Natural Quintessence in String Theory

We introduce a natural model of quintessence in string theory where the light rolling scalar is radiatively stable and couples to Standard Model matter with weaker-than- Planckian strength. The model is embedded in an anisotropic type IIB compactification with two exponentially large extra dimensions and TeV-scale gravity. The bulk turns out to be nearly supersymmetric since the scale of the gravitino mass is of the order of the observed value of the cosmological constant. The quintessence field is a modulus parameterising the size of an internal four-cycle which naturally develops a potential of the order (gravitino mass)^4, leading to a small dark energy scale without tunings. The mass of the quintessence field is also radiatively stable since it is protected by supersymmetry in the bulk. Moreover, this light scalar couples to ordinary matter via its mixing with the volume mode. Due to the fact that the quintessence field is a flat direction at leading order, this mixing is very small, resulting in a suppressed coupling to Standard Model particles which avoids stringent fifth-force constraints. On the other hand, if dark matter is realised in terms of Kaluza-Klein states, unsuppressed couplings between dark energy and dark matter can emerge, leading to a scenario of coupled quintessence within string theory. We study the dynamics of quintessence in our set-up, showing that its main features make it compatible with observations.Comment: 26 page

Activation Analysis for a He/LiPb dual Coolant Blanket for DEMO Reactor

The objective of the Spanish national project TECNO_FUS is to generate a conceptual design of a DCLL (Dual-Coolant Lithium-Lead) blanket for the DEMO fusion reactor. The dually-cooled breeding zone is composed of He/Pb-15.7 6Li and SiC as liquid metal flow channel inserts. Structural materials are ferritic-martensitic steel (Eurofer-97) for the blanket and austenitic steel (316LN) for the Vacuum Vessel (VV). The goal of this work is to analyze the radioactive waste production by the neutron-induced activation and the back-end of the blanket and the VV (SS316LN) materials (Eurofer, SiC, LiPb, and SS316LN). Furthermore, the radioactive waste production in the cryostat (SS316LN) and the bioshielding (concrete) has been estimated. Following the current approach to the back-end of the materials in fusion facilities, the radioactive waste has been subdivided according to the activity-level classification (EW, exempted waste, LILW, low and intermediate level waste, and HLW, high level waste) and according to the radiological complexity of operations (handling and cooling). The activation calculations have been carried out with the ACAB code

Andragogia do empreendedorismo

O relatório de atividade profissional intitulado como inovação na andragogia do empreendedorismo formula uma postura perante a situação empresarial portuguesa no sentido de contribuir para a formação profissional de adultos enquanto agentes potenciais empreendedores, permitindo despertar as capacidades, conhecimentos e atitudes dos que pretendem seguir o ensino e a formação empreendedora. A justificação do tema demonstra o interesse cada vez maior pelo empreendedorismo, como caminho que se faz e o agente se torna um ator transformador da realidade. O reflexo desta posição é dado pelas notícias que se espelham no noticiário económico e que demonstram a vitalidade das pessoas que não adormecem. O trabalho de anos feito de pequenas construções através do ensino e na divulgação de metodologias na andragogia sempre renovada, permite ajuizar que o campo é vasto e merece ser aprofundado. As jornadas pedagógicas descritas, o “spin-off” criado e o edifício daí resultante, encorajam todos aqueles que querem continuar e a lutar pela formação profissional e, pelo empreendedorismo em particular. Potencialmente cada formando pode ser um potencial empreendedor

Perturbative Charged Rotating 5D Einstein-Maxwell Black Holes

We present perturbative charged rotating 5D Einstein-Maxwell black holes with spherical horizon topology. The electric charge Q is the perturbative parameter, the perturbations being performed up to 4th order. The expressions for the relevant physical properties of these black holes are given. The gyromagnetic ratio g, in particular, is explicitly shown to be non-constant in higher order, and thus to deviate from its lowest order value, g=3. Comparison of the perturbative analytical solutions with their non-perturbative numerical counterparts shows remarkable agreement.Comment: RevTeX style, 4 pages, 5 figure

Guiding criteria for instrument design at long-pulse neutron sources

6 págs.; 3 figs.; 7th Meeting of the Spanish Neutron Scattering Association (SETN); Open Access funded by Creative Commons Atribution Licence 3.0We introduce and describe general criteria which characterize long-pulse neutron sources, with a view to guiding and facilitating subsequent instrument design and optimization for specific applications. The ensuing analysis shows that a long-pulse neutron source allows for the possibility of a wide range of flexible instrument concepts with variable resolution and dynamic range, tasks which invariably require the implementation of pulse-modulation techniques in the time domain, particularly for high-resolution applications. We also consider in some detail yet-to-be-tapped opportunities in the use of shorter proton pulses, characterised by a duration commensurate with typical moderation times at spallation sources.This work would not have been possible without the support of the computing infrastructure of the i2BASQUE Academic Network and the support of the ESS-DMSC Computing Centre.Peer Reviewe

