Managing the island territory : a historical perspective on sub-state nationalism in Corsica and Sardinia

Corsica (France) and Sardinia (Italy) are two islands of the western Mediterranean basin separated by a narrow strait. They share a problematic relationship with the mainland states to which they are associated, and from which they obtained their status of subnational island jurisdiction (SNIJ). The metropole/island relationship of these two islands is characterized by centrifugal tensions and the presence of sub-state nationalisms. These movements are different in terms of characteristics, strategies and electoral results, because of how France and Italy have managed the integration of the two islands, how the two island nationalisms have evolved, and how both metropolitan states have dealt with them. This article proposes a comparative history of Sardinian and Corsican nationalism and the relationship of Italy and France with these island territories. The intention is to analyse the two nationalisms, based almost exclusively on political science, with an historical perspective, highlighting the impact caused by the central states’ attitudes. In this way, the article points out how the differences between the political context of the two islands is defined by the different approach taken by France and Italy in managing their island territories.peer-reviewe

Wide band observations of the X-ray burster GS 1826-238

GS 1826-238 is a well-studied X-ray bursting neutron star in a low mass binary system. Thermal Comptonisation by a hot electron cloud is a widely accepted mechanism accounting for its high energy emission, while the nature of most of its soft X-ray output is not completely understood. A further low energy component is typically needed to model the observed spectra: pure blackbody and Comptonisation-modified blackbody radiation by a lower temperature (a few keV) electron plasma were suggested to explain the low energy data. We studied the steady emission of GS 1826-238 by means of broad band (X to soft Gamma-rays) measurements obtained by the INTEGRAL observatory in 2003 and 2006. The newly developed, up-to-date Comptonisation model CompTB is applied for the first time to study effectively the low-hard state variability of a low-luminosity neutron star in a low-mass X-ray binary system. We confirm that the 3-200 keV emission of \GS is characterised by Comptonisation of soft seed photons by a hot electron plasma. A single spectral component is sufficient to model the observed spectra. At lower energies, no direct blackbody emission is observed and there is no need to postulate a low temperature Compton region. Compared to the 2003 measurements, the plasma temperature decreased from 20 to 14 keV in 2006, together with the seed photons temperature. The source intensity was also found to be 30% lower in 2006, whilst the average recurrence frequency of the X-ray bursts significantly increased. Possible explanations for this apparent deviation from the typical limit-cycle behaviour of this burster are discussed.Comment: 6 pages, 2 figures. Accepted for publication in A&

A new model for the X-ray continuum of the magnetized accreting pulsars

Accreting highly magnetized pulsars in binary systems are among the brightest X-ray emitters in our Galaxy. Although a number of high statistical quality broad-band (0.1-100 keV) X-ray observations are available, the spectral energy distribution of these sources is usually investigated by adopting pure phenomenological models, rather than models linked to the physics of accretion. In this paper, a detailed spectral study of the X-ray emission recorded from the high-mass X-ray binary pulsars Cen X-3, 4U 0115+63, and Her X-1 is carried out by using BeppoSAX and joined Suzaku+NuStar data, together with an advanced version of the compmag model. The latter provides a physical description of the high energy emission from accreting pulsars, including the thermal and bulk Comptonization of cyclotron and bremsstrahlung seed photons along the neutron star accretion column. The compmag model is based on an iterative method for solving second-order partial differential equations, whose convergence algorithm has been improved and consolidated during the preparation of this paper. Our analysis shows that the broad-band X-ray continuum of all considered sources can be self-consistently described by the compmag model. The cyclotron absorption features, not included in the model, can be accounted for by using Gaussian components. From the fits of the compmag model to the data we inferred the physical properties of the accretion columns in all sources, finding values reasonably close to those theoretically expected according to our current understanding of accretion in highly magnetized neutron stars. The updated version of the compmag model has been tailored to the physical processes that are known to occur in the columns of highly magnetized accreting neutron stars and it can thus provide a better understanding of the high energy radiation from these sources.Comment: 19 pages, 10 figures, accepted for publication in A&

From Sardinian autonomist movement to the defense of the Second Republic

L’article vol evidenciar, en el marc de la intervenció dels antifeixistes italians en la Guerra Civil Espanyola, el paper jugat pels militants del Partit Sard d’Acció (PSd’A) i per alguns dels seus líders: Emilio Lussu (1890-1945) i Dino Giacobbe (1900-1985). En particular es tracta la contribució de Lussu en el debat teòric entre els antifeixistes italians sobre com organitzar la intervenció, així com les gestions dels dos militants per organitzar una unitat militar que representés la nació sarda dins del conflicte.The article deal with the italian antifascist intervention during the war, but wants to highlight the role played by the Sardinian Action Party and some of his leaders: Emilio Lussu (1890-1945) and Dino Giacobbe (1900-1985). It speaks about the positions of Lussu in the discussions between italians antifascists over the organization of the intervent, and then about the attempts carried out by the two militants to create a military unit that represents the sardinian nation in the spanish civil war

