2,635 research outputs found

    The complexity of the embeddability relation between torsion-free abelian groups of uncountable size

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    We prove that for every uncountable cardinal κ\kappa such that κ<κ=κ\kappa^{<\kappa}=\kappa, the quasi-order of embeddability on the κ\kappa-space of κ\kappa-sized graphs Borel reduces to the embeddability on the κ\kappa-space of κ\kappa-sized torsion-free abelian groups. Then we use the same techniques to prove that the former Borel reduces to the embeddability on the κ\kappa-space of κ\kappa-sized RR-modules, for every S\mathbb{S}-cotorsion-free ring RR of cardinality less than the continuum. As a consequence we get that all the previous are complete Σ11\boldsymbol{\Sigma}^1_1 quasi-orders.Comment: 14 pages, final versio

    Universality of group embeddability

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    Working in the framework of Borel reducibility, we study various notions of embeddability between groups. We prove that the embeddability between countable groups, the topological embeddability between (discrete) Polish groups, and the isometric embeddability between separable groups with a bounded bi-invariant complete metric are all invariantly universal analytic quasi-orders. This strengthens some results from [Wil14] and [FLR09].Comment: Minor corrections. 15 pages, submitte

    Although there is little truth behind the ‘Godfather’ stereotype, mafia infiltration remains a serious problem in Italian politics

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    From the Godfather to Tony Soprano, the idea of the Mafia continues to have a special place in Western popular culture. Francesco Calderoni argues that despite the popularity of Mafia stereotypes, relatively little research has been carried out on the actual link between organised crime and politics in Italy. By mapping the areas of the country which have the highest Mafia presence, he illustrates the extent to which the problem has spread beyond the traditional hotspots of Mafia activity in Naples, Western Sicily, Northern Campania and Southern Calabria

    Predicting atomic dopant solvation in helium clusters: the MgHen_n case

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    We present a quantum Monte Carlo study of the solvation and spectroscopic properties of the Mg doped helium clusters MgHen_n with n=250n=2-50. Three high level (MP4, CCSD(T) and CCSDT) MgHe interaction potentials have been used to study the sensitivity of the dopant location on the shape of the pair interaction. Despite the similar MgHe well depth, the pair distribution functions obtained in the diffusion Monte Carlo simulations markedly differ for the three pair potentials, therefore indicating different solubility properties for Mg in Hen_n. Moreover, we found interesting size effects for the behavior of the Mg impurity. As a sensitive probe of the solvation properties, the Mg excitation spectra have been simulated for various cluster sizes and compared with the available experimental results. The interaction between the excited 1^1P Mg atom and the He moiety has been approximated using the Diatomics-in-Molecules method and the two excited 1Π^1\Pi and 1Σ^1\Sigma MgHe potentials. The shape of the simulated MgHe50_{50} spectra show a substantial dependency on the location of the Mg impurity, and hence on the MgHe pair interaction employed. To unravel the dependency of the solvation behavior on the shape of the computed potentials, exact Density Functional Theory has been adapted to the case of doped Hen_n and various energy distributions have been computed. The results indicate the shape of the repulsive part of the MgHe potential as an important cause of the different behaviours

    Up to date on the use of triptans for child and adolescent migraine: “the state of the art”

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    The introduction of triptans, in the early 1990s, has improved the therapy for acute migraine attack, offering a new quality of life for those patients who suffer from this disabling neurological disorder. Epidemiological data point out that about 10% of school–age children suffer from migraine, with a progressive increase in incidence and prevalence up to the threshold of adulthood. The increase in extent and prevalence of migraine from the years of growth stresses the importance of the application and adjustment of ad hoc therapeutic (either pharmacological or not) and diagnostic measures. Indeed, the peculiar neurobiological and psychological aspects which are typical of an “evolving” organism preclude the use, by simple “transposition” or “proportion”, of the knowledge acquired from adult–targeted studies. That requires the implementation of studies to analyze the specific responses of children and adolescents to the triptans. To date, the studies on such issues are absolutely insufficient to draw definitive conclusions and indications for the use of triptans for child and adolescent migraineurs

