Gravitational wave detection by a spherical antenna: the angular sensitivity of resonators in the TIGA configuration and its variation with sidereal time and galactic longitude

Experimental projects using spherical antennas to detect gravitational waves are nowdays a concrete reality. The main purpose of this paper is to give a possible way of interpreting output data from such a system. Responses of the five fundamental quadrupole modes and of the six resonators in TIGA collocations are shown as a function of the incoming direction of the incident wave. Then, for a source lying in the galactic plane, sidereal time and galactic longitude dependence is given. Thus, once a candidate source of gravitational waves is considered, we can exactly predict the resonators' response as a function of time.Comment: 30 pages, 7 figure

Matched filter for multi-transducers resonant GW antennas

We analyze two kinds of matched filters for data output of a spherical resonant GW detector. In order to filter the data of a real sphere, a strategy is proposed, firstly using an omnidirectional in-line filter, which is supposed to select periodograms with excitations, secondly by performing a directional filter on such selected periodograms, finding the wave arrival time, direction and polarization. We point out that, as the analytical simplifications occurring in the ideal 6 transducers TIGA sphere do not hold for a real sphere, using a 5 transducers configuration could be a more convenient choice.Comment: 15 pages and 4 figures, version accepted for publication in PR

Sensitivity of a small matter-wave interferometer to gravitational waves

We study the possibility of using matter wave interferometry techniques to build a gravitational wave detector. We derive the response function and find that it contains a term proportional to the derivative of the gravitational wave, a point which has been disputed recently. We then study in detail the sensitivity that can be reached by such a detector and find that, if it is operated near resonance, it can reach potentially interesting values in the high frequency regime. The correlation between two or more of such devices can further improve the sensitivity for a stochastic signal.Comment: Revtex4, 19 pages, 3 figures. Several changes in the calculation of the response function. Accepted by PR

Alessandro Puglisi, "Le interazioni didattiche nei corsi di italiano online", Pacini Editore, Pisa 2021

Not availabl

“There is a secret down here” Traduzione di Life in the Iron Mills di Rebecca Harding Davis

Questo lavoro di tesi ha come obiettivo la traduzione di Life in the Iron Mills, racconto della scrittrice americana Rebecca Harding Davis. La traduzione dall’inglese è accompagnata da un lavoro di analisi stilistica e contenutistica del racconto e da un commento sulla traduzione. Gli strumenti utilizzati sono stati testi narratologici per l’analisi del testo e testi di teoria della traduzione

Usabilità ed efficacia di ambienti di apprendimento digitale in ambito linguistico

La pandemia scoppiata nel 2020 ha determinato il trasferimento della didattica in presenza a una mediata da uno schermo. Il cambiamento ha posto l'attenzione su tale modalità sollevando domande sulla sua organizzazione. Il contributo esplora tali temi e si focalizza sugli spazi formativi digitali, analizzati dal punto di vista dell'usabilità: tale concetto racchiude l'efficacia, la piacevolezza, la facilità d'uso di un sistema (Nielsen, 1994). In questo studio, sono stati presi in considerazione due sistemi: Moodle e WordPress. Entrambi hanno come obiettivo finale la gestione di contenuti digitali, ma con finalità diverse. Nelle due piattaforme, opportunamente allestite, sono state implementate alcune risorse aperte di italiano come L2. Per la raccolta di dati sono stati impiegati un software di monitoraggio del comportamento degli utenti, interviste e questionari. L'analisi dei dati ha fatto emergere indicazioni sull'esperienza di apprendimento degli utenti e sul loro comportamento, nonché sull'efficacia degli ambienti e dei materiali

La fruizione degli ambienti di apprendimento nella didattica dell’italiano L2

“The question of where people learn languages is equally as important as that of how they do so” (Benson, 2021). The paper explores the digital “where”, considering learning spaces for SLA. The literature offers a great deal of research about online learning but only a little on digital linguistic settings in interaction with learners. Students move within the spaces, they choose and select material, they construct their own path and knowledge. From the ecology of learning perspective, learning happens through the interaction with the environment (van Lier, 2004). Better understanding of that can help the teachers to comprehend the way students live and experience the learning platform. The study employed mixed methods which include qualitative and quantitative designs to have a more complete view of the problem. The data were collected through the observation of Italian as L2 students of the University G. D’Annunzio in classroom and within two different linguistic virtual contexts, an LMS[1]Moodle-based and a CMS[2] WordPress-based where digital resources for Italian as L2 were implemented. Thanks to the data analysis, it was possible to cast light on the construction of their own learning space and gave relevant suggestion about students’ behaviour. [1]Il Learning Management System è un software dedicato all’amministrazione, la documentazione, il tracciamento, i report e l’erogazione di corsi di formazione, corsi e interventi didattici.  [2]Il Content Management System è un software per la gestione, la creazione e la modifica di contenuti digitali. Alcuni esempi sono Wikipedia, le piattaforme per i blog o siti internet

Electronic contribution to the oscillations of a gravitational antenna

We carefully analyse the contribution to the oscillations of a metallic gravitational antenna due to the interaction between the electrons of the bar and the incoming gravitational wave. To this end, we first derive the total microscopic Hamiltonian of the wave-antenna system and then compute the contribution to the attenuation factor due to the electron-graviton interaction. As compared to the ordinary damping factor, which is due to the electron viscosity, this term turns out to be totally negligible. This result confirms that the only relevant mechanism for the interaction of a gravitational wave with a metallic antenna is its direct coupling with the bar normal modes.Comment: 25 pages, no figure

Microlensing modulation by quadrupole variation

We investigate microlensing in the case where the lens is considered as an extended object. We use a multipolar expansion of the lens potential and show that the time-varying nature of the quadrupole contribution allows to separate it from the mass and spin contributions and leads to specific modulations of the amplification signal. As example we study the case of binary system lenses in our galaxy. The modulation is observable if the rotation period of the system is smaller than the time over which the amplification is significant and if the impact parameter of the passing light ray is sufficiently close to the Einstein radius so that the amplification is large. Observations of this modulation can reveal important information on the quadrupole and thus on the gravitational radiation emitted by the binary lens. Even if not observed directly, because of their importance the quadrupole modulation has to be included in the error budget for high magnification ($\mu\leq7$) microlensing events.Comment: Matches publicated versio