Additional Light Waves in Hydrodynamics and Holography

We study the phenomenon of additional light waves (ALWs), observed in crystal optics: two or more electromagnetic waves with the same polarization, but different refractive index, propagate simultaneously in a isotropic medium. We show that ALWs are common in relativistic hydrodynamics, and in particular in strongly coupled systems that admit a dual gravitational description, where the ALWs are dual to quasi normal modes in the AdS gravity. We study both the transverse and the longitudinal light wave propagation. In the longitudinal channel we find a transition between regimes with different number of excitonic resonances which resembles the transition to standard optics observed in crystals.Comment: 20 pages, 17 figure

Nonequilibrium and effect of gas mixtures in an atmospheric microplasma

The gas and effective electron temperatures have been estimated for atmospheric microplasma by means of optical emission spectroscopy. The results have shown that the microplasma exhibits nonequilibrium and, as its size is reduced, the two temperatures depart from each other, enhancing the nonequilibrium characteristic. The effect of methane and oxygen concentrations has also been studied, showing that gas mixtures have an important effect on the microplasma state

Seven missing damaging earthquakes in Upper Valtiberina (Central Italy) in 16th-18th century: research strategies and historical sources

The Italian earthquake catalogue is considered to be fairly complete starting from the 17th century and for classes of earthquakes of magnitude greater than 5.5. However, dedicated historical research has highlighted the fact that even in areas believed to be well-recognised from the seismological standpoint, authoritative traces of local earthquakes that have caused damage may also emerge. In this study, we present the results of a pilot study performed for the Upper Valtiberina within the framework of the INGV research programmes in the years 1999-2001, expanded and revised in 2005. The study highlighted seven local medium intensity earthquakes, which nonetheless caused damage to buildings. Besides the results, which as a whole have allowed us to classify 18 effects in 6 sites, the research method adopted is also presented. It is a method applicable to other cases as well, where the chronological earthquake indicators are unknown, being capable of unearthing earthquakes unknown to the tradition of seismological studies and the catalogues in use. A selection of the manuscript sources used is presented in the Appendix

Are Coworkers in the Italian Peripheral Areas Performing Better? A Counterfactual Analysis

Coworking spaces are “serendipity accelerators” designed to host creative people and entrepreneurs. While recent literature has started exploring the indirect effects of coworking spaces on the local context, little is still known on how coworking spaces may directly affect the coworkers’ economic performance and wellbeing. Using a novel dataset based on a survey of 326 CWs working in the Italian coworking spaces in 2018, this paper explores the potential economic impact for coworkers, depending on whether a coworking space is localized in a peripheral or an urban area. Through a propensity-score matching approach, we found that being located in a peripheral area for coworkers may represent an opportunity to earn more than working in an urban center. The same holds for the organization coworkers belong to

I terremoti e i maremoti dello Stretto di Messina dal mondo antico alla fine del XX secolo: descrizioni e parametri

Un excursus storico di oltre duemila anni sintetizza le conoscenze attestate da fonti scritte. Antiche testimonianze, annotazioni in codici medievali, ma anche dettagliate relazioni di epoca moderna e rilevazioni contemporanee consentono di delineare un quadro il più possibile completo della sismicità di quest’area, abitata fin dai tempi più remoti. Emergono diversi terremoti minori, alcuni dei quali quasi dimenticati, che tuttavia confermano un’immagine dell’attività sismica nell’area dello Stretto caratterizzata da eventi frequenti, ma dominata da rari terremoti catastrofici