critical point

Jagla ramp particles, interacting through a ramp potential with two characteristic length scales, are known to show in their bulk phase thermodynamic and dynamic anomalies, similar to what is found in water. Jagla particles also exhibit a line of phase transitions separating a low density liquid phase and a high density liquid phase, terminating in a liquid-liquid critical point in a region of the phase diagram that can be studied by simulations. Employing molecular dynamics computer simulations, we study the thermodynamics and the dynamics of solutions of hard spheres (HS) in a solvent formed by Jagla ramp particles. We consider the cases of HS mole fraction x = 0.10, 0.15 and 0.20, and also the case x = 0.50 (a 1:1 mixture of HS and Jagla particles). We find a liquid-liquid critical point, up to the highest HS mole fraction; its position shifts to higher pressures and lower temperatures upon increasing x. We also find that the diffusion coefficient anomalies appear to be preserved for all the mole fractions studied.Comment: 8 pages, 7 figures, 1 table. In press (Phys. Rev. E

Cognitive and personality components underlying spoken idiom comprehension in context. An exploratory study.

In this exploratory study, we investigated whether and to what extent individual differences in cognitive and personality variables are associated with spoken idiom comprehension in context. Language unimpaired participants were enrolled in a cross-modal lexical decision study in which semantically ambiguous Italian idioms (i.e., strings with both a literal and an idiomatic interpretation as, for instance, break the ice), predictable or unpredictable before the string offset, were embedded in idiom-biasing contexts. To explore the contributions of different cognitive and personality components, participants also completed a series of tests respectively assessing general speed, inhibitory control, short-term and working memory, cognitive flexibility, crystallized and fluid intelligence, and personality. Stepwise regression analyses revealed that online idiom comprehension was associated with the participants\u2019 working memory, inhibitory control and crystallized verbal intelligence, an association modulated by idiom type. Also personality-related variables (State Anxiety and Openness to Experience) were associated with idiom comprehension, although in marginally significant ways. These results contribute to the renewed interest on how individual variability modulates language comprehension, and for the first time document contributions of individual variability on lexicalized, high frequency multi-word expressions as idioms adding new knowledge to the existing evidence on metaphor and sarcasm