4,866 research outputs found

    Influence of the halo upon angular distributions for elastic scattering and breakup

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    The angular distributions for elastic scattering and breakup of halo nuclei are analysed using a near-side/far-side decomposition within the framework of the dynamical eikonal approximation. This analysis is performed for 11Be impinging on Pb at 69 MeV/nucleon. These distributions exhibit very similar features. In particular they are both near-side dominated, as expected from Coulomb-dominated reactions. The general shape of these distributions is sensitive mostly to the projectile-target interactions, but is also affected by the extension of the halo. This suggests the elastic scattering not to be affected by a loss of flux towards the breakup channel.Comment: 11 pages, 3 figures, accepted for publication in Phys. Lett.

    The CMCC-INGV Global Ocean Data Assimilation System (CIGODAS)

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    This report summarizes the technical structure and main characteristics of the CMCCINGV Global Ocean Data Assimilation System (CIGODAS) based on a Reduced Order Optimal Interpolation scheme and a coarse resolution Global Ocean Model for the assimilation of temperature and salinity observations. It is intended to be a reference guide for new users who are interested in setting up and running an experiment using this approach and producing estimates of the timevarying, threedimensional state of the global ocean

    Spectral weight redistribution in (LaNiO3)n/(LaMnO3)2 superlattices from optical spectroscopy

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    We have studied the optical properties of four (LaNiO3_3)n_n/(LaMnO3_3)2_2 superlattices (SL) (nn=2, 3, 4, 5) on SrTiO3_3 substrates. We have measured the reflectivity at temperatures from 20 K to 400 K, and extracted the optical conductivity through a fitting procedure based on a Kramers-Kronig consistent Lorentz-Drude model. With increasing LaNiO3_3 thickness, the SLs undergo an insulator-to-metal transition (IMT) that is accompanied by the transfer of spectral weight from high to low frequency. The presence of a broad mid-infrared band, however, shows that the optical conductivity of the (LaNiO3_3)n_n/(LaMnO3_3)2_2 SLs is not a linear combination of the LaMnO3_3 and LaNiO3_3 conductivities. Our observations suggest that interfacial charge transfer leads to an IMT due to a change in valence at the Mn and Ni sites.Comment: Accepted for publication in Phys. Rev. Lett. 5 pages, 5 figure

    Complex delay dynamics on railway networks: from universal laws to realistic modelling

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    Railways are a key infrastructure for any modern country. The reliability and resilience of this peculiar transportation system may be challenged by different shocks such as disruptions, strikes and adverse weather conditions. These events compromise the correct functioning of the system and trigger the spreading of delays into the railway network on a daily basis. Despite their importance, a general theoretical understanding of the underlying causes of these disruptions is still lacking. In this work, we analyse the Italian and German railway networks by leveraging on the train schedules and actual delay data retrieved during the year 2015. We use {these} data to infer simple statistical laws ruling the emergence of localized delays in different areas of the network and we model the spreading of these delays throughout the network by exploiting a framework inspired by epidemic spreading models. Our model offers a fast and easy tool for the preliminary assessment of the {effectiveness of} traffic handling policies, and of the railway {network} criticalities.Comment: 32 pages (with appendix), 28 Figures (with appendix), 2 Table

    Evidence from multivariate morphometric study of the quercus pubescens complex in southeast Italy

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    The name Quercus pubescens s.l. encompasses a complex of deciduous oak taxa with mainly southeastEuropean distribution and a large ecological niche. As the easternmost region of Italy, Apulia is rather isolated from a geographical and physiographical viewpoint and counts the highest number of oak species (10). In the taxonomic and phytosociological literature, the occurrence of several species belonging to the Quercus pubescens collective group is reported for this region. In order to verify if different sets of morphological characters are associated with different taxa, 24 populations of Quercus pubescens s.l. located in different ecological-geographical areas of Apulia were sampled. A total of 367 trees, 4254 leaves and 1120 fruits were collected and morphologically analysed. Overall, 25 morphological characters of oak leaves and fruits were statistically treated using both univariate and multivariate analysis. Nested ANOVA showed that leaves collected from a single tree exhibited a degree of morphological variability higher than that observed when comparing leaves coming from different trees of the same population and from different trees of different populations as well. Almost all the morphological characters analysed exhibited a continuous trend of variation so that none of them can be used as a character to discriminate between populations. Only leaf and fruit “size” and fruit petiole length emerged as slightly discriminating characters. Our results suggest that it is unlikely that more than one species belonging to the Quercus pubescens complex occurs in the Apulia region. Comparison between the Apulian populations and a genetically pure Q. pubescens population coming from a different area (the Molise region) strengthened the assumption as to the existence of a single species that can provisionally be classified under the name of Q. pubescens s.

