4,472 research outputs found

    Gravitating superconducting strings with timelike or spacelike currents

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    We construct gravitating superconducting string solutions of the U(1)_{local} x U(1)_{global} model solving the coupled system of Einstein and matter field equations numerically. We study the properties of these solutions in dependence on the ratio between the symmetry breaking scale and the Planck mass. Using the macroscopic stability conditions formulated by Carter, we observe that the coupling to gravity allows for a new stable region that is not present in the flat space-time limit. We match the asymptotic metric to the Kasner metric and show that the relations between the Kasner coefficients and the energy per unit length and tension suggested previously are well fulfilled for symmetry breaking scale much smaller than the Planck mass. We also study the solutions to the geodesic equation in this space-time. While geodesics in the exterior space-time of standard cosmic strings are just straight lines, test particles experience a force in a general Kasner space-time and as such bound orbits are possible.Comment: 16 pages including 14 figure

    Using poverty maps to improve the design of household surveys: the evidence from Tunisia

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    In this paper we aim to propose a new method for improving the design effect of household surveys based on a two-stage design in which the first stage clusters, or Primary Selection Units (PSUs), are stratified along administrative boundaries. Improvement of the design effect can result in more precise survey estimates (smaller standard errors and confidence intervals) or in the reduction of the necessary sample size, i.e. a reduction in the budget needed for a survey. The proposed method is based on the availability of a previously conducted poverty maps, i.e. spatial descriptions of the distribution of per capita consumption expenditures, that are finely disaggregated in small geographic units, such as cities, municipalities, districts or other administrative partitions of a country that are directly linked to PSUs. Such information is then used to select PSUs with systematic sampling by introducing further implicit stratification in the survey design, so as to maximise the improvement of the design effect. Since per capita consumption expenditures estimated at PSU level from the poverty mapping are affected by (small) standard errors, in the paper we also perform a simulation study in order to take into account this addition variability

    Hard real-time performances in multiprocessor-embedded systems using ASMP-Linux

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    Multiprocessor systems, especially those based on multicore or multithreaded processors, and new operating system architectures can satisfy the ever increasing computational requirements of embedded systems.ASMP-LINUX is a modified, high responsiveness, open-source hard real-time operating system for multiprocessorsystems capable of providing high real-time performance while maintaining the code simple and not impacting on theperformances of the rest of the system. Moreover, ASMP-LINUX does not require code changing or application recompiling/relinking.In order to assess the performances of ASMP-LINUX, benchmarks have been performed on several hardware platformsand configurations

    Analytical and numerical seismic assessment of heritage masonry towers

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    Abstract The new Italian building code, published in 2018 [MIT in NTC 2018: D.M. del Ministero delle Infrastrutture e dei trasporti del 17/01/2018. Aggiornamento delle Norme Tecniche per le Costruzioni (in Italian), 2018], explicitly refers to the Italian “Guidelines for the assessment and mitigation of the seismic risk of the cultural heritage” [PCM in DPCM 2011: Direttiva del Presidente del Consiglio dei Ministri per valutazione e riduzione del rischio sismico del patrimonio culturale con riferimento alle norme tecniche per le costruzioni, G.U. n. 47 (in Italian), 2011] as a reliable source of guidance that can be employed for the vulnerability assessment of heritage buildings under seismic loads. According to these guidelines, three evaluation levels are introduced to analyse and assess the seismic capacity of historic masonry structures, namely: (1) simplified global static analyses; (2) kinematic analyses based on local collapse mechanisms, (3) detailed global analyses. Because of the complexity and the large variety of existing masonry typologies, which makes it particularly problematic to adopt a unique procedure for all existing structures, the guidelines provide different simplified analysis approaches for different structural configurations, e.g. churches, palaces, towers. Among the existing typologies of masonry structures there considered, this work aims to deepen validity, effectiveness and scope of application of the Italian guidelines with respect to heritage masonry towers. The three evaluation levels proposed by the guidelines are here compared by discussing the seismic risk assessment of a representative masonry tower: the Cugnanesi tower located in San Gimignano (Italy). The results show that global failure modes due to local stress concentrations cannot be identified if only simplified static and kinematic analyses are performed. Detailed global analyses are in fact generally needed for a reliable prediction of the seismic performance of such structures.</jats:p

    Analytical and numerical seismic assessment of heritage masonry towers

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    Multiple algebraisations of an elliptic Calogero-Sutherland model

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    Recently, Gomez-Ullate et al. (1) have studied a particular N-particle quantum problem with an elliptic function potential supplemented by an external field. They have shown that the Hamiltonian operator preserves a finite dimensional space of functions and as such is quasi exactly solvable (QES). In this paper we show that other types of invariant function spaces exist, which are in close relation to the algebraic properties of the elliptic functions. Accordingly, series of new algebraic eigenfunctions can be constructed.Comment: 9 Revtex pages, 3 PS-figures; Summary, abstract and conclusions extende

    Charged State of a Spherical Plasma in Vacuum

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    The stationary state of a spherically symmetric plasma configuration is investigated in the limit of immobile ions and weak collisions. Configurations with small radii are positively charged as a significant fraction of the electron population evaporates during the equilibration process, leaving behind an electron distribution function with an energy cutoff. Such charged plasma configurations are of interest for the study of Coulomb explosions and ion acceleration from small clusters irradiated by ultraintense laser pulses and for the investigation of ion bunches propagation in a plasma

    Enhanced copy number variants detection from whole-exome sequencing data using EXCAVATOR2

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    Copy Number Variants (CNVs) are structural rear- rangements contributing to phenotypic variation that have been proved to be associated with many dis- ease states. Over the last years, the identification of CNVs from whole-exome sequencing (WES) data has become a common practice for research and clinical purpose and, consequently, the demand for more and more efficient and accurate methods has increased. In this paper, we demonstrate that more than 30% of WES data map outside the targeted re- gions and that these reads, usually discarded, can be exploited to enhance the identification of CNVs from WES experiments. Here, we present EXCAVATOR2, the first read count based tool that exploits all the reads produced by WES experiments to detect CNVs with a genome-wide resolution. To evaluate the per- formance of our novel tool we use it for analysing two WES data sets, a population data set sequenced by the 1000 Genomes Project and a tumor data set made of bladder cancer samples. The results obtained from these analyses demonstrate that EXCAVATOR2 out- performs other four state-of-the-art methods and that our combined approach enlarge the spectrum of detectable CNVs from WES data with an unprece- dented resolution

    Outpatient satisfaction during pharmacotherapy followup

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    This study aimed to investigate the satisfaction of patients with uncontrolled hypertension referred for pharmacotherapy followup. A cross-sectional study by semi-structured interview was used. The sample comprised patients undergoing pharmacotherapy followup, patients who had discontinued pharmacotherapy followup and patients who had not kept the appointments. A total of 80 (76.9 %) out of 104 patients registered were contacted. The majority of patients undergoing pharmacotherapy followup (91.1 %) were fully satisfied with the pharmacists' care given, their relationship with them (94.9 %), the manner in which their therapy was conducted (99.2 %) and the environment where it was carried out (85.3 %). The reasons for non-attendance were mostly forgetting the date, illness on the appointment day and other arrangements on the same day. Interestingly, all of these patients were completely satisfied with the pharmacists' care given. The satisfaction of patients with the pharmaceutical care is high among patients that have continuous followup, but a relevant proportion discontinued followup. Newer approaches to keep these patients under followup are necessary.Colegio de Farmacéuticos de la Provincia de Buenos Aire
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