2,328 research outputs found

    The very faint X-ray binary IGR J17062-6143: a truncated disc, no pulsations, and a possible outflow

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    We present a comprehensive X-ray study of the neutron star low-mass X-ray binary IGR J17062-6143, which has been accreting at low luminosities since its discovery in 2006. Analysing NuSTAR, XMM–Newton, and Swift observations, we investigate the very faint nature of this source through three approaches: modelling the relativistic reflection spectrum to constrain the accretion geometry, performing high-resolution X-ray spectroscopy to search for an outflow, and searching for the recently reported millisecond X-ray pulsations. We find a strongly truncated accretion disc at 77+22−18 gravitational radii (∼164 km) assuming a high inclination, although a low inclination and a disc extending to the neutron star cannot be excluded. The high-resolution spectroscopy reveals evidence for oxygen-rich circumbinary material, possibly resulting from a blueshifted, collisionally ionized outflow. Finally, we do not detect any pulsations. We discuss these results in the broader context of possible explanations for the persistent faint nature of weakly accreting neutron stars. The results are consistent with both an ultra-compact binary orbit and a magnetically truncated accretion flow, although both cannot be unambiguously inferred. We also discuss the nature of the donor star and conclude that it is likely a CO or O–Ne–Mg white dwarf, consistent with recent multiwavelength modelling

    Population genetic structure and colonization sequence of Drosophila subobscura in the Canaries and Madeira Atlantic islands as inferred by autosomal, sex-linked and mtDNA traits

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    The genetic structure In Atlantic Islands and continental populations of Drosophila subobscura has been studied using autosomal and sex-linked allozymes and ml tochondrial DNA (mtDNA) haplotypes. From the data it Is deduced that whereas the Canary Islands have long been isolated, the neighboring island of Madeira has been subjected to continuous migration from the mainland. In addition, sex-linked allo zymes and mtDNA data show a large divergence between the geologically younger western Islands of the Canarian Archipelago and the older central ones, finding strong founder effects In the former. Divergence rates of sex-linked and mltochon drlal genes relative to autosomlc loci several times higher than expected under neutrality have been explained by differential migration between sexes. The Ca narian Archipelago colonization fits in well with a stepping-stone model of a direc tional east-west migration that parallels the geological origin of these Islands.info:eu-repo/semantics/publishedVersio

    Searching for light neutralinos with a displaced vertex at the LHC

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    We study a bino-like light neutralino (χ~10\tilde \chi_1^0) produced at the LHC from the decay of a scalar lepton (e~L\tilde e_L) through the process pp→e~L→eχ~10pp\to \tilde e_{L} \to e\tilde \chi_1^0 in the context of R-parity-violating (RPV) supersymmetry where χ~10\tilde \chi_1^0 is the lightest supersymmetric particle. For small masses and RPV couplings, the neutralino is naturally long-lived and its decay products can be identified as displaced tracks. Following existing searches, we propose a displaced-vertex search strategy for such a light neutralino with a single RPV coupling switched on, λ111′\lambda'_{111}, in the mass range 10\,\mbox{GeV} \lesssim m_{\tilde \chi_1^0}\lesssim 230\,\mbox{GeV}. We perform Monte Carlo simulations and conclude that at the high-luminosity LHC, the proposed search can probe values of λ111′\lambda'_{111} down to two orders of magnitude smaller than current bounds and up to 40 times stronger than projected limits from monolepton searches.Comment: 16 pages, 6 figures; v2: comment added, matches version to be published in JHE

    Electromagnetic Form Factors and Charge Radii of Pseudoscalar and Scalar Mesons: A Comprehensive Contact Interaction Analysis

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    We carry out a comprehensive survey of electromagnetic form factors of all light, heavy and heavy-light ground-state pseudoscalar and scalar mesons. Our analysis is based upon a Schwinger-Dyson equations treatment of a vector ×\times vector contact interaction. It incorporates confinement and ensures axial vector and vector Ward-Takahashi identities are satisfied along with the corresponding corollaries such as the Goldberger-Treiman relations. The algebraic simplicity of the model allows us to compute the form factors at arbitrarily large virtualities of the probing photon momentum squared with relative ease. Wherever possible and insightful, we compare our results for the electromagnetic form factors and the charge radii with those obtained earlier through Schwinger-Dyson equations, lattice and with experimental observations available. We also comment on the scope and shortcomings of the model.Comment: 13 pages, 13 figure

