92 research outputs found

    A Spatial Calculus of Wrapped Compartments

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    The Calculus of Wrapped Compartments (CWC) is a recently proposed modelling language for the representation and simulation of biological systems behaviour. Although CWC has no explicit structure modelling a spatial geometry, its compartment labelling feature can be exploited to model various examples of spatial interactions in a natural way. However, specifying large networks of compartments may require a long modelling phase. In this work we present a surface language for CWC that provides basic constructs for modelling spatial interactions. These constructs can be compiled away to obtain a standard CWC model, thus exploiting the existing CWC simulation tool. A case study concerning the modelling of Arbuscular Mychorrizal fungi growth is discussed.Comment: Presented at MeCBIC 201

    Correlating electron trapping and structural defects in Al2O3 thin films deposited by plasma enhanced atomic layer deposition

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    In this article, electron trapping in aluminum oxide (Al2O3) thin films grown by plasma enhanced atomic layer deposition on AlGaN/GaN heterostructures has been studied and a correlation with the presence of oxygen defects in the film has been provided. Capacitance–voltage measurements revealed the occurrence of a negative charge trapping effect upon bias stress, able to fill an amount of charge traps in the bulk Al2O3 in the order of 5 × 1012 cm−2. A structural analysis based on electron energy-loss spectroscopy demonstrated the presence of low-coordinated Al cations in the Al2O3 film, which is an indication of oxygen vacancies, and can explain the electrical behavior of the film. These charge trapping effects were used for achieving thermally stable (up to 100 °C) enhancement mode operation in AlGaN/GaN transistors, by controlling the two-dimensional electron gas depletion

    THE ENVIRONMENTAL IMPACT OF POWER LINES ON BIRDS IN SICILY

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    Electrocution is a serious conservation problem worldwide for a large number of bird species (BEVANGER, 1994, 1998; BIRDLIFE INTERNATIONAL, 2004; PRINSEN et al., 2011). Due to its wide extension, it is necessary to seek methods that optimize the identification of the most dangerous pylons (JANSS and FERRER, 2001; MANOSA, 2001), lines and the highest risk areas (TINTÓ et al., 2010; GUIL et al., 2011). Actually, the data on bird mortality caused by electrocution and collision in Sicily are deficient, however, a preliminary study suggests that the White Stork (Ciconia ciconia L., 1758) is one of the most threatened species inside two Special Protection Areas (SPA) (ZAFARANA and BARBERA, 2016). The project C.L.E.S.A. aims at making a complete checklist of the species at risk, collecting information from published articles and personal reports. Unpublished data were collected through a request for information widely circulated among professional and dabbler ornithologists, local sections of bird conservation ONG and wildlife services. A standard monitoring method was used to collect data, monthly during the entire sampling period. First, we selected different transects randomly, and, subsequently, we counted and removed all the birds found dead. A total of 152 cases were collected from 1996 to 2017, of which 85 caused by electrocution and 67 by collision. The 55.5% of the founded species are considered as “Birds of Community Importance” (included in Annex I of the Council Directive 2009/147/EC on the conservation of wild birds). C. ciconia is the most species killed by electrocution and Phoenicopterus roseus Pallas, 1811 by collision. These preliminary results suggest that this problem, as well as having serious consequences in terms of conservation, could has serious economic repercussions for human societies, as power failures, loss of revenue, necessity of repairs infrastructures and cost of legal compliance (LEHMAN et al., 2007). The monitoring activities of the C.L.E.S.A. volunteers have the purpose of implementing direct conservation actions for endangered species. The synergy between power companies and C.L.E.S.A. will be basic to adopt the measures suggested by the Conference of the Parties in Resolution 7.4 "Electrocution of migratory birds" (BONN, 2002) and the current management plans for SPAs. This partnership will improve the effective field actions in Sicily

