The regime of electromagnetically induced transparency in optically dense media: from atoms to excitons

The phenomenon of electromagnetically induced transparency (EIT) was discovered by Adriano Gozzini and coworkers in 1976 in Pisa. Novel schemes to investigate and exploit EIT in the optical domain have attracted much interest both in atomic and solid state systems. We discuss some of our recent theoretical results, in particular: i) a well developed EIT regime based on free exciton levels in undoped bulk crystalline Cu2O; ii) light dragging effects in moving media under EIT; iii) the coherent control of Cherenkov radiation in the EIT regime

ANÁLISE DA REESTRUTURAÇÃO IMOBILIÁRIA NO MUNICÍPIO DE SERRA (ES): ESTUDO DOS CONDOMÍNIOS INDUSTRIAIS

O presente trabalho tem como objetivo a análise dos condomínios industriais no município de Serra (ES) tendo em vista que esses são considerados novos produtos imobiliários e também componentes da atual reestruturação imobiliária, que tem, na sua forma particular de reprodução, um papel proeminente para a nova atuação do mercado imobiliário no município. Os condomínios industriais são produtos imobiliários contemporâneos que, abrigam em seu arranjo interno a indústria e outras forma de reprodução do capital. São produtos de uma nova fase da produção da cidade que nega a forma antiga centro-periferia, e ressalta a produção de novas centralidades, originando o espraiamento do tecido urbano. Esses empreendimentos podem ser promovidos tanto pelo capital estatal, quanto pelo capital provado, mas em ambos os casos, o que se tem em vista é a disputa pelo monopólio espacial e a consequente obtenção de uma parte da mais-valia transfigurada sobre a forma de renda da terra. A área escolhida para o levantamento dos condomínios empresariais analisados foi a do município de Serra, município integrante da Região Metropolitana da Grande Vitória (RMGV) e importante amostra representativa da reestruturação urbana no espaço metropolitano de Vitória. Os resultados demonstram que os condomínios industriais em Serra, são mais do que um produto imobiliário novo, demarcam um período onde o poder municipal prioriza a produção imobiliária em suas políticas favorecendo esse nicho da esfera produtiva à pratica progressiva de preços de monopólio sobre o espaço da cidade

Ab-initio calculations of the optical properties of the Si(113)3x2ADI surface

We investigated the stable silicon (113) surface with a 3x2ADI reconstruction by ab-initio methods. The ground state properties have been obtained using the density-functional theory. We present the dispersion of the electronic band structure, where the surface bands have been distinguished from the projected bulk bands by calculating their localization in the slab. The optical spectra, here the reflectance anisotropy (RAS), have been obtained within the independent particle random phase approximation. We identified surface features in the spectra tracing them back to the responsible electronic states and, studied their localization in the slab. A comparison with available experimental data for the band structure and the RAS shows a good agreement.Comment: 10 pages, 10 figure

BeppoSAX average spectra of Seyfert galaxies

We have studied the average 3-200 keV spectra of Seyfert galaxies of type 1 and 2, using data obtained with BeppoSAX. The average Seyfert 1 spectrum is well-fitted by a power law continuum with photon spectral index Gamma~1.9, a Compton reflection component R~0.6-1 (depending on the inclination angle between the line of sight and the reflecting material) and a high-energy cutoff at around 200 keV; there is also an iron line at 6.4 keV characterized by an equivalent width of 120 eV. Seyfert 2's on the other hand show stronger neutral absorption (NH=3-4 x 10^{22} atoms cm-2) as expected but are also characterized by an X-ray power law which is substantially harder (Gamma~1.75) and with a cut-off at lower energies (E_c~130 keV); the iron line parameters are instead substantially similar to those measured in type 1 objects. There are only two possible solutions to this problem: to assume more reflection in Seyfert 2 galaxies than observed in Seyfert 1 or more complex absorption than estimated in the first instance. The first possibility is ruled out by the Seyfert 2 to Seyfert 1 ratio while the second provides an average Seyfert 2 intrinsic spectrum very similar to that of the Seyfert 1. The extra absorber is likely an artifact due to summing spectra with different amounts of absorption, althought we cannot exclude its presence in at least some individual sources. Our result argues strongly for a very similar central engine in both type of galaxies as expected under the unified theory.Comment: 12 pages, 4 figures, to be published in ApJ Letter

Critical assessment of thermal conductivity models for Miscibility Gap Alloy-based composite Phase Change Materials for high temperature Thermal Energy Storage

