On the nature of the near-UV extended light in Seyfert galaxies

We study the nature of the extended near-UV emission in the inner kiloparsec of a sample of 15 Seyfert galaxies which have both near-UV (F330W) and narrow band [OIII] high resolution Hubble images. For the majority of the objects we find a very similar morphology in both bands. From the [OIII] images we construct synthetic images of the nebular continuum plus the emission line contribution expected through the F330W filter, which can be subtracted from the F330W images. We find that the emission of the ionised gas dominates the near-UV extended emission in half of the objects. A further broad band photometric study, in the bands F330W (U), F547M (V) and F160W (H), shows that the remaining emission is dominated by the underlying galactic bulge contribution. We also find a blue component whose nature is not clear in 4 out of 15 objects. This component may be attributed to scattered light from the AGN, to a young stellar population in unresolved star clusters, or to early-disrupted clusters. Star forming regions and/or bright off-nuclear star clusters are observed in 4/15 galaxies of the sample.Comment: 23 pages, 6 figures, 3 tables; accepted for publication in MNRA

Trapping of three-dimensional electrons and transition to two-dimensional transport in the three-dimensional topological insulator Bi2Se3 under high pressure

[EN] This paper reports an experimental and theoretical investigation on the electronic structure of bismuth selenide (Bi2Se3) up to 9 GPa. The optical gap of Bi2Se3 increases from 0.17 eV at ambient pressure to 0.45 eV at 8 GPa. The quenching of the Burstein-Moss effect in degenerate samples and the shift of the free-carrier plasma frequency to lower energies reveal a quick decrease of the bulk three-dimensional (3D) electron concentration under pressure. On increasing pressure the behavior of Hall electron concentration and mobility depends on the sample thickness, consistently with a gradual transition from mainly 3D transport at ambient pressure to mainly two-dimensional (2D) transport at high pressure. Two-carrier transport equations confirm the trapping of high-mobility 3D electrons, an effect that can be related to a shallow-to-deep transformation of donor levels, associated with a change in the ordering of the conduction band minima. The high apparent areal density and low electron mobility of 2D electrons are not compatible with their expected properties in a Dirac cone. Measured transport parameters at high pressure are most probably affected by the presence of holes, either in an accumulation surface layer or as minority carriers in the bulk. ©2012 American Physical SocietyThis work has been done under financial support from Spanish MICINN under Grants No. MAT2008-06873-C02-02, No. MAT2007-66129, No. MAT2010-21270-C04-03/04, No. CSD2007-00045, and Prometeo No. GV2011/035. The supercomputer time has been provided by the Red Espanola de Supercomputacion (RES) and the MALTA cluster.Segura, A.; Panchal, V.; Sánchez-Royo, JF.; Marín-Borrás, V.; Muñoz-Sanjosé, V.; Rodríguez-Hernández, P.; Muñoz, A.... (2012). Trapping of three-dimensional electrons and transition to two-dimensional