Grouping complex systems: a weighted network comparative analysis

In this study, the authors compare two inter-municipal commuting networks (MCN) pertaining to the Italian islands of Sardinia and Sicily, by approaching their characterization through a weighted network analysis. They develop on the results obtained for the MCN of Sardinia (De Montis et al. 2007) and attempt to use network analysis as a mean of detection of similarities or dissimilarities between the systems at hand

Modeling commuting systems through a complex network analysis: a study of the Italian islands of Sardinia and Sicily

This study analyzes the inter-municipal commuting systems of the Italian islands of Sardinia and Sicily, employing weighted network analysis technique. Based on the results obtained for the Sardinian commuting network, the network analysis is used to identify similarities and dissimilarities between the two systems

Excursion set theory for generic moving barriers and non-Gaussian initial conditions

Excursion set theory, where density perturbations evolve stochastically with the smoothing scale, provides a method for computing the mass function of cosmological structures like dark matter haloes, sheets and filaments. The computation of these mass functions is mapped into the so-called first-passage time problem in the presence of a moving barrier. In this paper we use the path-integral formulation of the excursion set theory developed recently to analytically solve the first-passage time problem in the presence of a generic moving barrier, in particular the barrier corresponding to ellipsoidal collapse. We perform the computation for both Gaussian and non-Gaussian initial conditions and for a window function which is a top-hat in wavenumber space. The expression of the halo mass function for the ellipsoidal collapse barrier and with non-Gaussianity is therefore obtained in a fully consistent way and it does not require the introduction of any form factor artificially derived from the Press-Schechter formalism based on the spherical collapse and usually adopted in the literatur

Conditional probabilities in the excursion set theory: generic barriers and non-Gaussian initial conditions

The excursion set theory, where density perturbations evolve stochastically with the smoothing scale, provides a method for computing the dark matter halo mass function. The computation of the mass function is mapped into the so-called first-passage time problem in the presence of a moving barrier. The excursion set theory is also a powerful formalism to study other properties of dark matter haloes such as halo bias, accretion rate, formation time, merging rate and the formation history of haloes. This is achieved by computing conditional probabilities with non-trivial initial conditions, and the conditional two-barrier first-crossing rate. In this paper we use the path integral formulation of the excursion set theory to calculate analytically these conditional probabilities in the presence of a generic moving barrier, including the one describing the ellipsoidal collapse, and for both Gaussian and non-Gaussian initial conditions. While most of our analysis associated with Gaussian initial conditions assumes Markovianity (top-hat in momentum space smoothing, rather than generic filters), the non-Markovianity of the random walks induced by non-Gaussianity is consistently accounted for. We compute, for a generic barrier, the first two scale-independent halo bias parameters, the conditional mass function and the halo formation time probability, including the effects of non-Gaussianities. We also provide the expression for the two-constant-barrier first-crossing rate when non-Markovian effects are induced by a top-hat filter function in real spac

La tutela dell'interesse legittimo al visto ed il diritto di migrare

In questo scritto ci si chiede, provando anche a dare una risposta a tale quesito, se il diritto "umano" alla liberà di movimento dentro e fuori i confini di uno Stato, nonché di residenza entro i confini dello stesso, sia un diritto universalmente riconosciuto, garantito e tutelato dagli Stati sovrani

Impact source localisation in aerospace composite structures

The most commonly encountered type of damage in aircraft composite structures is caused by low-velocity impacts due to foreign objects such as hail stones, tool drops and bird strikes. Often these events can cause severe internal material damage that is difficult to detect and may lead to a significant reduction of the structure's strength and fatigue life. For this reason there is an urgent need to develop structural health monitoring systems able to localise low-velocity impacts in both metallic and composite components as they occur. This article proposes a novel monitoring system for impact localisation in aluminium and composite structures, which is able to determine the impact location in real-time without a-priori knowledge of the mechanical properties of the material. This method relies on an optimal configuration of receiving sensors, which allows linearization of well-known nonlinear systems of equations for the estimation of the impact location. The proposed algorithm is based on the time of arrival identification of the elastic waves generated by the impact source using the Akaike Information Criterion. The proposed approach was demonstrated successfully on both isotropic and orthotropic materials by using a network of closely spaced surface-bonded piezoelectric transducers. The results obtained show the validity of the proposed algorithm, since the impact sources were detected with a high level of accuracy. The proposed impact detection system overcomes current limitations of other methods and can be retrofitted easily on existing aerospace structures allowing timely detection of an impact event.</p

Para-aortic lymphadenectomy in surgery for gastric cancer: current indications and future perspectives

Involvement of para-aortic nodes (PAN) has been detected at pathological examination in 10-25% of locally advanced gastric cancer. Based on these data of nodal diffusion, the lymphadenectomy of para-aortic stations would be desirable in locally advanced gastric cancer. However, the debate on the oncological benefit of para-aortic nodes dissection is still not solved. A review of the literature was performed and papers reporting either the rate of para-aortic nodal metastases or the long-term survival outcomes after D2+ para-aortic nodes dissection (PAND) or D3 lymphadenectomy were descriptively reported. The literature survey yielded 14 studies. Most of the papers show the outcome of series of advanced gastric cancer treated with surgery alone, while starting from 2012, 3 articles report the outcomes of D2 + PAND or D3 lymphadenectomy after preoperative chemotherapy. The rate of PAN metastases ranges between 8.5 and 28% in surgical series. Survival outcomes largely improved in series of patients treated with multimodal approach compared to those of surgery alone. In patients with clinically detected para-aortic nodal metastases, preoperative chemotherapy followed by PAND is indicated. More data are needed to clarify the indication to prophylactic PAND in the era of multimodal treatment, anyway super-extended lymphadenectomies have to be performed by experienced surgeons in dedicated centres