Mathematical Formulation of Multi-Layer Networks

A network representation is useful for describing the structure of a large variety of complex systems. However, most real and engineered systems have multiple subsystems and layers of connectivity, and the data produced by such systems is very rich. Achieving a deep understanding of such systems necessitates generalizing "traditional" network theory, and the newfound deluge of data now makes it possible to test increasingly general frameworks for the study of networks. In particular, although adjacency matrices are useful to describe traditional single-layer networks, such a representation is insufficient for the analysis and description of multiplex and time-dependent networks. One must therefore develop a more general mathematical framework to cope with the challenges posed by multi-layer complex systems. In this paper, we introduce a tensorial framework to study multi-layer networks, and we discuss the generalization of several important network descriptors and dynamical processes --including degree centrality, clustering coefficients, eigenvector centrality, modularity, Von Neumann entropy, and diffusion-- for this framework. We examine the impact of different choices in constructing these generalizations, and we illustrate how to obtain known results for the special cases of single-layer and multiplex networks. Our tensorial approach will be helpful for tackling pressing problems in multi-layer complex systems, such as inferring who is influencing whom (and by which media) in multichannel social networks and developing routing techniques for multimodal transportation systems.Comment: 15 pages, 5 figure

Depression and attachment: how do personality styles and social support influence this relation?

The purpose of this study is to improve the current understanding of the relation between depression and attachment through the evaluation of the role of personality styles (dependent vs self-critical) and social support in this association. These variables were studied in a clinical sample of 70 depressed outpatients (83% women; M=41.47 years, SD=12.91). Depressive symptomatology was assessed through the Beck Depression Inventory, adult attachment through the Experiences in Close Relationships Scale, social support through the Social Support Questionnaire and dependency and self-criticism through the Depressive Experiences Questionnaire. Mediational and moderation regression analyses were performed. Results show that the association between the dimensions of attachment (anxiety and avoidance) and depression was partially mediated by self-criticism. Furthermore, results demonstrate the role of social support as a moderating variable: when the level of satisfaction with social support was low and the anxiety dimension in the attachment scale was high, as avoidance increased, depressive symptoms increased as well. Results are discussed in relation to their importance for understanding the complex interplay of the variables involved in depression

Discovery of X-ray polarization angle rotation in active galaxy Mrk 421

The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can track how the magnetic field changes in the flow of the radiating particles by observing rotations of the electric vector position angle $\Psi$. Here we report the discovery of a $\Psi_{\mathrm x}$ rotation in the X-ray band in the blazar Mrk 421 at an average flux state. Across the 5 days of Imaging X-ray Polarimetry Explorer (IXPE) observations of 4-6 and 7-9 June 2022, $\Psi_{\mathrm x}$ rotated in total by $\geq360^\circ$. Over the two respective date ranges, we find constant, within uncertainties, rotation rates ($80 \pm 9$ and $91 \pm 8 ^\circ/\rm day$) and polarization degrees ($\Pi_{\mathrm x}=10\%\pm1\%$). Simulations of a random walk of the polarization vector indicate that it is unlikely that such rotation(s) are produced by a stochastic process. The X-ray emitting site does not completely overlap the radio/infrared/optical emission sites, as no similar rotation of $\Psi$ was observed in quasi-simultaneous data at longer wavelengths. We propose that the observed rotation was caused by a helical magnetic structure in the jet, illuminated in the X-rays by a localized shock propagating along this helix. The optically emitting region likely lies in a sheath surrounding an inner spine where the X-ray radiation is released

The next generation cameras for the Large-Sized Telescopes of the Cherenkov Telescope Array Observatory

International audienceThe latest generation of silicon photomultipliers (SiPM) offers twice as much sensitivity to Cherenkov light observed at ground level when compared to photomultipliers.Their use for imaging atmospheric Cherenkov telescopes is increasing, from the FACT telescope, the pioneer, to the small-sized telescopes of the Cherenkov Telescope Array (CTA) or the LHAASO WFCTA camera. The robustness of the SiPMs represents a unique opportunity to ensure long-term operation with low maintenance.In this work, we present the latest developments and performance of a SiPM camera aiming at upgrading the large-sized telescopes (LST) cameras of CTA.The SiPM camera, equipped with 0.05 deg pixels, provides images of improved resolution for better feature extraction. The increase in the number of pixels has driven the development of low-power front-end electronics whose design is presented in this work. We also present the fully digital readout architecture of the proposed camera, which will enable the implementation of novel triggering algorithms based on artificial intelligence

Paisaje Cultural Urbano e Identitad Territorial

Linguaggio contemporaneo e preesistenze: dialogo in un mondo globalizzato Il tema del rapporto con l’antico trova una giusta dimensione operativa quando, superando la sfera delle ideologie e quella delle opposte ragioni della memoria e dello sviluppo, indirizza positivamente l’azione progettuale ora per differenza ora per empatia, a seconda delle circostanze, ma crea sempre una forte tensione tra le ragioni dell’esistente e le necessità del nuovo. Intervenire nell’antico e per l’antico significa, pertanto, riprogettare il nostro modo di relazionarci con il passato, rinegoziandone identità e valori alla luce del nostro presente. Da questa angolazione il patrimonio non è solo lo spazio della memoria o quello della storia, ma diviene lo spazio del desiderio che trae alimento dal mito dell’araba fenice: esso, come principio evolutivo, rappresenta l’inizio di un incessante ricominciamento e l'occasione per una mediazione tra globale e locale