Concepto y Taxonomía de la Industria de la Comunicación

La industria de la comunicación comprende el conjunto de empresas que participan en el mercado de las ideas ofertando algunos contenidos (informativos, persuasivos o de entretenimiento) demandados por variados públicos (audiencia, anunciantes o instituciones) utilizando ciertos medios tecnológicos (impresos, audiovisuales o multimedia). El estudio científico de los aspectos económicos y empresariales de los medios de comunicación tiene en España una historia no superior a los cincuenta años, mientras que otros países como Estados Unidos o Alemania cuentan con más tradición. Sin embargo, las propuestas de clasificación de los sectores de la industria han sido variadas y heterogéneas en todos los casos. Esta investigación pretende aportar un sistema de clasificación a partir del cual se puedan definir los sectores y mercados de la comunicación de un modo integrado tanto en el ámbito académico como en el empresarial y regulatorio

Poly-instanton Inflation

We propose a new inflationary scenario in type IIB Calabi-Yau compactifications, where the inflaton is a K\"ahler modulus parameterising the volume of an internal four-cycle. The inflaton potential is generated via poly-instanton corrections to the superpotential which give rise to a naturally flat direction due to their double exponential suppression. Given that the volume mode is kept stable during inflation, all the inflaton-dependent higher dimensional operators are suppressed. Moreover, string loop effects can be shown to be negligible throughout all the inflationary dynamics for natural values of the underlying parameters. The model is characterised by a reheating temperature of the order $T_{\rm rh}\simeq 10^6$ GeV which requires $N_e \simeq 54$ e-foldings of inflation. All the inflationary observables are compatible with current observations since the spectral index is $n_s \simeq 0.96$, while the tensor-to-scalar ratio is $r\simeq 10^{-5}$. The volume of the Calabi-Yau is of order $10^3$ in string units, corresponding to an inflationary scale around $10^{15}$ GeVComment: 20 pages, 4 figure

Using ion beams to tune the nanostructure and optical response of co-deposited Ag : BBBN thin films

The present study is devoted to co-deposited Ag : BN nanocermet thin films and is focused on the influence of ion irradiation conditions on their structural and linear optical properties. Ion irradiation was performed in situ during the growth of the nanocermets using a 50 eV assistance beam (nitrogen/argon or nitrogen-ion assistance) and ex situ on as-grown films using a 120 keV argon-ion beam (post-irradiation). Grazing incidence small-angle x-ray scattering measurements show that (i) as-grown N-assisted films contain prolate spheroidal clusters (height-to-diameter ratio H/D ≈ 1.8), (ii) N/Ar-ion assistance leads to the formation of more elongated clusters (H/D ≈ 2.1) and (iii) post-irradiation leads to a decrease of H/D to a value close to 1. These results are discussed on the basis of atomic diffusion processes involved during the growth of the nanocermets and during the post-irradiation. The optical transmittance spectra of these films measured at normal incidence display one absorption band, due to the excitation of the (1,1) plasmon mode of the clusters. In the case of the as-grown films, an additional band appears at oblique incidence for P-polarized light, as a consequence of the excitation of the (1,0) plasmon mode of the clusters. Our results show that the spectral position of the absorption bands (which can be tuned in the 400-600 nm range) depends on the H/D ratio of the clusters, in good agreement with calculations of optical transmittance considering the nanocomposite layer as a uniaxial anisotropic medium whose dielectric tensor is described by an anisotropic Maxwell-Garnett model. © 2007 IOP Publishing Ltd.The authors would like to thank CNRS-CSIC and Picasso programmes for financial support which permitted the collaboration between the Instituto de Ciencia de Materiales de Sevilla (Spain) and the Laboratoire de Metallurgie Physique ´ de Poitiers (France). The authors also thank J P Simon and the D2AM staff at the ESRF for their support during the GISAXS measurements.Peer Reviewe

Salinity tolerance as a factor controlling spatial patterns in composition and structure of zooplankton in the Guadalquivir estuary

Trabajo presentado en ECSA 56 (Coastal systems in transition: From a 'natural' to an 'anthropogenically-modified' state), celebrado en Bremen del 4 al 7 de septiembre de 2016.N

Laser treatment of nanoparticulated metal thin films for ceramic tile decoration

This paper presents a new method for the fabrication of metal-like decorative layers on glazed ceramic tiles. It consists of the laser treatment of copper thin films prepared by electron beam evaporation at glancing angles. A thin film of discontinuous copper nanoparticles was electron beam evaporated in an oblique angle configuration onto ceramic tiles and an ample palette of colors obtained by laser treatment both in air and in vacuum. Scanning electron microscopy (SEM and FESEM) along with UV-vis-NIR spectroscopy and time of flight secondary ion mass spectrometry (TOF-SIMS) analysis were used to characterize the differently colored layers. Based on these analyses, color development has been accounted for by a simple model considering surface melting phenomena and different microstructural and chemical transformations of the outmost surface layers of samples.Financial support from the EU (Grant LIFE11/ENV/ES560), Innovaragon (Grant ITA-DGA/ES 1368), DGA (Group T87), MINECO (Projects MAT2013-40852-R and MAT2013-42900-P), and Junta de Andalucia (Projects TEP 8067 and FQM 6900) is gratefully acknowledged. F.R.-G. acknowledges the Portuguese Science and Technology Foundation for Grant SFRH/BPD/108581/2015.Peer reviewe