Algorithms for Graph-Constrained Coalition Formation in the Real World

Coalition formation typically involves the coming together of multiple, heterogeneous, agents to achieve both their individual and collective goals. In this paper, we focus on a special case of coalition formation known as Graph-Constrained Coalition Formation (GCCF) whereby a network connecting the agents constrains the formation of coalitions. We focus on this type of problem given that in many real-world applications, agents may be connected by a communication network or only trust certain peers in their social network. We propose a novel representation of this problem based on the concept of edge contraction, which allows us to model the search space induced by the GCCF problem as a rooted tree. Then, we propose an anytime solution algorithm (CFSS), which is particularly efficient when applied to a general class of characteristic functions called $m+a$ functions. Moreover, we show how CFSS can be efficiently parallelised to solve GCCF using a non-redundant partition of the search space. We benchmark CFSS on both synthetic and realistic scenarios, using a real-world dataset consisting of the energy consumption of a large number of households in the UK. Our results show that, in the best case, the serial version of CFSS is 4 orders of magnitude faster than the state of the art, while the parallel version is 9.44 times faster than the serial version on a 12-core machine. Moreover, CFSS is the first approach to provide anytime approximate solutions with quality guarantees for very large systems of agents (i.e., with more than 2700 agents).Comment: Accepted for publication, cite as "in press

Spectral evolution of bright NS LMXBs with INTEGRAL: an application of the thermal plus bulk Comptonization model

The aim of this work is to investigate in a physical and quantitative way the spectral evolution of bright Neutron Star Low-Mass X-ray Binaries (NS LMXBs), with special regard to the transient hard X-ray tails. We analyzed INTEGRAL data for five sources (GX 5-1, GX 349+2, GX 13+1, GX 3+1, GX 9+1) and built broad-band X-ray spectra from JEM-X1 and IBIS/ISGRI data. For each source, X-ray spectra from different states were fitted with the recently proposed model compTB. The spectra have been fit with a two-compTB model. In all cases the first compTB describes the dominant part of the spectrum that we interpret as thermal Comptonization of soft seed photons (< 1 keV), likely from the accretion disk, by a 3-5 keV corona. In all cases, this component does not evolve much in terms of Comptonization efficiency, with the system converging to thermal equilibrium for increasing accretion rate. The second compTB varies more dramatically spanning from bulk plus thermal Comptonization of blackbody seed photons to the blackbody emission alone. These seed photons (R < 12 km, kT_s > 1 keV), likely from the neutron star and the innermost part of the system, the Transition Layer, are Comptonized by matter in a converging flow. The presence and nature of this second compTB component (be it a pure blackbody or Comptonized) are related to the inner local accretion rate which can influence the transient behaviour of the hard tail: high values of accretion rates correspond to an efficient Bulk Comptonization process (bulk parameter delta > 0) while even higher values of accretion rates suppress the Comptonization, resulting in simple blackbody emission (delta=0).Comment: 12 pages, 10 figures, accepted for publication in A&

HMM-based anomaly interpretation for intelligent robots in Industry 4.0

We apply an anomaly detection method based on Hidden Markov Models and Hellinger distance to a Kairos mobile robot operating in the ICE lab, a research laboratory for Industry 4.0. Two main contributions are proposed: i) a decomposition of the Hellinger distance which allows to identify the causes of anomalous behaviours detected, ii) a graphical user interface that synchronously shows the robot movements in a map and the evolution of the Hellinger distance components, allowing a quick investigation of the causes of the detected anomalies. The tools are applied to a real-world dataset allowing to discover that an anomalous movement of the Kairos robot is caused by a wrong reading of the lidar from a window in the environment

Learning state-variable relationships for improving POMCP performance

We address the problem of learning state-variable relationships across different episodes in Partially Observable Markov Decision Processes (POMDPs) to improve planning performance. Specifically, we focus on Partially Observable Monte Carlo Planning (POMCP) and we represent the acquired knowledge with Markov Random Fields (MRFs). We propose three different methods to compute MRF parameters while the agent acts in the environment. Our tech- niques acquire information from agent action outcomes, and from the belief of the agent, which summarizes the knowledge acquired from observations. We also propose a stopping criterion to deter- mine when the MRF is accurate enough and the learning process can be stopped. Results show that the proposed approach allows to effectively learn state-variable probabilistic constraints and to outperform standard POMCP with no computational overhead