    Self-formed LaAlO3/SrTiO3LaAlO_3/SrTiO_3 Micro-Membranes

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    Oxide heterostructures represent a unique playground for triggering the emergence of novel electronic states and for implementing new device concepts. The discovery of 2D conductivity at the LaAlO3/SrTiO3LaAlO_3/SrTiO_3 interface has been linking for over a decade two of the major current research fields in Materials Science: correlated transition-metal-oxide systems and low-dimensional systems. A full merging of these two fields requires nevertheless the realization of LaAlO3/SrTiO3LaAlO_3/SrTiO_3 heterostructures in the form of freestanding membranes. Here we show a completely new method for obtaining oxide hetero-membranes with micrometer lateral dimensions. Unlike traditional thin-film-based techniques developed for semiconductors and recently extended to oxides, the concept we demonstrate does not rely on any sacrificial layer and is based instead on pure strain engineering. We monitor through both real-time and post-deposition analyses, performed at different stages of growth, the strain relaxation mechanism leading to the spontaneous formation of curved hetero-membranes. Detailed transmission electron microscopy investigations show that the membranes are fully epitaxial and that their curvature results in a huge strain gradient, each of the layers showing a mixed compressive/tensile strain state. Electronic devices are fabricated by realizing ad hoc circuits for individual micro-membranes transferred on silicon chips. Our samples exhibit metallic conductivity and electrostatic field effect similar to 2D-electron systems in bulk heterostructures. Our results open a new path for adding oxide functionality into semiconductor electronics, potentially allowing for ultra-low voltage gating of a superconducting transistors, micromechanical control of the 2D electron gas mediated by ferroelectricity and flexoelectricity, and on-chip straintronics.Comment: 8 pages, 4 figure

    Covid-19 And Rheumatic Autoimmune Systemic Diseases: Role of Pre-Existing Lung Involvement and Ongoing Treatments

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    The Covid-19 pandemic may have a deleterious impact on patients with autoimmune systemic diseases (ASD) due to their deep immune-system alterations

    Geographical heterogeneity of clinical and serological phenotypes of systemic sclerosis observed at tertiary referral centres. The experience of the Italian SIR-SPRING registry and review of the world literature

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    Introduction: Systemic sclerosis (SSc) is characterized by a complex etiopathogenesis encompassing both host genetic and environmental -infectious/toxic- factors responsible for altered fibrogenesis and diffuse microangiopathy. A wide spectrum of clinical phenotypes may be observed in patients' populations from different geographical areas. We investigated the prevalence of specific clinical and serological phenotypes in patients with definite SSc enrolled at tertiary referral centres in different Italian geographical macro-areas. The observed findings were compared with those reported in the world literature.Materials and methods: The clinical features of 1538 patients (161 M, 10.5%; mean age 59.8 +/- 26.9 yrs.; mean disease duration 8.9 +/- 7.7 yrs) with definite SSc recruited in 38 tertiary referral centres of the SPRING (Systemic sclerosis Progression INvestiGation Group) registry promoted by Italian Society of Rheumatology (SIR) were obtained and clustered according to Italian geographical macroareas.Results: Patients living in Southern Italy were characterized by more severe clinical and/or serological SSc phenotypes compared to those in Northern and Central Italy; namely, they show increased percentages of diffuse cutaneous SSc, digital ulcers, sicca syndrome, muscle involvement, arthritis, cardiopulmonary symptoms, interstitial lung involvement at HRCT, as well increased prevalence of serum anti-Scl70 autoantibodies. In the same SSc population immunusppressive drugs were frequently employed. The review of the literature underlined the geographical heterogeneity of SSc phenotypes, even if the observed findings are scarcely comparable due to the variability of methodological approaches.Conclusion: The phenotypical differences among SSc patients' subgroups from Italian macro-areas might be correlated to genetic/environmental co-factors, and possibly to a not equally distributed national network of information and healthcare facilities

    Measurement of the Ratio of b Quark Production Cross Sections in Antiproton-Proton Collisions at 630 GeV and 1800 GeV

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    We report a measurement of the ratio of the bottom quark production cross section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom quarks with transverse momenta greater than 10.75 GeV identified through their semileptonic decays and long lifetimes. The measured ratio sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement with next-to-leading order (NLO) quantum chromodynamics (QCD)

    Multiobjective Optimization of Circuit Performances through Solution Ranking and Evolutionary Strategies

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    This work concerns the optimization of circuit performances of a Two Stage Operational Transconductance Amplifier. The problem arises from the circuit design flow which uses simulators when these tools and their inner device models are considered as a black-box. The performance specifications are targets for the optimization and are explored in a multiobjective space. Solution ranking by Pareto dominance criterion leads to more stable multiobjective solutions which is an important consideration from the design point of view. Evolutionary strategies can exploit this solution rank by selection in order to get a set of non-dominated equivalent solutions called Pareto optimal front. [DOI: 10.1685/CSC06138] About DO
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