X-ray spectral variability of seven LINER nuclei with XMM-Newton and Chandra data

One of the most important features in active galactic nuclei (AGN) is the variability of their emission. Variability has been discovered at X-ray, UV, and radio frequencies on time scales from hours to years. Among the AGN family and according to theoretical studies, Low-Ionization Nuclear Emission Line Region (LINER) nuclei would be variable objects on long time scales. Our purpose is to investigate spectral X-ray variability in LINERs and to understand the nature of these kinds of objects, as well as their accretion mechanism. Chandra and XMM-Newton public archives were used to compile X-ray spectra of seven LINER nuclei at different epochs with time scales of years. To search for variability we fit all the spectra from the same object with a set of models, in order to identify the parameters responsible for the variability pattern. We also analyzed the light curves in order to search for short time scale (from hours to days) variability. Whenever possible, UV variability was also studied. We found spectral variability in four objects, with variations mostly related to hard energies (2-10 keV). These variations are due to changes in the soft excess, and/or changes in the absorber, and/or intrinsic variations of the source. Another two galaxies seem not to vary. Short time scale variations during individual observations were not found. Our analysis confirms the previously reported anticorrelation between the X-ray spectral index and the Eddington ratio, and also the correlation between the X-ray to UV flux ratio and the Eddington ratio. These results support an Advection Dominated Accretion Flow (ADAF) as the accretion mechanism in LINERs.Comment: 35 pages, 53 figures, recently accepted pape

X-ray spectral variability of Seyfert 2 galaxies

Variability across the electromagnetic spectrum is a property of AGN that can help constraining the physical properties of these galaxies. This is the third of a serie of papers with the aim of studying the X-ray variability of different families of AGN. The main purpose of this work is to investigate the variability pattern in a sample of optically selected type 2 Seyfert galaxies. We use the 26 Seyferts in the Veron-Cetty and Veron catalogue with data available from Chandra and/or XMM-Newton public archives at different epochs, with timescales ranging from a few hours to years. All the spectra of the same source are simultaneously fitted and we let different parameters to vary in the model. Whenever possible, short-term variations and/or long-term UV flux variations are studied. We divide the sample in Compton-thick, Compton-thin, and changing-look candidates. Short-term variability at X-rays is not found. From the 25 analyzed sources, 11 show long-term variations; eight (out of 11) are Compton-thin, one (out of 12) is Compton-thick, and the two changing-look candidates are also variable. The main driver for the X-ray changes is related to the nuclear power (nine cases), while variations at soft energies or related with absorbers at hard X-rays are less common, and in many cases these variations are accompained with variations of the nuclear continuum. At UV frequencies nuclear variations are nor found. We report for the first time two changing-look candidates, MARK273 and NGC7319. A constant reflection component located far away from the nucleus plus a variable nuclear continuum are able to explain most of our results; the Compton-thick candidates are dominated by reflection, which supresses their continuum making them seem fainter, and not showing variations, while the Compton-thin and changing-look candidates show variations.Comment: Accepted for publication in A&

Reversible Graphene decoupling by NaCl photo-dissociation

We describe the reversible intercalation of Na under graphene on Ir(111) by photo-dissociation of a previously adsorbed NaCl overlayer. After room temperature evaporation, NaCl adsorbs on top of graphene forming a bilayer. With a combination of electron diffraction and photoemission techniques we demonstrate that the NaCl overlayer dissociates upon a short exposure to an X-ray beam. As a result, chlorine desorbs while sodium intercalates under the graphene, inducing an electronic decoupling from the underlying metal. Low energy electron diffraction shows the disappearance of the moir\'e pattern when Na intercalates between graphene and iridium. Analysis of the Na 2p core-level by X-ray photoelectron spectroscopy shows a chemical change from NaCl to metallic buried Na at the graphene/Ir interface. The intercalation-decoupling process leads to a n-doped graphene due to the charge transfer from the Na, as revealed by constant energy angle resolved X-ray photoemission maps. Moreover, the process is reversible by a mild annealing of the samples without damaging the graphene

Polymerase chain reaction detection of rabbit DNA in food and animal feed

[EN] A polymerase chain reaction (PCR) based on oligonucleotide primers targeting the mitochondrial 12S rRNA gene was developed for the specific identification of rabbit DNA (Oryctolagus cuniculus) in food and feedstuffs. The specificity of the primers was verified by PCR analysis of DNA from 32 non-target species including mammals, birds, fish, and plant species. Analysis of experimental mixtures demonstrated the presence of rabbit-derived materials in the range of 0.1-100%. Prolonged heat treatment (up to 133ºC for 20 min at 300 kPa) applied to rabbit muscle/oats binary mixtures did not affect the performance of the method, which could therefore be said to be very useful for the accurate identification of rabbit materials in products submitted to denaturing technologies when other methods are not suitable.This study was supported by Grant Nº. AGL 2007-60077 from the Spanish Ministerio de Educación y Ciencia and the Programa de Vigilancia Sanitaria S-0505/AGR/000265 of the Comunidad de Madrid (Spain). Irene Martín is the recipient of a fellowship from the Universidad Complutense de Madrid (Spain). Violeta Fajardo and María Rojas are recipients of fellowships from the Ministerio de Educación y Ciencia (Spain).Martín, I.; García, T.; Fajardo, V.; Rojas, M.; Pegels, N.; Hernández, P.; González, I.... (2009). Polymerase chain reaction detection of rabbit DNA in food and animal feed. World Rabbit Science. 17(1):27-34. doi:10.4995/wrs.2009.667273417