    Uncountable structures are not classifiable up to bi-embeddability

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    Answering some of the main questions from [MR13], we show that whenever κ\kappa is a cardinal satisfying \kappa^{ \omega, then the embeddability relation between κ\kappa-sized structures is strongly invariantly universal, and hence complete for (κ\kappa-)analytic quasi-orders. We also prove that in the above result we can further restrict our attention to various natural classes of structures, including (generalized) trees, graphs, or groups. This fully generalizes to the uncountable case the main results of [LR05,FMR11,Wil14,CMR17].Comment: 37 pages, submitted. arXiv admin note: text overlap with arXiv:1112.035

    Metacognition and headache: which Is the role in childhood and adolescence?

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    Headache, in particular migraine, is one of the most frequent neurological symptoms in children and adolescents and it affects about 60% of children and adolescents all over the world. Headache can affect several areas of child’s functioning, such as school, physical activities, peer, and family relationship. The global and severe burden of this disease requires a multidisciplinary strategy and an effective treatment addressed all of the patient’s needs and based on cutting-edge scientific research. In recent years, research has focused on cognitive factors specifically in functions called metacognitive processes. Metacognition can be defined as the knowledge, beliefs, and cognitive processes involved in monitoring, control, and assessment of cognition. Metacognition seems to be closely related to the ability of theory of mind, the ability to infer, and reason about the mental states of other people in order to predict and explain own behavior. Recent studies found a relationship between metacognitive skills and anxiety, depression, motivation, academic performance, human social interactions, and stress symptoms. This relationship is very interesting for headache treatment, because these factors are the most commonly reported triggers in this disorder and there is a high comorbidity with anxiety and depression in children and adolescents with headache. So, headache and these comorbidities, in particular anxiety and depression, may have in common persistent and maladaptive patterns of thinking which are related to maladaptive metacognitive beliefs. Further research should assess metacognitive processes of children and adolescents with headache in order to increase their ability to control their own cognitive processes and consequently monitor factors which may trigger the attacks

    In memory of Ettore Grimaldi

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    Ettore Grimaldi (1934-2015) was one of the brightest and active ichthyologists in Italy. He was a man of great enthusiasm, boundless energy and great curiosity. He was a person with an open mind. He originally visited the Institute of Pallanza in June 1957 as a master student at the Faculty of Veterinary Medicine, University of Milan. He was formally called back by the Director Vittorio Tonolli, as a research assistant in 1962..

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    An anonymous inter-network routing protocol for the Internet of Things

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    With the diffusion of the Internet of Things (IoT), computing is becoming increasingly pervasive, and different heterogeneous networks are integrated into larger systems. However, as different networks managed by different parties and with different security requirements are interconnected, security becomes a primary concern. IoT nodes, in particular, are often deployed “in the open”, where an attacker can gain physical access to the device. As nodes can be deployed in unsurveilled or even hostile settings, it is crucial to avoid escalation from successful attacks on a single node to the whole network, and from there to other connected networks. It is therefore necessary to secure the communication within IoT networks, and in particular, maintain context information private, including the network topology and the location and identity of the nodes. In this paper, we propose a protocol achieving anonymous routing between different interconnected networks, designed for the Internet of Things and based on the spatial Bloom filter (SBF) data structure. The protocol enables private communication between the nodes through the use of anonymous identifiers, which hide their location and identity within the network. As routing information is encrypted using a homomorphic encryption scheme, and computed only in the encrypted domain, the proposed routing strategy preserves context privacy, preventing adversaries from learning the network structure and topology. This, in turn, significantly reduces their ability to gain valuable network information from a successful attacks on a single node of the network, and reduces the potential for attack escalation
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