The period of a classical oscillator

We develop a simple method to obtain approximate analytical expressions for the period of a particle moving in a given potential. The method is inspired to the Linear Delta Expansion (LDE) and it is applied to a large class of potentials. Precise formulas for the period are obtained.Comment: 5 pages, 4 figure

Variational collocation for systems of coupled anharmonic oscillators

We have applied a collocation approach to obtain the numerical solution to the stationary Schr\"odinger equation for systems of coupled oscillators. The dependence of the discretized Hamiltonian on scale and angle parameters is exploited to obtain optimal convergence to the exact results. A careful comparison with results taken from the literature is performed, showing the advantages of the present approach.Comment: 14 pages, 10 table

Variational collocation on finite intervals

In this paper we study a new family of sinc--like functions, defined on an interval of finite width. These functions, which we call ``little sinc'', are orthogonal and share many of the properties of the sinc functions. We show that the little sinc functions supplemented with a variational approach enable one to obtain accurate results for a variety of problems. We apply them to the interpolation of functions on finite domain and to the solution of the Schr\"odinger equation, and compare the performance of present approach with others.Comment: 12 pages, 8 figures, 1 tabl

The emergence of AdS(2) from quantum fluctuations

We have shown how the quantization of two-dimensional quantum gravity with an action which contains only a positive cosmological constant and boundary cosmological constants leads to the emergence of a spacetime which can be described as a constant negative curvature spacetime with superimposed quantum fluctuations.Comment: 4 pages. Talk given by W. Westra at the Eleventh Marcel Grossmann Meeting on General Relativity at the Freie U. Berlin, July 23 - 29, 200

A new representation for non--local operators and path integrals

We derive an alternative representation for the relativistic non--local kinetic energy operator and we apply it to solve the relativistic Salpeter equation using the variational sinc collocation method. Our representation is analytical and does not depend on an expansion in terms of local operators. We have used the relativistic harmonic oscillator problem to test our formula and we have found that arbitrarily precise results are obtained, simply increasing the number of grid points. More difficult problems have also been considered, observing in all cases the convergence of the numerical results. Using these results we have also derived a new representation for the quantum mechanical Green's function and for the corresponding path integral. We have tested this representation for a free particle in a box, recovering the exact result after taking the proper limits, and we have also found that the application of the Feynman--Kac formula to our Green's function yields the correct ground state energy. Our path integral representation allows to treat hamiltonians containing non--local operators and it could provide to the community a new tool to deal with such class of problems.Comment: 9 pages ; 1 figure ; refs added ; title modifie

Progetto di una banca dati multidisciplinare: il progetto europeo VOLUME come caso di studio

Il presente lavoro si pone come obiettivo la realizzazione di una banca dati multi-parametrica in grado di archiviare diverse tipologie di dato strumentale. Il sistema proposto, accessibile dal portale dell’INGV della sezione di Catania al link “altre INGV-CT” del menù “Banche dati”, studiato e collaudato all’interno del progetto europeo VOLUME (http://www.volume-project.net/), consente la fruizione dei dati messi a disposizione dalle diverse unità funzionali dell’INGV della sezione di Catania coinvolte nel progetto. I dati, disponibili ai partner del progetto, sono accessibili previa registrazione e successiva validazione dell’utente. L’obiettivo principale di tale progetto è quello di studiare le dinamiche vulcaniche in modo da identificare e caratterizzare fenomeni che possano essere interpretati come possibili precursori di eruzioni. Per perseguire tale obiettivo occorre analizzare ed integrare diverse tipologie di misure, da quelle geofisiche a quelle geochimiche, con il fine di raggiungere una migliore comprensione dei processi in atto all’interno delle aree caratterizzate da vulcanismo attivo. Sebbene i dati archiviati siano relativi al solo vulcano Etna ed il periodo analizzato è relativo agli anni 2002-2003 , il sistema proposto può essere impiegato per la gestione di dati relativi ad altri vulcani e attinenti a qualsiasi intervallo temporale. Il sistema è stato realizzato in modo da fornire una interfaccia web user friendly che permetta agli utenti la navigazione, la visualizzazione e il download dei dati memorizzati all’interno della banca dati. Nei paragrafi successivi verrà presentata una panoramica delle funzionalità implementate per la navigazione del database. In particolare, i dati trattati nel presente report sono stati prodotti e forniti dalle unità funzionali dell’INGV della sezione di Catania (http://www.ct.ingv.it) che hanno partecipato al progetto VOLUME: • Unità Funzionale Sismologia; • Unità Funzionale Vulcanologia e Geochimica; • Unità Funzionale Gravimetria e Magnetismo; • Unità Funzionale Deformazione e Geodesia

Colour superconductivity in finite systems

In this paper we study the effect of finite size on the two-flavour colour superconducting state. As well as restricting the quarks to a box, we project onto states of good baryon number and onto colour singlets, these being necessary restrictions on any observable ``quark nuggets''. We find that whereas finite size alone has a significant effect for very small boxes, with the superconducting state often being destroyed, the effect of projection is to restore it again. The infinite-volume limit is a good approximation even for quite small systems.Comment: 14 pages RevTeX4, 12 eps figure

Presence of Candida zemplinina in Sicilian Musts and Selection of a Strain for Wine Mixed Fermentations

The purpose of this work was to investigate the presence of C. zemplinina yeasts in Sicilian musts andgrapes and to identify strains of oenological interest. We report on the taxonomical reclassificationof Candida yeast isolates from Sicilian musts and on the selection of one strain of oenological interest(Cz3), based on mixed micro-fermentation experiments in sterile Nero d’Avola musts. Our results showthat Candida zemplinina is abundant in Sicilian grapes and musts, and that the Cz3 strain is suitablefor Candida zemplinina/Saccharomyces cerevisiae mixed fermentations. The higher glycerol content andthe lower ethanol level stood out as the most promising features of the wines obtained upon sequentialinoculation of the Cz3 and (S. cerevisiae) NDA21 yeast starters. We therefore have isolated a Sicilian Czstrain endowed with very promising features for the future development of mixed fermentation protocols