transport in the three-dimensional topological insulator Bi2Se3 under high pressure. Physical Review B. 85:195139-1-195139-9. https://doi.org/10.1103/PhysRevB.85.195139S195139-1195139-985Mishra, S. K., Satpathy, S., & Jepsen, O. (1997). Electronic structure and thermoelectric properties of bismuth telluride and bismuth selenide. Journal of Physics: Condensed Matter, 9(2), 461-470. doi:10.1088/0953-8984/9/2/014Hor, Y. S., Richardella, A., Roushan, P., Xia, Y., Checkelsky, J. G., Yazdani, A., … Cava, R. J. (2009). p-typeBi2Se3for topological insulator and low-temperature thermoelectric applications. Physical Review B, 79(19). doi:10.1103/physrevb.79.195208Zhang, H., Liu, C.-X., Qi, X.-L., Dai, X., Fang, Z., & Zhang, S.-C. (2009). Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface. Nature Physics, 5(6), 438-442. doi:10.1038/nphys1270Hasan, M. Z., & Kane, C. L. (2010). Colloquium: Topological insulators. Reviews of Modern Physics, 82(4), 3045-3067. doi:10.1103/revmodphys.82.3045Moore, J. E. (2010). The birth of topological insulators. Nature, 464(7286), 194-198. doi:10.1038/nature08916Xia, Y., Qian, D., Hsieh, D., Wray, L., Pal, A., Lin, H., … Hasan, M. Z. (2009). Observation of a large-gap topological-insulator class with a single Dirac cone on the surface. Nature Physics, 5(6), 398-402. doi:10.1038/nphys1274Chen, Y. L., Analytis, J. G., Chu, J.-H., Liu, Z. K., Mo, S.-K., Qi, X. L., … Shen, Z.-X. (2009). Experimental Realization of a Three-Dimensional Topological Insulator, Bi2Te3. Science, 325(5937), 178-181. doi:10.1126/science.1173034Hsieh, D., Xia, Y., Qian, D., Wray, L., Dil, J. H., Meier, F., … Hasan, M. Z. (2009). A tunable topological insulator in the spin helical Dirac transport regime. Nature, 460(7259), 1101-1105. doi:10.1038/nature08234Alpichshev, Z., Analytis, J. G., Chu, J.-H., Fisher, I. R., Chen, Y. L., Shen, Z. X., … Kapitulnik, A. (2010). STM Imaging of Electronic Waves on the Surface ofBi2Te3: Topologically Protected Surface States and Hexagonal Warping Effects. Physical Review Letters, 104(1). doi:10.1103/physrevlett.104.016401Roushan, P., Seo, J., Parker, C. V., Hor, Y. S., Hsieh, D., Qian, D., … Yazdani, A. (2009). Topological surface states protected from backscattering by chiral spin texture. Nature, 460(7259), 1106-1109. doi:10.1038/nature08308Butch, N. P., Kirshenbaum, K., Syers, P., Sushkov, A. B., Jenkins, G. S., Drew, H. D., & Paglione, J. (2010). Strong surface scattering in ultrahigh-mobilityBi2Se3topological insulator crystals. Physical Review B, 81(24). doi:10.1103/physrevb.81.241301Wang, Z., Lin, T., Wei, P., Liu, X., Dumas, R., Liu, K., & Shi, J. (2010). Tuning carrier type and density in Bi2Se3 by Ca-doping. Applied Physics Letters, 97(4), 042112. doi:10.1063/1.3473778Ren, Z., Taskin, A. A., Sasaki, S., Segawa, K., & Ando, Y. (2010). Large bulk resistivity and surface quantum oscillations in the topological insulatorBi2Te2Se. Physical Review B, 82(24). doi:10.1103/physrevb.82.241306Kulbachinskii, V. A., Miura, N., Nakagawa, H., Arimoto, H., Ikaida, T., Lostak, P., & Drasar, C. (1999). Conduction-band structure ofBi2−xSbxSe3mixed crystals by Shubnikov–de Haas and cyclotron resonance measurements in high magnetic fields. Physical Review B, 59(24), 15733-15739. doi:10.1103/physrevb.59.15733Analytis, J. G., McDonald, R. D., Riggs, S. C., Chu, J.