136 research outputs found

    Optical/NIR stellar absorption and emission-line indices from luminous infrared galaxies

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    We analyze a set of optical-to-near-infrared long-slit nuclear spectra of 16 infrared-luminous spiral galaxies. All of the studied sources present H2_2 emission, which reflects the star-forming nature of our sample, and they clearly display H I emission lines in the optical. Their continua contain many strong stellar absorption lines, with the most common features due to Ca I, Ca II, Fe I, Na I, Mg I, in addition to prominent absorption bands of TiO, VO, ZrO, CN and CO. We report a homogeneous set of equivalent width (EW) measurements for 45 indices, from optical to NIR species for the 16 star-forming galaxies as well as for 19 early type galaxies where we collected the data from the literature. This selected set of emission and absorption-feature measurements can be used to test predictions of the forthcoming generations of stellar population models. We find correlations among the different absorption features and propose here correlations between optical and NIR indices, as well as among different NIR indices, and compare them with model predictions. While for the optical absorption features the models consistently agree with the observations,the NIR indices are much harder to interpret. For early-type spirals the measurements agree roughly with the models, while for star-forming objects they fail to predict the strengths of these indices.Comment: accepted for publication in MNRA

    Two-neutron transfer in the 6 He + 120 Sn reaction

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    A large yield of α particles produced in the 120 Sn ( 6 He , α ) reaction was measured at 20.3-, 22.2-, 22.4-, and 24.5-MeV bombarding energies. The α particles are distributed over a broad energy range in the vicinity and below the elastic scattering 6 He peak. Energy integrated α -particle cross sections have been obtained at Ξ lab = 36 ∘ , 40 ∘ , and 60 ∘ . The α energy distributions have been analyzed at a fixed laboratory angle ( ≈ 60 ∘ ) in terms of the reaction Q value, considering the 2 n -transfer reaction kinematics 120 Sn ( 6 He , α ) 122 Sn . A kinematical analysis of the Q -value distribution shows that the recoil system 120 Sn + 2 n is formed in highly excited states in the continuum, at increasing excitation energies as the bombarding energy increases. It is shown that by using Brink's formula, the excitation energy depends on the transferred angular momentum following a linear relation with the square of the angular momentum, indicating that some kind of dinuclear rotating system is formed after the reaction.Conselho Nacional de Desenvolvimento CientĂ­fico e TecnolĂłgico-CNPq/MCTI de Brasil y Fundação de Amparo Ă  Pesquisa do Estado de SĂŁo Paulo. Brasil–FAPESP. 2013/22100-7 y 2014/19666-1VI Plan Propio de InvestigaciĂłn de la Universidad de Sevilla (2017-2018

    Experimental study of 6He + 9Be elastic scattering at low energies

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    New data for the H6e+9Be reaction at Elab=16.2 and 21.3 MeV have been taken and analyzed. The effect of the collective couplings to the excited states of the target has been studied by means of coupled-channels calculations, using a double-folding potential for the bare interaction between the colliding nuclei, supplemented with a phenomenological imaginary part of Woods-Saxon type. In addition, three- and four-body continuum-discretized coupled-channels calculations have been performed to investigate the effect of the projectile breakup on the elastic scattering. Both effects, the coupling to target and projectile excited states, are found to affect significantly the elastic scattering. The trivial local polarization potential extracted from the continuum-discretized coupled-channels calculations indicates that continuum couplings produce a repulsive real part and a long-range imaginary part in the projectile-target interaction.Junta de AndalucíaMinisterio de Ciencia e Innovación (España) FPA2009-07653 PCI2006-A7-0654Programa Consolider-Ingenio 2010 CSD2007-0004

    Hyaluronic acid hydrogels reinforced with laser spun bioactive glass micro- and nanofibres doped with lithium

