Search results for "Persio"
showing 7 items of 1107 documents
Competition of electron-phonon mediated superconductivity and Stoner magnetism on a flat band
2018
The effective attractive interaction between electrons, mediated by electron-phonon coupling, is a well-established mechanism of conventional superconductivity. In metals exhibiting a Fermi surface, the critical temperature of superconductivity is exponentially smaller than the characteristic phonon energy. Therefore, such superconductors are found only at temperatures below a few kelvin. Systems with flat energy bands have been suggested to cure the problem and provide a route to room-temperature superconductivity, but previous studies are limited to only BCS models with an effective attractive interaction. Here we generalize Eliashberg's theory of strong-coupling superconductivity to syst…
Engineered surface waves in hyperbolic metamaterials
2013
We analyzed surface-wave propagation that takes place at the boundary between a semi-infinite dielectric and a multilayered metamaterial, the latter with indefinite permittivity and cut normally to the layers. Known hyperbolization of the dispersion curve is discussed within distinct spectral regimes, including the role of the surrounding material. Hybridization of surface waves enable tighter confinement near the interface in comparison with pure-TM surface-plasmon polaritons. We demonstrate that the effective-medium approach deviates severely in practical implementations. By using the finite-element method, we predict the existence of long-range oblique surface waves. This research was fu…
Génération de similaritons optiques à 1550 nm par amplification Raman dans une fibre NZ-DSF
2004
Nous presentons la premiere observation experimentale de similaritons optiques generes par amplification Raman a 1550 nm dans une fibre a dispersion decalee. Une caracterisation FROG des impulsions indique un profil d'intensite parabolique et un chirp lineaire conformes aux predictions theoriques.
Tube transport of water vapor with condensation and desorption
2013
Attenuation and delay of active tracers in tube transport is an important current problem, but its full explanation is still lacking. To this end a model is introduced, where part of a tracer undergoes condensation and evaporation, treated as a diffusion-type process, in addition to Taylor dispersion. Condensation of water was verified by high-speed imaging, and the model solution fitted the breakthrough curves of laboratory measurements with pulses of water vapor of varying relative humidity. The model provides a transfer function whose performance was verified against field measurements. peerReviewed
Riconfigurare i territori metroplitani. Forme di urbanizzazione e fenomeni di pressione insediativa sui sistemi di interesse naturale in Sicilia
2018
The consumption of the soil due to urbanization it is a phenomena already for many years under observations, but of which only the scientific environment has noticed the elevated environmental impact progress. From a disciplinary point of view, is possible to identify a line of research focusing on the analysis and identification of new morphologies of urbanization and on the interaction among different settlement patterns coexisting in a specific context. This reading complements with the scientific production about the forms of settlement pressure on environmental systems, producing change and deterioration on natural ecosystems and loss of biodiversity. A necessary reference for this lin…
Orientamento e inclusione: uno studio di caso nelle scuole secondarie palermitane di primo grado
2017
This paper presents the main results of the research work that promoted the design and implementation of training and guidance played in the territory of Palermo during the school years 2013/2014 and 2014/2015 in three secondary schools, with operating procedures, capable of promoting inclusive paths, based on the involvement of students, teachers and parents. The assumption from which we started is that the problems of dispersion and social marginalization can be addressed not only through direct guidance interventions with young people at risk, but also involving adults of reference because we are convinced that this will have, even at a distance of time a significant impact on students. …
Effect of the submerged vegetation distribution on flow characteristics and lateral dispersion: Experimental analysis at the apex section of a meande…
2020
Understanding of how the vegetation distribution influences flow patterns and turbulence structure is extremely important to analyse environmental processes as the sediment transport and the mixing of transported quantities. In the present paper attention is focused on the effect of flexible vegetation on flow characteristics and dispersion processes at the apex section of a large-amplitude meandering bend. The analysis is conducted with the aid of data collected in a laboratory meandering flume both in the absence of vegetation on the bed and in the presence of real and flexible vegetation on the bed. Results show that the presence of vegetation affects both the lateral dispersion coeffici…