-H., Boebinger, G. S., & Fisher, I. R. (2010). Two-dimensional surface state in the quantum limit of a topological insulator. Nature Physics, 6(12), 960-964. doi:10.1038/nphys1861Cho, S., Butch, N. P., Paglione, J., & Fuhrer, M. S. (2011). Insulating Behavior in Ultrathin Bismuth Selenide Field Effect Transistors. Nano Letters, 11(5), 1925-1927. doi:10.1021/nl200017fZhang, Y., He, K., Chang, C.-Z., Song, C.-L., Wang, L.-L., Chen, X., … Xue, Q.-K. (2010). Crossover of the three-dimensional topological insulator Bi2Se3 to the two-dimensional limit. Nature Physics, 6(8), 584-588. doi:10.1038/nphys1689Kong, D., Cha, J. J., Lai, K., Peng, H., Analytis, J. G., Meister, S., … Cui, Y. (2011). Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi2Se3. ACS Nano, 5(6), 4698-4703. doi:10.1021/nn200556hBenia, H. M., Lin, C., Kern, K., & Ast, C. R. (2011). Reactive Chemical Doping of theBi2Se3Topological Insulator. Physical Review Letters, 107(17). doi:10.1103/physrevlett.107.177602King, P. D. C., Hatch, R. C., Bianchi, M., Ovsyannikov, R., Lupulescu, C., Landolt, G., … Hofmann, P. (2011). Large Tunable Rashba Spin Splitting of a Two-Dimensional Electron Gas inBi2Se3. Physical Review Letters, 107(9). doi:10.1103/physrevlett.107.096802Hamlin, J. J., Jeffries, J. R., Butch, N. P., Syers, P., Zocco, D. A., Weir, S. T., … Maple, M. B. (2011). High pressure transport properties of the topological insulator Bi2Se3. Journal of Physics: Condensed Matter, 24(3), 035602. doi:10.1088/0953-8984/24/3/035602Köhler, H., & Hartmann, J. (1974). Burstein Shift of the Absorption Edge of nBi2Se3. physica status solidi (b), 63(1), 171-176. doi:10.1002/pssb.2220630116Panchal, V., Segura, A., & Pellicer-Porres, J. (2011). Low-cost set-up for Fourier-transform infrared spectroscopy in diamond anvil cell from 4000 to 400 cm−1. High Pressure Research, 31(3), 445-453. doi:10.1080/08957959.2011.594049Chervin, J. C., Canny, B., Besson, J. M., & Pruzan, P. (1995). A diamond anvil cell for IR microspectroscopy. Review of Scientific Instruments, 66(3), 2595-2598. doi:10.1063/1.1145594Piermarini, G. J., Block, S., Barnett, J. D., & Forman, R. A. (1975). Calibration of the pressure dependence of theR1ruby fluorescence line to 195 kbar. Journal of Applied Physics, 46(6), 2774-2780. doi:10.1063/1.321957Errandonea, D., Segura, A., Martínez-García, D., & Muñoz-San Jose, V. (2009). Hall-effect and resistivity measurements in CdTe and ZnTe at high pressure: Electronic structure of impurities in the zinc-blende phase and the semimetallic or metallic character of the high-pressure phases. Physical Review B, 79(12). doi:10.1103/physrevb.79.125203Errandonea, D., Martínez-García, D., Segura, A., Ruiz-Fuertes, J., Lacomba-Perales, R., Fages, V., … Mũnoz-San José, V. (2006). High-pressure electrical transport measurements on p-type GaSe and InSe. High Pressure Research, 26(4), 513-516. doi:10.1080/08957950601101787Hohenberg, P., & Kohn, W. (1964). Inhomogeneous Electron Gas. Physical Review, 136(3B), B864-B871. doi:10.1103/physrev.136.b864Kresse, G., & Hafner, J. (1993). Ab initiomolecular dynamics for liquid metals. Physical Review B, 47(1), 558-561. doi:10.1103/physrevb.47.558Kresse, G., & Hafner, J. (1994). Ab initiomolecular-dynamics simulation of the liquid-metal–amorphous-semiconductor transition in germanium. Physical Review B, 49(20), 14251-14269. doi:10.1103/physrevb.49.14251Kresse, G., & Furthmüller, J. (1996). Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Computational Materials Science, 6(1), 15-50. doi:10.1016/0927-0256(96)00008-0Kresse, G., & Furthmüller, J. (1996). Efficient iterative schemes forab initiototal-energy calculations using a plane-wave basis set. Physical Review B, 54(16), 11169-11186. doi:10.1103/physrevb.54.11169Blöchl, P. E. (1994). Projector augmented-wave method. Physical Review B, 50(24), 17953-17979. doi:10.1103/physrevb.50.17953Kresse, G., & Joubert, D. (1999). From ultrasoft pseudopotentials to the projector augmented-wave method. Physical Review B, 59(3), 1758-1775. doi:10.1103/physrevb.59.1758Perdew, J. P., Ruzsinszky, A., Csonka, G. I., Vydrov, O. A., Scuseria, G. E., Constantin, L. A., … Burke, K. (2008). Restoring the Density-Gradient Expansion for Exchange in Solids and Surfaces. Physical Review Letters, 100(13). doi:10.1103/physrevlett.100.136406Mujica, A., Rubio, A., Muñoz, A., & Needs, R. J. (2003). High-pressure phases of group-IV, III–V, and II–VI compounds. Reviews of Modern Physics, 75(3), 863-912. doi:10.1103/revmodphys.75.863Köhler, H., & Becker, C. R. (1974). Optically Active Lattice Vibrations in Bi2Se3. physica status solidi (b), 61(2), 533-537. doi:10.1002/pssb.2220610218Vilaplana, R., Santamaría-Pérez, D., Gomis, O., Manjón, F. J., González, J., Segura, A., … Kucek, V. (2011). Structural and vibrational study of Bi2Se3under high pressure. Physical Review B, 84(18). doi:10.1103/physrevb.84.184110LaForge, A. D., Frenzel, A., Pursley, B. C., Lin, T., Liu, X., Shi, J., & Basov, D. N. (2010). Optical characterization ofBi2Se3in a magnetic field: Infrared evidence for magnetoelectric coupling in a topological insulator material. Physical Review B, 81(12). doi:10.1103/physrevb.81.125120Penn, D. R. (1962). 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K., & Sahu, B. (2011). Dielectric capping effects on binary and ternary topological insulator surface states. Physical Review B, 84(15). doi:10.1103/physrevb.84.155105Suski, T., Piotrzkowski, R., Wiśniewski, P., Litwin-Staszewska, E., & Dmowski, L. (1989). High pressure andDXcenters in heavily doped bulk GaAs. Physical Review B, 40(6), 4012-4021. doi:10.1103/physrevb.40.4012Errandonea, D., Segura, A., Sánchez-Royo, J. F., Mun-|Atoz, V., Grima, P., Chevy, A., & Ulrich, C. (1997). Investigation of conduction-band structure, electron-scattering mechanisms, and phase transitions in indium selenide by means of transport measurements under pressure. Physical Review B, 55(24), 16217-16225. doi:10.1103/physrevb.55.16217Analytis, J. G., Chu, J.-H., Chen, Y., Corredor, F., McDonald, R. D., Shen, Z. X., & Fisher, I. R. (2010). Bulk Fermi surface coexistence with Dirac surface state inBi2Se3: A comparison of photoemission and Shubnikov–de Haas measurements. 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Linezolid therapy for infective endocarditis