Miscibility Gap Alloys (MGAs), such as Al-Sn-based systems, provide a viable solution for the development of composite Phase Change Materials (PCMs) for Thermal Energy Storage (TES) purposes. Their successful production depends on the cooling rate imposed to the melt. Finite Element Analyses (FEA), which relies also on thermal conductivity values, represent a powerful tool for the design of the production process. Thermal conductivity, which depends on the arrangement of the phases in the system, also affects the thermal response of the alloy. In the view of evaluating the impact of the phase morphology, the authors adapted some of the models developed for composites and solutions to Al-Sn and Al-Sn-Si-Mg alloys, characterized by broad solidification ranges in terms of composition and temperature and by significantly different phases thermal conductivity. In the fully-liquid range, Filippov and Novoselova model was selected for the description of both alloys. Models that consider sphere-like dispersions give values quite close to the theoretical upper Wiener bound when the high-melting phase is solid. The phase morphology impact is relevant when the solidification range is considered. The resulting arrangement-related thermal conductivity curves are compared to those supplied by CALPHAD-based software and to available literature data

Variable broad lines and outflow in the weak blazar PBC J2333.9-2343

Indexación: Scopus; Scielo.Funding text #1 1Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile 2INAF – Istituto di Astrofisica e Planetologia Spaziali di Roma (IAPS-INAF), Via del Fosso del Cavaliere 100, I-00133 Roma, Italy 3INAF – Osservatorio Astronomico di Roma, via Frascati 33, I-00078 Monte Porzio Catone, Italy 4Excellence Cluster Universe, Technische Universität München, Boltzmannstr. 2, D-85748, Garching, Germany 5European Southern Observatory, Karl-Schwarzschild-Str 2, D-85748 Garching b. München, Germany 6Instituto Nacional de Astrofísica, Óptica y Electrónica, Apartado Postal 51-216, 72000 Puebla, México 7Argelander Institute for Astronomy, University of Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany 8International Max Planck Research School of Astronomy and Astrophysics at the Universities of Bonn and Cologne, Auf dem Hügel 69, D-53121 Bonn, Germany 9INAF – Osservatorio di Astrofisica e Scienza dello Spazio, via Gobetti 93/3, I-40129 Bo...View all Funding text #2 We acknowledge the referee, M. Villar Martín, for her comments and suggestions that helped to improve the paper. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester, the NASA/IPAC extragalactic database (NED), the STARLIGHT code, and the IRAF software. Based upon observations carried out at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir (OAN-SPM), Baja California, México. LHG and FP acknowledge the ASI/INAF agreement number 2013-023-R1, LHG partial support from FONDECYT through grant 3170527, MP from ESSTI under the MoST, and from MINECO through research projects AYA2013-42227-P and AYA2016-76682-C3-1-P (AEI/FEDER, UE), LHG and SC from the Spanish grant AYA2013-42227-P, VC by CONACyT research grant 280789, EFJA from the Collaborative Research Center 956, subproject A1, funded by DFG, and GV from the DFG Cluster of Excellence ‘Origin and Structure of the Universe’ (www.universe-cluster.de).PBC J2333.9-2343 is a peculiar active nucleus with two giant radio lobes and a weak blazarlike nucleus at their centre. In this work we show new optical, ultraviolet (UV), and X-ray data taken from the San Pedro Mártir telescope, the New Technology Telescope, NTT/EFOSC2, and the Swift/XRT satellite. The source is highly variable at all frequencies, in particular the strongest variations are found in the broad Hα component with a flux increase of 61±4 per cent between 2009 and 2016, following the X-ray flux increase of 62±6 per cent between 2010 and 2016. We also detected a broad Hβ component in 2016, making the optical classification change from type 1.9 to type 1.8 in 1 yr. We have also detected a broad component of the [OIII]λ5007 line, which is blue-shifted and of high velocity, suggesting an origin from a highly disturbed medium, possibly an outflow. The line flux variability and broad widths are indicative of a jet that is, at least in part, responsible for the ionization of the broad line region (BLR) and narrow line region (NLR). © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.https://academic.oup.com/mnras/article-abstract/478/4/4634/4999938?redirectedFrom=fulltex

Revealing the active galactic nucleus in the superantennae through L-band spectroscopy

We present an L-band spectrum of the Ultraluminous Infrared Galaxy IRAS 19254-7245 (the Superantennae), obtained with VLT-ISAAC. The high signal to noise ratio allows a study of the main spectral features with unprecedented detail for an extragalactic source. We argue that the main energy source in the IR is an obscured AGN. This is indicated by the low equivalent width of the 3.3 micron PAH feature, the broad absorption feature at 3.4 um, and the steep continuum at lambda>3.7 um (f_lambda ~lambda^(2.7)). The substructure of the 3.4 um absorption feature indicates that the absorption is due to hydrocarbon chains of 6-7 carbon atoms.Comment: 12 pages, 3 figures. ApJ Letters, in pres

Functional methods in the theory of magnetoimpurity states of electrons in quantum wires

Functional methods are used to study magnetoimpurity states of electrons in nanostructures. The Keldysh formalism is applied to these states. The theory is illustrated using a quantum wire sample with impurity atoms capable of localizing electrons in a magnetic field. The characteristics of magnetoimpurity states of electrons in the wire are calculated using the model of a Gaussian separable potential.Comment: 15 pages, 1 figur