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Humans engage with other humans and their surroundings through various modalities, most notably speech, sight, and touch. In a conversation, all these inputs provide an overview of how another person is feeling. When translating these modalities to a digital context, most of them are unfortunately lost. The majority of existing conversational recommender systems (CRSs) rely solely on natural language or basic click-based interactions. This work is one of the first studies to examine the influence of multi-modal interactions in a conversational food recommender system. In particular, we examined the effect of three distinct interaction modalities: pure textual, multi-modal (text plus visuals), and multi-modal supplemented with nutritional labeling. We conducted a user study (𝑁=195) to evaluate the three interaction modalities in terms of how effectively they supported users in selecting healthier foods. Structural equation modelling revealed that users engaged more extensively with the multi-modal system that was annotated with labels, compared to the system with a single modality, and in turn evaluated it as more effective.

Item does not contain fulltext XVI Congressus Internationalis Archaeologiae Christianae. Costantino e i costantinidi. L’innovazione costantiniana, le sue radici e i suoi sviluppi, 22 september 2013

A lot of studies support hypothesis that Multiple Sclerosis (MS) rises from interaction between genetic predisposition and environmental factors, not yet identified. As regards environmental factors, we investigated association between disease and exposure to smoking and coffee, wether in incidence or in progression of disease. We led a study by a case-control scheme 1:1, where comparison was between a MS patient and an healthy subject. MS patients (cases) were recognized among people attended in MS Ambulatory at the Neurosciences Department of University Hospital of Palermo. Healthy subjects (controls) were recognized by an epidemiological survey leaded on territory. Cases and controls were given a structured questionnaire to get up informations about cigarette smoking and coffee consumption. We included in our study 100 cases and 100 controls, matched to cases by sex. Our analyses show that MS patients were more exposed to smoking and to high coffee consumption before disease onset than general population, with a dose-dependent relationship (coffee: OR = 1.91, IC al 95% = 1,08-3,34; smoking: OR 3,27, IC al 95% = 1,82 - 5,89). That is true wether we consider separately these risk factors or we analyse them like associated events (OR = 3,65, IC al 95% 1,87 - 7,11). Instead of we did not found relationships between smoking, coffee and different clinical onset of disease. Using MSSS (Multiple Sclerosis Severity Score), we evaluated MS progression regarding smoking and/or coffee exposure during disease course and we did not notice a significant correlation between a possible worse disease progression and these two environmental factors (coffee: OR = 0,63, CI = 0,27 - 1,47; smoking: OR = 1,17, CI = 0,54 - 2,57). These results support hypothesis that cigarette smoking and high coffee consumption can be associated to an increased MS risk, slightly more if they are at the same time. On the contrary, these two environmental factors are not able to modify neither clinical onset type or disease progression in unfavourable way.

The electron of a H 2 + driven by a strong electromagnetic field induces molecular vibrations. Numerical and analytical results show that the molecule behaves as a parametric oscillator and can be treated as a kicked oscillator. The results are discussed from the point of view of the electron's periodic dressing and undressing processes.

Atoms, molecules , clusters and other systems driven by a strong laser field of frequency \omega_L can emit a spectrum of laser harmonics. The high harmonics generation (HHG) phenomen is strongly affected by the symmetries of the system. It is well known that systems with rotational symmetries emit only odd harmonics. Numerous researcher make mainly attention to the possibilities to set different initial conditions in order to control the spectrum. Recently, the study of nanotechnology is hot-topics and in particular the study of very symmetric systems such as fullerene, nanoring and structured nanoring (nanoring with identical and symmetric scattering centers). Therefore, it is natural and interestring to study the HHG emission from these systems and the effects of the symmetry break. In this poster we present the HHG spectrum emitted by a nanoring consisting of six symmetric scattering centers; as a second step we study the effects on the spectrum by small symmetry breakings. We show that tiny modifications of th symmetry allow a good control of the spectrum.

We use a 5-level system to investigate the HHG spectrum emitted by an atom driven by a linearly or elliptically polarized laser field. For this model the Schrodinger equation is numerically solved and we study the dipendence of the spectra, harmonic intensity and polarization of emitted radiation on the laser field ellipticity. Studying the intensity of the emitted radiation we find that un alsoder high laser ellipticity the harmonic emission is greatly reduced; the analysis of results shows that the harmonic intensity and the emitted radiation depend on the laser ellipticity.