    Structure and evolution of the mitochondrial DNA complete control region in the Drosophila subobscura subgroup

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    The complete A + T-rich region of mitochondrial DNA (mtDNA) has been cloned and sequenced in the species of the Drosophila subobscura subgroup D. subobscura, D. madeirensis and D. guanche. Comparative analysis of these sequences with others already published has identified new sequence motifs that are conserved in Drosophila and other insects. A putative bi-directional promoter and a stop signal are proposed to be involved in the primary mtDNA strand replication of Drosophila. This region strongly resolves relationships of the species included in a phylogenetic analysis, both for closely related species and also at deeper phylogenetic levels when only the left and central domains are taken into account.info:eu-repo/semantics/publishedVersio

    Origin of green clinopyroxene cores of lavas from the garrotxa volcanic field (spain)

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    Volcanism of the Garrotxa area is part of the Neogene volcanism of NE Spain (NE Spain volcanic province, NESVP). This volcanism is a manifestation of the magmatic activity consequence of the rift-type extensional tectonics that affect the eastern margin of Iberia since late Oligocene and that involved the opening of the Valencia trough. Volcanic activity in the NESVP started weakly in the Cadaqués zone 15 Ma ago, (C. Lewis, personal communication), followed by the Empordà (9 to 12 Ma in Alt Empordà, 6 Ma in Baix Empordà), La Selva field (5 to 7 Ma) and the Tordera fault system (2 Ma). Finally, activity took place at the Garrotxa volcanic field (GVF) from 300,000 to 10,000 years ago, with an eruptive episode every 15,000 to 20,000 years approximately (C. Lewis personal communication)

    Caracterización mecánica de materiales compuestos de fabricación aditiva

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    Additive Manufacturing is a novel manufacturing method in which the part is produced layer by layer from a 3D CAD model. In this work, we present the mechanical characterization of Fusion Deposition Modeling (FDM). Composite parts made by a nylon matrix with two kinds of fiber reinforcements: carbon fiber or fiberglass. From the obtained microstructure, we perform a division of the composite part in regions, and individual stiffness matrices are encountered by either using a linear elastic isotropic model, for the case of solid matrix filling, or an orthotropic linear elastic model based on micromechanical results. Then, a volume average stiffness method is employed to perform the characterization of the whole part. The theoretical results are compared with the experimental data, showing good agreement for both cases. This research allows the prediction of the structural behavior of additive manufacturing 2composite parts.La manufactura aditiva es un método de fabricación reciente en el que la pieza se produce capa por capa a partir de un modelo CAD 3D. En este trabajo, presentamos la caracterización mecánica del Fusion Deposition Modeling (FDM) aplicada a partes compuestas hechas por una matriz de nailon con dos tipos de refuerzos de fibra: fibra de carbono o fibra de vidrio. A partir de la microestructura obtenida, se realiza una división de la parte compuesta en regiones, y se encuentran matrices de rigidez individuales utilizando un modelo isotrópico elástico lineal, para el caso de relleno de matriz sólida, o un modelo elástico ortotrópico lineal basado en resultados micromecánicos. Luego, se emplea un método de rigidez promedio de volumen para realizar la caracterización de la parte completa. Los resultados teóricos se comparan con los datos experimentales, mostrando una buena concordancia en ambos casos. Esta investigación permite la predicción del comportamiento estructural de las piezas compuestas de fabricación aditiva

    UniHI 7: an enhanced database for retrieval and interactive analysis of human molecular interaction networks.

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    Unified Human Interactome (UniHI) (http://www.unihi.org) is a database for retrieval, analysis and visualization of human molecular interaction networks. Its primary aim is to provide a comprehensive and easy-to-use platform for network-based investigations to a wide community of researchers in biology and medicine. Here, we describe a major update (version 7) of the database previously featured in NAR Database Issue. UniHI 7 currently includes almost 350,000 molecular interactions between genes, proteins and drugs, as well as numerous other types of data such as gene expression and functional annotation. Multiple options for interactive filtering and highlighting of proteins can be employed to obtain more reliable and specific network structures. Expression and other genomic data can be uploaded by the user to examine local network structures. Additional built-in tools enable ready identification of known drug targets, as well as of biological processes, phenotypes and pathways enriched with network proteins. A distinctive feature of UniHI 7 is its user-friendly interface designed to be utilized in an intuitive manner, enabling researchers less acquainted with network analysis to perform state-of-the-art network-based investigations
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