Tourism market segmentation of Italian families for the summer season

In last decades, the rapid expansion of tourism sector and the major differentiation of the tourism products have stimulated several studies in segmentation of tourism markets; but the applications of that technique has always focused on single consumers, while often the real "buyer" is the family. In this paper, we deal with national leisure tourism of Italian families in summer season; for the analysis, a sample of around 3,500 Italian families from a multi-scope sample survey "Travels and Holidays", collected by the National Institute of Statistics (ISTAT) is used. The major objective of this study is to investigate holiday strategies of Italian families in connection with recent changes in family structure, in order to individuate different profiles and different customs in travel patterns

Interplay of superradiance and disorder in the Anderson Model

Using a non-Hermitian Hamiltonian approach to open systems, we study the interplay of disorder and superradiance in a one-dimensional Anderson model. Analyzing the complex eigenvalues of the non-Hermitian Hamiltonian, a transition to a superradiant regime is shown to occur. As an effect of openness the structure of eigenstates undergoes a strong change in the superradiant regime: we show that the sensitivity to disorder of the superradiant and the subradiant subspaces is very different; superradiant states remain delocalized as disorder increases, while subradiant states are sensitive to the degree of disorder.Comment: 7 pages, submitted to the special issue on "Physics with non-Hermitian operators: Theory and Experiment" of the journal "Fortschritte der Physik - Progress of Physics

Travel Profiles Of Family Holidays In Italy

Family represents the most important and emotive connection among humans. In tourism sector, it is the consumer base of the industry; however, the importance of family in travel market is not reflected in tourism research, even if family holiday market has been identified as constituting a major portion of leisure travels around the world. Furthermore, travel choices are clearly influenced by the composition and the characteristics of the families. In this paper, we analyse family holidays in the Italian context; for the purpose of this study, from ISTAT multipurpose survey we use a sample of around 2,000 holidays made in 2013 by almost two components of the same family. The goal is to classify family holidays, and detect their profile

Shielding and localization in presence of long range hopping

We investigate a paradigmatic model for quantum transport with both nearest-neighbor and infinite range hopping coupling (independent of the position). Due to long range homogeneous hopping, a gap between the ground state and the excited states can be induced, which is mathematically equivalent to the superconducting gap. In the gapped regime, the dynamics within the excited states subspace is shielded from long range hopping, namely it occurs as if long range hopping would be absent. This is a cooperative phenomenon since shielding is effective over a time scale which diverges with the system size. We named this effect {\it Cooperative Shielding}. We also discuss the consequences of our findings on Anderson localization. Long range hopping is usually thought to destroy localization due to the fact that it induces an infinite number of resonances. Contrary to this common lore we show that the excited states display strong localized features when shielding is effective even in the regime of strong long range coupling. A brief discussion on the extension of our results to generic power-law decaying long range hopping is also given. Our preliminary results confirms that the effects found for the infinite range case are generic.Comment: 7 pages, 9 figur

Optimal efficiency of quantum transport in a disordered trimer

Disordered quantum networks, as those describing light-harvesting complexes, are often characterized by the presence of peripheral ring-like structures, where the excitation is initialized, and inner reaction centers (RC), where the excitation is trapped. The peripheral rings display coherent features: their eigenstates can be separated in the two classes of superradiant and subradiant states. Both are important to optimize transfer efficiency. In the absence of disorder, superradiant states have an enhanced coupling strength to the RC, while the subradiant ones are basically decoupled from it. Static on-site disorder induces a coupling between subradiant and superradiant states, creating an indirect coupling to the RC. The problem of finding the optimal transfer conditions, as a function of both the RC energy and the disorder strength, is very complex even in the simplest network, namely a three-level system. In this paper we analyze such trimeric structure choosing as initial condition a subradiant state, rather than the more common choice of an excitation localized on a site. We show that, while the optimal disorder is of the order of the superradiant coupling, the optimal detuning between the initial state and the RC energy strongly depends on system parameters: when the superradiant coupling is much larger than the energy gap between the superradiant and the subradiant levels, optimal transfer occurs if the RC energy is at resonance with the subradiant initial state, whereas we find an optimal RC energy at resonance with a virtual dressed state when the superradiant coupling is smaller than or comparable with the gap. The presence of dynamical noise, which induces dephasing and decoherence, affects the resonance structure of energy transfer producing an additional 'incoherent' resonance peak, which corresponds to the RC energy being equal to the energy of the superradiant state.Comment: This article shares part of the introduction and most of Section II with arXiv:1508.01613, the remaining parts of the two articles treat different problem