Atomic and molecular systems, subjected to intense laser pulse, emit typical High-Order Armonic Generation (HHG) spectra. This work aims to investigate the possibility to obtain a laser device by HHG. At this end, we analyzed the emission spectra by a molecular ion driven by a linearly polarized laser field. The temporal behaviour is obtained using the Morlet wavelets transform of emission. The results show that, after filtration of the electromagnetic radiation emitted, it is possible to select a frequency which seems to have almost constant intensity and phase. This characteristic makes possible that HHG from a molecule can be used as high frequency laser fields.

We report on numerical results of energy spectra of photoelectrons emitted by irradiating an hydrogen atom with a relatively weak single attosecond XUV pulse in the presence of a two-color IR laser pulse. The densities of probabilities have been obtained by treating the interaction of the atom with the XUV radiation at the first order of the time-dependent perturbation theory and describing the emitted electron through the Coulomb-Volkov wavefunction. The results of the calculations agree with the ones found by numerically solving the time-dependent Schrödinger equation. Specifically, we use an algorithm that implements an high recision variant of the Cranck Nicolson integration method and allows to take into account the singularity in the Coulomb potential. Analysis of the spectra obtained for very long pulses show that certain features may be explained in terms of quantum interferences in the time domain.

We present the electromagnetic emission from one electron confined in a quantum ring driven by an intense laser field. We consider both a plain ring and one structured by six potential wells that produce a static tangential force. Through a suitable one-dimensional model we numerically solve the associated Schroedinger equation obtaining the correspondent time evolution of the wave-function. We show that the emission is formed by a wide plateau that can be both quasi-continuum or resolved in discrete lines. We study the dependence of the emitted spectra from the polarization status of the external laser field and in particular we concentrate on the intensity of the emitted lines and of their polarization characteristic. The results illustrate how the fabrication of such systems provide important practical sources of creation and control of the radiation. Moreover, the dynamic of the ring, studied from the classical point of view, presents interesting chaotic behavior and can represent an important example of transition from classical chaos to quantum behavior.

Laurel woodlands in the Madonie mountains (Sicily) are characterized by the presence of Laurus nobilis, Rhamnus lojaconoi and Vitis vinifera subsp. sylvestris. The results of a phytosociological study are presented, and a new endemic association, Rhamno lojaconoi–Lauretum nobilis, is described. Present Mediterranean laurel communities are the result of an adaptive response by Tertiary laurel forest to the peculiar microclimatic conditions that characterize the refugia where they persist. These refugia have been recently considered as a priority habitat under the Directive 92/43/EEC, and their plant communities are very vulnerable. Protection measures of the studied laurel populations are necessary, with particular reference to the bulking up of R. lojaconoi through in situ and ex situ propagation. A multivariate analysis of 63 relevés from all the Sicilian laurel communities described so far and additional 65 relevés from all over southern Europe and the Mediterranean basin bears out the autonomy of the new association, showing at the same time some oristic afnities between Sicilian, southern Italian, Spanish and Iberian associations. Their syntaxonomic treatment is discussed.

The radiation diffused by a one-dimensional homonuclear molecular ion driven by a laser field is studied as a function of the time. When the photon energy is resonant with the energy gap between the ground and the first excited state, the electronic probability density is seen to undergo slow and deep oscillations between the two nuclei. Synchronous to such oscillations, deep modulations of the emitted power are observed. The period of oscillation is of the order of 10 optical cycles. Detection of the variation in the intensity of the emitted electromagnetic spectrum therefore brings information on the position of the electron in the molecule.

A quantum ring driven by an intense laser field emits light in the form of high-harmonic radiation resulting from the strong acceleration experienced by the active electrons forced to move on a curved trajectory. The spectrum of the emitted light is rich and strongly dependent on the parameters of the problem. In order to investigate the physical origin of such variability, we focus on the seemingly simple problem of a laser-driven charge constrained to a ring from a classical standpoint. As it turns out, the dynamics of such a classical electron is governed by a nonlinear equation which results into a chaotic motion - by nature depending on the initial conditions in an unpredictable way. Our results indicate that the quantum harmonic spectra are reminiscent of the classical counterpart and suggest the existence of a line connecting the quantum and classical realms.