Balance and Postural Control Assess in Elite Ice Skaters

Análisis de curvas de fuerza muscular en patinadores de élite contando con el apoyo de sistemas de soporte a la decisión y técnicas de descubrimiento de conocimiento

Aplicación de TIG en la generación de indicadores de calidad ambiental de sistemas playa-dunas

Se presentan resultados parciales del subproyecto “Ecosistemas y Biodiversidad: vigilancia de espacios arenosos protegidos de Canarias y África”, incluido en el 'Programa para el desarrollo de redes tecnológicas y de aplicación de datos de teledetección en África Occidental', TELECAN (MAC/3/C181), financiado por el Programa de Cooperación Transnacional Madeira-Azores-Canarias (MAC) 2007/2013. El objetivo principal era definir, mediante el uso de imágenes de satélite, indicadores de calidad ambiental para sistemas playa-dunas, al ser éstos espacios fundamentales en el desarrollo socio-económico de estos territorios, dado su atractivo turístico. En este trabajo se presentan los resultados obtenidos para una de las áreas piloto, Maspalomas (Gran Canaria, islas Canarias). Los indicadores se obtuvieron mediante el procesado de imágenes del satélite WorldView-2, con validación, en 2013, mediante campañas marinas. Asimismo, se utilizaron imágenes de archivo, correspondientes a los años 2010, 2011 y 2012. Estos indicadores se basaron en variables relacionadas con las características físicas y biológicas de las aguas litorales y de las playas y dunas. Los resultados indican una calidad, por lo general, alta y muy alta, tanto para el medio terrestre como para el marino, con superficies dentro de estas categorías del 20,3% y 75,3% y del 26,1% y 70,6%, respectivamente.Esta es una contribución del 'Programa para el desarrollo de redes tecnológicas y de aplicación de datos de teledetección en África Occidental', TELECAN (MAC/3/C181), financiado por el Programa de Cooperación Transnacional Madeira-Azores-Canarias (MAC) 2007/2013

An erbium(III)-based NIR emitter with a highly conjugated ß-diketonate for blue-region sensitization

The sensitization of lanthanide complexes in the visible region is of particular interest for practical applications such as labeling, biological analysis and optoelectronics. A visible-light sensitized Er3+complex based on the use of a highly conjugated ß-diketonate (1, 3-di(2-naphthyl)-1, 3-propanedione, Hdnm) and 5-nitro-1, 10-phenanthroline (5NO2phen) as an ancillary ligand, [Er(dnm)3(5NO2phen)], has been synthesized, fully characterized and its photophysical properties have been investigated. Suitably expanded p-conjugation in the complex molecule makes the excitation window red-shifted to the visible region (up to 550 nm). Efficient energy transfer by antenna effect results in 1.53 µm emission from the Er3+ion

On the kinematics of the neutron star low mass X-ray binary Cen X-4

We present the first determination of the proper motion of the neutron star low mass X-ray binary {Cen X-4} measured from relative astrometry of the secondary star using optical images at different epochs. We determine the Galactic space velocity components of the system and find them to be significantly different from the mean values that characterize the kinematics of stars belonging to the halo, and the thin and the thick disc of the Galaxy. The high metallicity of the secondary star of the system rules out a halo origin and indicates that the system probably originated in the Galactic disc. A statistical analysis of the galactocentric motion revealed that this binary moves in a highly eccentric ($e\simeq 0.85\pm0.1$) orbit with an inclination of $\simeq 110^\circ$ to the Galactic plane. The large Galactic space velocity components strongly support that a high natal kick as a result of a supernova explosion could have propelled the system into such an orbit from a birth place in the Galactic disc. The high Li abundance in the secondary, comparable to that of stars in star forming regions and young stellar clusters like the Pleiades, may suggest a relatively recent formation of the system. Following the orbit backwards in time, we found that the system could have been in the inner regions of the Galactic disc $\sim$100--200 Myr ago. The neutron star might have formed at that moment. However, we cannot rule out the possibility that the system formed at a much earlier time if a Li production mechanism exists in this LMXB.Comment: 6 pages, 4 figures, accepted for publication in A&

Group 10 Metal Benzene-1,2-dithiolate Derivatives in the Synthesis of Coordination Polymers Containing Potassium Countercations

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/abs/10.1021/acs.inorgchem.7b01775The use of theoretical calculations has allowed us to predict the coordination behavior of dithiolene [M(SC6H4S)2]2- (M = Ni, Pd, Pt) entities, giving rise to the first organometallic polymers {[K2(μ-H2O)2][Ni(SC6H4S)2]}n and {[K2(μ-H2O)2(thf)]2[K2(μ-H2O)2(thf)2][Pd3(SC6H4S)6]}n by one-pot reactions of the corresponding d10 metal salts, 1,2-benzenedithiolene, and KOH. The polymers are based on σ,π interactions between potassium atoms and [M(SC6H4S)2]2- (M = Ni, Pd) entities. In contrast, only σ interactions are observed when the analogous platinum derivative is used instead, yielding the coordination polymer {[K2(μ-thf)2][Pt(SC6H4S)2]}nThis work was supported in part by the MICINN (grants MAT2016-77608-C3-1-P and MAT2016-75883-C2-1-P), Generalitat Valenciana (PrometeoII/2014/076), and ISIC. J.I.M. acknowledges financial support by the “Ramon y Cajal ́ ” Program of MINECO (RYC-2015-17730