AbstractLinezolid is not yet recognised as a standard therapy for infective endocarditis. This report describes nine patients with endocarditis treated with linezolid and 33 similar cases from the medical literature. The majority of cases involved multiresistant strains, and the reasons for administering linezolid were refractory disease (60%), intolerance (28%), sequential therapy (12%) and a resistant pathogen (1%). Linezolid was administered for a mean of 37 days, with a successful outcome in 79% of cases. Reversible adverse effects were described in ten cases. The mean follow-up period was 8.5 months. Further data from randomised controlled clinical trials are needed to determine the efficacy and safety of linezolid for treating endocarditis

ZnMgO-based UV photodiodes: a comparison of films grown by spray pyrolysis and MBE

Detecting the UV part of the spectrum is fundamental for a wide range of applications where ZnMgO has the potential to play a central role. The shortest achievable wavelength is a function of the Mg content in the films, which in turn is dependent on the growth technique. Moreover, increasing Mg contents lead to an electrical compensation of the films, which directly affects the responsivity of the photodetectors. In addition, the metal-semiconductor interface and the presence of grain boundaries have a direct impact on the responsivity through different gain mechanisms. In this work, we review the development of ZnMgO UV Schottky photodiodes using molecular beam epitaxy and spray pyrolysis, and we analyze and compare the physical mechanisms underlying the photodetector behavior. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Ultrasonography detection of pregnancy in outdoor iberian sows

In a flock of pure Iberian sows, with outdoor breeding and total freedom, ultrasonography detection of pregnancy length is studied (11.1±0.6 seconds), according to pregnancy or not pregnancy (9.7 vs 20.4 seconds). Also, possible influence of cycle number is analysed. By other side permanence of ear tags after a year is valued (99.5%). Results show that indoor and intensive production is not justified in order to attain more reproductive control.En un rebaño de cerdas Ibéricas puras, criadas en régimen de total libertad (sin empleo de jaulas), se estudia el tiempo empleado en el diagnóstico de gestación con ecógrafo (11,1±0,6 segundos por cerda), se analiza la duración del diagnóstico dependiendo de si hay preñez o no (9,7 vs 20,4 segundos) y la posible influencia del número de ciclo. Por otra parte se valora la permanencia de los crotales de identificación individual tras un año (99,5%). Los resultados indican que la intensificación de la producción en esta raza no está justificada por la consecución de un mayor control reproductivo

Structural and vibrational study of Bi2Se3 under high pressure

The structural and vibrational properties of bismuth selenide (Bi2Se3) have been studied by means of x-ray diffraction and Raman scattering measurements up to 20 and 30 GPa, respectively. The measurements have been complemented with ab initio total-energy and lattice dynamics calculations. Our experimental results evidence a phase transition from the low-pressure rhombohedral (R-3m) phase (B-Bi2Se3) with sixfold coordination for Bi to a monoclinic C2/m structure (B-Bi2Se3) with sevenfold coordination for Bi above 10 GPa. The equation of state and the pressure dependence of the lattice parameters and volume of a and B phases of Bi2Se3 are reported. Furthermore, the presence of a pressure-induced electronic topological phase transition in B-Bi2Se3 is discussed. Raman measurements evidence that Bi2Se3 undergoes two additional phase transitions around 20 and 28 GPa, likely toward a monoclinic C2/c and a disordered body-centered cubic structure with 8-fold and 9- or 10-fold coordination, respectively. These two high-pressure structures are the same as those recently found at high pressures in Bi2Te3 and Sb2Te3. On pressure release, Bi2Se3 reverts to the original rhombohedral phase after considerable hysteresis. Symmetries, frequencies, and pressure coefficients of the Raman and infrared modes in the different phases are reported and discussed.This work was done under financial support from Spanish Ministry of Science and Innovation under Projects No. MAT2007-66129, No. MAT2010-21270-C04-03/04, and No. CSD-2007-00045 and from the Valencian government under Project No. Prometeo/2011-035. It is also supported by the Ministry of Education, Youth and Sports of the Czech Republic Project No. MSM 0021627501

Glucose uptake in Prochlorococcus: diversity of kinetics and effects on the metabolism

