Hub Synchronization in Scale-Free Networks

Heterogeneity in the degree distribution is known to suppress global synchronization in complex networks of symmetrically coupled oscillators. Scale-free networks display a great deal of heterogeneity, containing a few nodes, termed hubs, that are highly connected, while most nodes receive only a few connections. Here, we show that a group of synchronized nodes may appear in scale-free networks: hubs undergo a transition to synchronization while the other nodes remain unsynchronized. This general phenomenon can occur even in the absence of global synchronization. Our results suggest that scale-free networks may have evolved to complement various levels of synchronization.Comment: 4 pages, 1 figur

Role of Quantumness of Correlations in Entanglement Resource Theory

Quantum correlations: entanglement and quantumness of correlations are main resource for quantum information theory. In this chapter it is presented the scenarios which quantumness of correlations plays an interesting role in entanglement distillation protocol. By means of Koashi - Winter relation, it is discussed that quantumness of correlations are related to the irreversibility of the entanglement distillation protocol. The activation protocol is introduced, and it is proved that quantumness of correlations can create distillable entanglement between the system and the measurement apparatus during a local measurement process.Comment: Full chapter contribution of Advanced Technologies of Quantum Key Distribution, ISBN 978-953-51-5289-

Social media and tourism : a wishful relationship

For decades hospitality firms were used to domain the communication process. Thematic social network sites such as TripAdvisor became very important tools for travelers when deciding which hotels to book, and what restaurants and tourist attractions to visit, been a visible part of tourism communication evolution. Evidence suggests that e-WOM serves as a primary information source when tourists choose destinations, hotels, and other experiences. The role and use of social media in tourists’ decision making has been widely discuss in tourism and hospitality research, especially in the research phase of the tourist’ travel planning process. With the wide adoption of social media the influence of customers’ word-of-mouth increased and influences not only the research phase, but the repetition and overall customers’ experiences. To answer these questions a model assessing e-wom was developed and data was gathering from TripAdvisor regarding customer’s opinion in restaurant experiences. The results found establish the bases for understanding tourists’ engagement level and profiles.N/

Model selection and hypothesis testing for large-scale network models with overlapping groups

The effort to understand network systems in increasing detail has resulted in a diversity of methods designed to extract their large-scale structure from data. Unfortunately, many of these methods yield diverging descriptions of the same network, making both the comparison and understanding of their results a difficult challenge. A possible solution to this outstanding issue is to shift the focus away from ad hoc methods and move towards more principled approaches based on statistical inference of generative models. As a result, we face instead the more well-defined task of selecting between competing generative processes, which can be done under a unified probabilistic framework. Here, we consider the comparison between a variety of generative models including features such as degree correction, where nodes with arbitrary degrees can belong to the same group, and community overlap, where nodes are allowed to belong to more than one group. Because such model variants possess an increasing number of parameters, they become prone to overfitting. In this work, we present a method of model selection based on the minimum description length criterion and posterior odds ratios that is capable of fully accounting for the increased degrees of freedom of the larger models, and selects the best one according to the statistical evidence available in the data. In applying this method to many empirical unweighted networks from different fields, we observe that community overlap is very often not supported by statistical evidence and is selected as a better model only for a minority of them. On the other hand, we find that degree correction tends to be almost universally favored by the available data, implying that intrinsic node proprieties (as opposed to group properties) are often an essential ingredient of network formation.Comment: 20 pages,7 figures, 1 tabl

Polymers with nearest- and next nearest-neighbor interactions on the Husimi lattice

The exact grand-canonical solution of a generalized interacting self-avoid walk (ISAW) model, placed on a Husimi lattice built with squares, is presented. In this model, beyond the traditional interaction $\omega_1=e^{\epsilon_1/k_B T}$ between (nonconsecutive) monomers on nearest-neighbor (NN) sites, an additional energy $\epsilon_2$ is associated to next-NN (NNN) monomers. Three definitions of NNN sites/interactions are considered, where each monomer can have, effectively, at most 2, 4 or 6 NNN monomers on the Husimi lattice. The phase diagrams found in all cases have (qualitatively) the same thermodynamic properties: a non-polymerized (NP) and a polymerized (P) phase separated by a critical and a coexistence surface that meet at a tricritical ($\theta$-) line. This $\theta$-line is found even when one of the interactions is repulsive, existing for $\omega_1$ in the range $[0,\infty)$, i. e., for $\epsilon_1/k_B T$ in the range $[-\infty,\infty)$. Counterintuitively, a $\theta$-point exists even for an infinite repulsion between NN monomers ($\omega_1=0$), being associated to a coil-"soft globule" transition. In the limit of an infinite repulsive force between NNN monomers, however, the coil-globule transition disappears and only a NP-P continuous transition is observed. This particular case, with $\omega_2=0$, is also solved exactly on the square lattice, using a transfer matrix calculation, where a discontinuous NP-P transition is found. For attractive and repulsive forces between NN and NNN monomers, respectively, the model becomes quite similar to the semiflexible-ISAW one, whose crystalline phase is not observed here, as a consequence of the frustration due to competing NN and NNN forces. The mapping of the phase diagrams in canonical ones is discussed and compared with recent results from Monte Carlo simulations.Comment: 21 pages, 6 figure