874 research outputs found

    Observed modes of sea surface temperature variability in the South Pacific region

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    The South Pacific (SP) region exerts large control on the climate of the Southern Hemisphere at many times scales. This paper identifies the main modes of interannual sea surface temperature (SST) variability in the SP which consist of a tropical-driven mode related to a horseshoe structure of positive/negative SST anomalies within midlatitudes and highly correlated to ENSO and Interdecadal Pacific Oscillation (IPO) variability, and another mode mostly confined to extratropical latitudes which is characterized by zonal propagation of SST anomalies within the South Pacific Gyre. Both modes are associated with temperature and rainfall anomalies over the continental regions of the Southern Hemisphere. Besides the leading mode which is related to well known warmer/cooler and drier/moister conditions due to its relationship with ENSO and the IPO, an inspection of the extratropical mode indicates that it is associated with distinct patterns of sea level pressure and surface temperature advection. These relationships are used here as plausible and partial explanations to the observed warming trend observed within the Southern Hemisphere during the last decades.The authors would like to thank Scott Power for his comments on an earlier version of the manuscript and the two anonymous reviewers whose suggestions led to a substantial improvement of the paper. This study was supported by Grants UBACyT-20020100100803, UBACyT-20020120300051, PIP-11220120100586 and the SPECS (GA 308378) EU-funded Project. JG-S was partially supported by the H2020-funded MSCA-IF-EF DPETNA project (GA No. 655339). The authors acknowledge the Red Española de Supercomputación (RES) and PRACE for awarding access to MareNostrum 3 at the Barcelona Supercomputing Center through the HiResClim project. The support of Virginie Guémas and Oriol Mula-Valls at the Barcelona Supercomputing Center is warmly appreciated.Peer ReviewedPostprint (author's final draft

    Pump-and-probe optical transmission phase shift as a quantitative probe of the Bogoliubov dispersion relation in a nonlinear channel waveguide

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    We theoretically investigate the dispersion relation of small-amplitude optical waves superimposing upon a beam of polarized monochromatic light propagating along a single-mode channel waveguide characterized by an instantaneous and spatially local Kerr nonlinearity. These small luminous fluctuations propagate along the waveguide as Bogoliubov elementary excitations on top of a one-dimensional dilute Bose quantum fluid evolve in time. They consequently display a strongly renormalized dispersion law, of Bogoliubov type. Analytical and numerical results are found in both the absence and the presence of one- and two-photon losses. Silicon and silicon-nitride waveguides are used as examples. We finally propose an experiment to measure this Bogoliubov dispersion relation, based on a stimulated four-wave mixing and interference spectroscopy techniques.Comment: 17 pages, 7 figure

    Relationship between Exotic Plant Species Richness, Native Vegetation and Climate in Forest Ecosystems of Chile

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    In this chapter, we evaluated how native species cover, native species richness, and foliage periodicity of forests are related to exotic species richness in different forest ecosystems distributed through the Mediterranean-type and temperate climate regions of Chile. We compiled published and unpublished data on Chilean vegetation (mainly phytosociological studies) located between 30º and 41º S in which plant species composition and abundance (percentage of cover) per plot was evaluated and published. When all forests were analysed together, we found that exotic species richness was not significantly related to native species richness; it was negatively related to native species cover in both Mediterranean and temperate climatic regions and was greater in deciduous than evergreen forests, although only in the temperate region. In an analysis considering separately every forest type, we observed that only in 50% of these communities, exotic species richness was negatively related to native species cover. Furthermore, in 25% of forest types, exotic species richness was negatively related to native species richness, and in only one forest type, this relationship was positive. Our results suggest that native species produce some resistance against invasion of exotic plants, but this effect may depend on climate and forest type

    Un sondeig a la via Augusta al terme municipal de la Salzadella (el Baix Maestrat, Castelló).

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    En este artículo presentamos los resultados de una excavación realizada en la vía Augusta cerca de la población de la Salzadella (Castellón), situada entre las mansiones de Intibili e Ildum. Aunque la calzada había sido destruida parcialmente por la excavación de una acequia, se pudo descubrir un tramo de su mitad este. Palabras clave: Calzadas romanas, vía Augusta, La Salzadella. This paper presents the results of an excavation in the Via Augusta near the town of la Salzadella (Castellón) located between the mansions of Intibili and Ildum. Although the road was partially destroyed in the excavation of a ditch, a section of its eastern half it was discovered

    BRAHMS Overview

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    A brief review of BRAHMS measurements of bulk particle production in RHIC Au+Au collisions at sNN=200GeV\sqrt{s_{NN}}=200GeV is presented, together with some discussion of baryon number transport. Intermediate pTp_{T} measurements in different collision systems (Au+Au, d+Au and p+p) are also discussed in the context of jet quenching and saturation of the gluon density in Au ions at RHIC energies. This report also includes preliminary results for identified particles at forward rapidities in d+Au and Au+Au collisions.Comment: 8 pages 6 figures, Invited plenary talk at 5th International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPAQGP 2005), Salt Lake City, Kolkata, India, 8-12 Feb 200

    Novena campanya d'excavacions a la ciutat romana de Lesera

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    En aquesta nota presentem un avanç dels resultats de la campanya d'excavacions de 2015 realitzada a la ciutat romana de Lesera, que fou finançada per la Mancomunitat Comarcal dels Ports en el marc del Pla Formatiu d'auxiliars en Arqueologia del Taller d'Ocupació, i es desenvolupà de manera discontínua entre els dies 16 de març i 22 de juliol. Les excavacions es feren en el marc de les pràctiques dels alumnes d'aquest taller1. L'actuació consistí en la continuació dels treballs començats en els anys 2008-2009 als sondeigs 6 i 8 (Arasa 2009a), situats al sector N de la plataforma inferior del jaciment. Les conclusions que exposem tenen un caràcter provisional, atés que encara no ha finalitzat l'estudi dels materials recuperats
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