We have previously shown that Prochlorococcus sp. SS120 strain takes up glucose by using a multiphasic transporter encoded by the Pro1404 gene. Here, we studied the glucose uptake kinetics in multiple Prochlorococcus strains from different ecotypes, observing diverse values for the Ks constants (15–126.60 nM) and the uptake rates (0.48–6.36 pmol min-1 mg prot-1). Multiphasic kinetics was observed in all studied strains, except for TAK9803-2. Pro1404 gene expression studies during the 21st Atlantic Meridional Transect cruise showed positive correlation with glucose concentrations in the ocean. This suggests that the Pro1404 transporter has been subjected to diversification along the Prochlorococcus evolution, in a process probably driven by the glucose availabilities at the different niches it inhabits. The glucose uptake mechanism seems to be a primary transporter. Glucose addition induced detectable transcriptomic and proteomic changes in Prochlorococcus SS120, but photosynthetic efficiency was unaffected. Our studies indicate that glucose is actively taken up by Prochlorococcus, but its uptake does not significantly alter the trophic ways of this cyanobacterium, which continues performing photosynthesis. Therefore Prochlorococcus seems to remain acting as a fundamentally phototrophic organism, capable of using glucose as an extra resource of carbon and energy when available in the environment

High-pressure vibrational and optical study of Bi2Te3

We report an experimental and theoretical lattice dynamics study of bismuth telluride (Bi2Te3) up to 23 GPa together with an experimental and theoretical study of the optical absorption and reflection up to 10 GPa. The indirect bandgap of the low-pressure rhombohedral (R-3m) phase (α-Bi2Te3) was observed to decrease with pressure at a rate of −6 meV/GPa. In regard to lattice dynamics, Raman-active modes of α-Bi2Te3 were observed up to 7.4 GPa. The pressure dependence of their frequency and width provides evidence of the presence of an electronic-topological transition around 4.0 GPa. Above 7.4 GPa a phase transition is detected to the C2/m structure. On further increasing pressure two additional phase transitions, attributed to the C2/c and disordered bcc (Im-3m) phases, have been observed near 15.5 and 21.6 GPa in good agreement with the structures recently observed by means of x-ray diffraction at high pressures in Bi2Te3. After release of pressure the sample reverts back to the original rhombohedral phase after considerable hysteresis. Raman- and IR-mode symmetries, frequencies, and pressure coefficients in the different phases are reported and discussed.This work has been done under financial support from Spanish MICINN under projects MAT2008-06873-C02- 02, MAT2007-66129, Prometeo/2011-035, MAT2010-21270-C04-03/04, and CSD2007-00045 and supported by the Ministry of Education, Youth and Sports of the Czech Republic (MSM 0021627501)

An Atlas of the circumnuclear regions of 75 Seyfert galaxies in the near-UV with HST Advanced Camera for Surveys

We present an atlas of the central regions of 75 Seyfert galaxies imaged in the near-UV with the Advanced Camera for Surveys of the Hubble Space Telescope at an average resolution of ~10pc. These data complement archival high resolution data from the Space Telescope at optical and near-IR wavelengths, creating an extremely valuable dataset for astronomers with a broad range of scientific interests. Our goal is to investigate the nature of the near-UV light in these objects, its relation to the circumnuclear starburst phenomenon, and the connection of this to the evolution and growth of the galaxy bulge and central black hole. In this paper, we describe the near-UV morphology of the objects and characterize the near-UV emission. We estimate the size and the luminosity of the emitting regions and extract the luminosity profile. We also determine the presence of unresolved compact nuclei. In addition, the circumnuclear stellar cluster population is identified, and the contribution of the stellar clusters to the total light, at this wavelength, is estimated. The size of the sample allows us to draw robust statistical conclusions. We find that {Seyfert 1} galaxies are completely dominated by its bright and compact nucleus, that remains point-like at this resolution, while we find almost no unresolved nucleus in Seyfert 2. The Seyfert types 1 and 2 are quite segregated in an asymmetry vs compactness plot. Stellar clusters are found somewhat more frequently in Sy2 (in ~70% of the galaxies) than in Sy1 (~57%), and contribute more to the total light in Sy2, but this two differences seem to be mostly due to the large contribution of the compact nucleus in Sy1, as the luminosity distribution of the clusters is similar in both Sy types.Comment: Accepted for publication in AJ, 58 pages, 20 figures. High-resolution figures for all the objects are available at http://www.iaa.es/~manuel/publications/paper01.htm