Multi-mode partitioning for text clustering to reduce dimensionality and noises

Co-clustering in text mining has been proposed to partition words and documents simultaneously. Although the main advantage of this approach may improve interpretation of clusters on the data, there are still few proposals on these methods; while one-way partition is even now widely utilized for information retrieval. In contrast to structured information, textual data suffer of high dimensionality and sparse matrices, so it is strictly necessary to pre-process texts for applying clustering techniques. In this paper, we propose a new procedure to reduce high dimensionality of corpora and to remove the noises from the unstructured data. We test two different processes to treat data applying two co-clustering algorithms; based on the results we present the procedure that provides the best interpretation of the data

The Topological Non-connectivity Threshold in quantum long-range interacting spin systems

Quantum characteristics of the Topological Non-connectivity Threshold (TNT), introduced in F.Borgonovi, G.L.Celardo, M.Maianti, E.Pedersoli, J. Stat. Phys., 116, 516 (2004), have been analyzed in the hard quantum regime. New interesting perspectives in term of the possibility to study the intriguing quantum-classical transition through Macroscopic Quantum Tunneling have been addressed.Comment: contribution to NEXTSIGMAPHI 3r

Cooperative shielding in many-body systems with long-range interaction

In recent experiments with ion traps, long-range interactions were associated with the exceptionally fast propagation of perturbation, while in some theoretical works they have also been related with the suppression of propagation. Here, we show that such apparently contradictory behavior is caused by a general property of long-range interacting systems, which we name "Cooperative Shielding". It refers to shielded subspaces that emerge as the system size increases and inside of which the evolution is unaffected by long-range interactions for a long time. As a result, the dynamics strongly depends on the initial state: if it belongs to a shielded subspace, the spreading of perturbation satisfies the Lieb-Robinson bound and may even be suppressed, while for initial states with components in various subspaces, the propagation may be quasi-instantaneous. We establish an analogy between the shielding effect and the onset of quantum Zeno subspaces. The derived effective Zeno Hamiltonian successfully describes the short-ranged dynamics inside the subspaces up to a time scale that increases with system size. Cooperative Shielding can be tested in current experiments with trapped ions.Comment: 9 pages, 5 figures (accepted at Phys. Rev. Lett.

Cooperative Robustness to Static Disorder: Superradiance and localization in a nanoscale ring to model natural light-harvesting systems

We analyze a 1-d ring structure composed of many two-level systems, in the limit where only one excitation is present. The two-level systems are coupled to a common environment, where the excitation can be lost, which induces super and subradiant behavior, an example of cooperative quantum coherent effect. We consider time-independent random fluctuations of the excitation energies. This static disorder, also called inhomogeneous broadening in literature, induces Anderson localization and is able to quench Superradiance. We identify two different regimes: $i)$ weak opening, in which Superradiance is quenched at the same critical disorder at which the states of the closed system localize; $ii)$ strong opening, with a critical disorder strength proportional to both the system size and the degree of opening, displaying robustness of cooperativity to disorder. Relevance to photosynthetic complexes is discussed.Comment: 12 pages, 7 figs., Superradiance, Anderson Localization, Cooperative effects. Accepted for publication in Phys. Rev.