We study the polarization of the harmonics generated by a homonuclear diatomic molecule in the presence of an intense, linearly polarized laser field. The polarization parameters of the emitted radiation are investigated as function of the angle $\theta$ between the laser electric field and the molecular axis. The calculations are carried out by assuming a single active electron model with fixed nuclei; a two-dimensional model of the system is used. We find a different dependence of the parameters of the harmonics vs $\theta$ in the first or second half of the emitted spectrum. In particular, the differences are accentuated for $0^\circ < \theta < 50^\circ$, while for higher angles, until the perpendicular orientation, almost all the harmonics present similar characteristics

We present the dynamics of an electron constrained over an 1D ring with radius of 0.142 nm driven by a laser field. The temporal evolution of the system is evaluated by a semi-analytical solution of the full quantum time dependent Schr¨odinger equation. In our calculation the gap energy between the ground and the first excited state of the nanoring is three times the photon energy laser (0.63 eV) and the laser intensity is 4·1014 W/cm2 . Our analysis is performed by considering different polarization states of the incident laser. Our attention is mainly focused on the study of the High Harmonic Generation (HHG), the energy and the angular momentum absorbed by the driven system. We observe 1) that the harmonic yield is strongly dependent upon the pump polarization field and almost vanishes for circular polarization and 2) that the ring can be left in a state with average angular momentum different than zero. In figure we show the time average of the absorbed angular momentum (in atomic units) versus polarization angle (θ = 0◦ and θ = 90◦ correspond to linear polarization along x and y axes respectively; θ = 45◦ corresponds to circular polarization).

We study the full quantum dynamics of a simple molecular ion driven by an intense laser field. In particular we show that the quantum nature of the nuclear dynamics affects the emitted high harmonic generation (HHG) spectra, strongly reshaping the plateau region. In fact, it is evident that the characteristic flat trend is transformed into a descending trend, with the lower harmonics being two orders of magnitude more intense than the higher harmonics. We show that this effect is more pronounced in the lighter isotopic species of H$_2^+$ molecular ions and we also demonstrate that in this case the contribution to HHG from the antibonding electronic energetic surface is of the same order of magnitude as that from the bonding state.

The time-dependent wave function of a nanoring driven by a laser field is obtained by exploiting the symmetries inherent to the system and used for studying the properties of the electromagnetic radiation emitted by the nanoring as a function of the polarization state of the laser. The diffused radiation has the characteristics of high-order-harmonic generation. For a noncircularly polarized laser field an extension of the expected cutoff position is evident, indicating that nanorings are efficient sources of radiation. The polarization state of the emitted harmonics can be opportunely controlled by varying the parameters of the pump field. The profile of the absorbed angular moment shows that a magnetic moment can be induced depending on the polarization of the driven field.

High frequency lasing device by HHG

In this paper we discuss isotopic effects in simple molecular ions subjected to strong laser fields. We show that the intensity of the emitted spectra strongly depends upon both the nuclear mass of the molecular ions and the laser pulse duration. In particular, for short pulse duration [up to 8 optical cycles (o.c.)], we confirm the trend described in the most studied case in which the high-order harmonic generation is more efficient for heavier isotopes; in contrast, an interesting physical phenomenon is predicted for pulses longer than 16 o.c. characterized by an inverse effect in which lighter molecular species are responsible for higher-order harmonic emission.

The time dependent Schrodinger equation of a homonuclear diatomic molecule in the presence of a linearly polarized laser field is numerically solved by means of a split-operator parallel code. The calculations are carried out by assuming a single active electron model with fixed nuclei; a simplified two-dimensional model of the system is used. The highly nonlinear response of the electron wave function to the laser electric field stimulates the molecule to emit electromagnetic radiation consisting of a wide plateau of odd harmonics of the laser field. It is shown that the emitted spectrum can be finely controlled by changing the angle between the laser electric field and the molecular axis; this can be used to achieve a tunable source of high frequency radiation.