    Phase diagram and optical conductivity of La1.8-xEu0.2SrxCuO4

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    La1.8-xEu0.2SrxCuO4 (LESCO) is the member of the 214 family which exhibits the largest intervals among the structural, charge ordering (CO), magnetic, and superconducting transition temperatures. By using new dc transport measurements and data in the literature we construct the phase diagram of LESCO between x = 0.8 and 0.20. This phase diagram has been further probed in ac, by measuring the optical conductivity {\sigma}1({\omega}) of three single crystals with x = 0.11, 0.125, and 0.16 between 10 and 300 K in order to associate the extra-Drude peaks often observed in the 214 family with a given phase. The far-infrared peak we detect in underdoped LESCO is the hardest among them, survives up to room temperature and is associated with charge localization rather than with ordering. At the CO transition for the commensurate doping x = 0.125 instead the extra-Drude peak hardens and a pseudogap opens in {\sigma}1({\omega}), approximately as wide as the maximum superconducting gap of LSCO.Comment: 6 pages, 6 figure

    Global ocean re-analyses for climate applications

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    One of the main objectives of the global ocean modelling activities at Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC) is the production of global ocean re-analyses over multidecadal periods to reconstruct the state of the ocean and the large scale cir- culation over the recent past. The re-analyses are used for climate applications and for the assessment of the benefits of assimilating ocean observations on seasonal and longer predictions. Here we present the main characteristics of an optimal interpola- tion based assimilation system used to produce a set of global ocean re-analyses validated against a set of high quality in situ observa- tions and independent data. Differences among the experiments of the set are analyzed in terms of improvements in the method used to assimilate the data and the quality of observations them- selves. For example, the integrated ocean heat content, which can be taken as an indicator of climate changes, is examined to detect possible sources of uncertainty of its long-term changes. Global and basin scale upper ocean heat content exhibits warming trends over the last few decades that still depend in a significant way on the assimilated observations and the formulation of the background covariances. However, all the re-analyses show a global warming trend of the oceanic uppermost 700 m over the last five decades that falls within the range of the most recent observation-based estimates. The largest discrepancies between our estimates and observational based ones are confined in the upwelling regions of the PacificandAtlanticOceans.Finally,theresultsshow that the climatological heat and salt transports as a function of latitude also fall within the range of the estimates based on observations and atmospheric re-analyses

    A geobotanical survey on acidophilous grasslands in the Abruzzo, Lazio and Molise National Park (Central Italy)

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    The acidophilous grasslands of the south-eastern part of the Abruzzo, Lazio and Molise National Park was studied by the phytosociological method and analyzed from a synecological viewpoint with the help of soil analysis. Four clusters of relevés resulted from the numerical classification. Syntaxonomically they were ascribed to the following associations: Poo violaceae-Nardetum strictae, Potentillo rigoanae-Festucetum paniculatae, Nardo strictae-Brachypodietum genuensis and Potentillo rigoanae-Brachypodietum genuensis. Since the original proposal of all the syntaxa identified in the present study were affected by nomenclatural mistakes, they were corrected in accordance with the rules of ICPN. The occurrence of Anthoxanto-Brachypodietum in central Apennines, is excluded since this association falls in syntaxonomical synonymy with Potentillo-Brachypodietum. The synecological analysis proved that the distribution of the different communities identified within the study area to be correlated with topographic, geomorphological and soil factors. Among these latter, the ratio H+/basic cations, pH behave as the most influencing parameters in the distribution of the communities identified
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