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    The repair of articular cartilage lesions in weight-bearing joints remains as a significant challenge due to the low regenerative capacity of this tissue. Hydrogels are candidates to repair lesions as they have similar properties to cartilage extracellular matrix but they are unable to meet the mechanical and biological requirements for a successful outcome. Here, we reinforce hyaluronic acid (HA) hydrogels with 13-93-lithium bioactive glass micro- and nanofibres produced by laser spinning. The glass fibres are a reinforcement filler and a platform for the delivery of therapeutic lithium-ions. The elastic modulus of the composites is more than three times higher than in HA hydrogels. Modelling of the reinforcement corroborates the experimental results. ATDC5 chondrogenic cells seeded on the composites are viable and more proliferation occurs on the hydrogels containing fibres than in HA hydrogels alone. Furthermore, the chondrogenic behavior on HA constructs with fibres containing lithium is more marked than in hydrogels with no-lithium fibres.Xunta de Galicia | Ref. ED431B 2016/042Xunta de Galicia | Ref. POS-A/2013/161Xunta de Galicia | Ref. ED481D 2017/010Xunta de Galicia | Ref. ED481B 2016/047-

    Experimental study of He6+Be9 elastic scattering at low energies

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    New data for the He6+Be9 reaction at Elab=16.2 and 21.3 MeV have been taken and analyzed. The effect of the collective couplings to the excited states of the target has been studied by means of coupled-channels calculations, using a double-folding potential for the bare interaction between the colliding nuclei, supplemented with a phenomenological imaginary part of Woods-Saxon type. In addition, three- and four-body continuum-discretized coupled-channels calculations have been performed to investigate the effect of the projectile breakup on the elastic scattering. Both effects, the coupling to target and projectile excited states, are found to affect significantly the elastic scattering. The trivial local polarization potential extracted from the continuum-discretized coupled-channels calculations indicates that continuum couplings produce a repulsive real part and a long-range imaginary part in the projectile-target interaction. © 2011 American Physical Society.This work has been partially supported by the Spanish Ministerio de Ciencia e InnovacionŽ under Projects FPA2009-07653 and PCI2006-A7-0654 and by the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042).Peer Reviewe

    Portuguese emigration to Angola (2000-2015): Strengthening a specific postcolonial relationship in a new global framework?

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    Outflows to the Portuguese-speaking countries, although not dominant, played an important role in the growth of Portuguese emigration during the economic recession and austerity period, between 2010 and 2016. This chapter examines this migration process, considering that contemporary migration from Portugal to Angola is an example of reverse post-colonial migration within the framework of North-South movements. It presents the historical and socio-demographic background of Angola and some theoretical insights on the issue of North-South migration. The analyses of the migration process and the emigrants’ profiles rely in statistics and academic literature but especially on data gathered in a direct survey. Attention is given to indicators of integration, relations with Portugal and the post-colonial nature of the process. The profile of Portuguese in Angola shows an overrepresentation of highly skilled males over 35 years old, which migrated for professional reasons and sustain relations with Portugal through diverse transnational practices. This supports explanations for the emergence of North-South migration by appeal to economic expansion associated to the increasing insertion of several developing countries into global networks. However, the analysis fails to back up the hypothesis that Portuguese emigration to Angola is a form of reverse post-colonial migration based in ancestral return.info:eu-repo/semantics/publishedVersio

    Mediterranean-climate streams and rivers: geographically separated but ecologically comparable freshwater systems

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    Streams and rivers in mediterranean-climate regions (med-rivers in med-regions) are ecologically unique, with flow regimes reflecting precipitation patterns. Although timing of drying and flooding is predictable, seasonal and annual intensity of these events is not. Sequential flooding and drying, coupled with anthropogenic influences make these med-rivers among the most stressed riverine habitat worldwide. Med-rivers are hotspots for biodiversity in all med-regions. Species in med-rivers require different, often opposing adaptive mechanisms to survive drought and flood conditions or recover from them. Thus, metacommunities undergo seasonal differences, reflecting cycles of river fragmentation and connectivity, which also affect ecosystem functioning. River conservation and management is challenging, and trade-offs between environmental and human uses are complex, especially under future climate change scenarios. This overview of a Special Issue on med-rivers synthesizes information presented in 21 articles covering the five med-regions worldwide: Mediterranean Basin, coastal California, central Chile, Cape region of South Africa, and southwest and southern Australia. Research programs to increase basic knowledge in less-developed med-regions should be prioritized to achieve increased abilities to better manage med-rivers
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