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&

X-ray spectral variability of LINERs selected from the Palomar sample

Variability is a general property of active galactic nuclei (AGN). At X-rays, the way in which these changes occur is not yet clear. In the particular case of low ionisation nuclear emission line region (LINER) nuclei, variations on months/years timescales have been found for some objects, but the main driver of these changes is still an open question. The main purpose of this work is to investigate the X-ray variability in LINERs, including the main driver of such variations, and to search for eventual differences between type 1 and 2 objects. We use the 18 LINERs in the Palomar sample with data retrieved from Chandra and/or XMM-Newton archives corresponding to observations gathered at different epochs. All the spectra for the same object are simultaneously fitted in order to study long term variations. The nature of the variability patterns are studied allowing different parameters to vary during the spectral fit. Whenever possible, short term variations from the analysis of the light curves and UV variability are studied.Comment: 49 pages, accepted. arXiv admin note: text overlap with arXiv:1305.222

A new battery-charging method suggested by molecular dynamics simulations

Based on large-scale molecular dynamics simulations, we propose a new charging method that should be capable of charging a Lithium-ion battery in a fraction of the time needed when using traditional methods. This charging method uses an additional applied oscillatory electric field. Our simulation results show that this charging method offers a great reduction in the average intercalation time for Li+ ions, which dominates the charging time. The oscillating field not only increases the diffusion rate of Li+ ions in the electrolyte but, more importantly, also enhances intercalation by lowering the corresponding overall energy barrier.Comment: 11 pages, 5 figure

Valor nutricional de los ácidos grasos de los peces de agua dulce neotropicales Prochilodus magdalenae, Pseudoplatystoma magdaleniatum y Ageneiosus pardalis

This study aimed to determine the nutritional value of the fatty acids in the freshwater fish Prochilodus magdalenae, Pseudoplatystoma magdaleniatum and Ageneiosus pardalis during dry and wet Neotropical seasons with the view to generate useful information for nutrition and sustainable commercial exploitation. The analysis of fatty acids was performed by gas chromatography–mass spectrometry and the nutritional value was calculated using five estimators: n-6/n-3 ratio, unsaturation index (UI), atherogenicity index (AI), thrombogenicity index (TI) and ratio of hypocholesterolemic/hypercholesterolemic (h/H) fatty acids. A different number of fatty acids (P. magdaleniatum = 50, P. magdalenae = 41, and A. pardalis = 32) was identified for each species and the average abundance percentages were different in the two seasons (p < 0.05). Prochilodus magdalenae and P. magdaleniatum showed healthy n-6/n-3 ratios (1.04 and 2.72) in the different seasons. Although the three species showed low values of UI (0.37–0.63), the remaining nutritional indexes were within the healthy range (AI: 0.04–0.70, TI: 0.66–1.07, h/H: 0.80 – 24.40). Multivariate analysis showed similar healthy nutritional values for the species, with exception of P. magdaleniatum.En este estudio se determinó el valor nutricional de ácidos grasos presentes en las especies P. magdaleniatum, P. magdalenae y A. pardalis en los periodos lluvioso y seco, con el fin de generar información útil para una nutrición saludable y una explotación comercial sostenible. El análisis de los ácidos grasos se realizó por CG-EM y el valor nutricional se estimó mediante relación n-6/n-3, índices de insaturación (II), aterogenicidad (IA), trombogenicidad (IT) y relación de ácidos grasos hipocolesterolémicos/hipercolesterolémicos (h/H). Se identificaron números diferentes de ácidos grasos en cada especie (P. magdaleniatum = 50, P. magdalenae = 41 and A. pardalis = 32) y las medias de los porcentajes mayoritarios fueron diferentes en los dos periodos (p < 0,05). Las especies P. magdalenae y P. magdaleniatum mostraron relaciones n-6/n-3 saludables (1,04 y 2,72) en periodos diferentes. Aunque las tres especies mostraron valores II bajos (0,37-0,63), los demás índices IA (0,04-0,70), TI (0,66-1,07) y h/H (0,80 – 24,40) están dentro del rango saludable. El análisis multivariante mostró valores nutricionales similares en dos especies excepto P. magdaleniatum

Finite-dimensional Nichols algebras over dual Radford algebras

For n, m ∈ N, let Hn,m be the dual of the Radford algebra of dimension n 2m. We present new finite-dimensional Nichols algebras arising from the study of simple Yetter-Drinfeld modules over Hn,m. Along the way, we describe the simple objects in Hn,m Hn,m YD and their projective envelopes. Then, we determine those simple modules that give rise to finite-dimensional Nichols algebras for the case n = 2. There are 18 possible cases. We present by generators and relations the corresponding Nichols algebras on five of these eighteen cases. As an application, we characterize finite-dimensional Nichols algebras over indecomposable modules for n = 2 = m and n = 2, m = 3, which recovers some results of the second and third author in the former case, and of Xiong in the latter.Fil: Bagio, D.. Universidade Federal de Santa Maria; BrasilFil: García, Gastón Andrés. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Matemáticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Jury Giraldi, Joao Matheus. Universidade Federal de Santa Maria; BrasilFil: Márquez, O.. Universidade Federal de Santa Maria; Brasi

Quantum mechanical spectral engineering by scaling intertwining

Using the concept of spectral engineering we explore the possibilities of building potentials with prescribed spectra offered by a modified intertwining technique involving operators which are the product of a standard first-order intertwiner and a unitary scaling. In the same context we study the iterations of such transformations finding that the scaling intertwining provides a different and richer mechanism in designing quantum spectra with respect to that given by the standard intertwiningComment: 8 twocolumn pages, 5 figure

Conocimientos y actitudes ante la Voluntad Anticipada en profesionales de la salud del Centro Médico “Lic. Adolfo López Mateos”, Toluca, México

Introducción: La Voluntad Anticipada es una declaración mediante la cual una persona mayor de edad, con capacidad mental suficiente y libremente, expone las instrucciones que se deben tener en cuenta respecto a la atención sanitaria que desea recibir en situaciones en las cuales no pueda ya expresar personalmente su voluntad. Objetivo: Determinar el nivel de conocimientos y actitudes que tienen los profesionales de la salud de Centro Médico “Lic. Adolfo López Mateos” con respecto a la Ley de Voluntad Anticipada del Estado de México. Método y materiales: Se aplicaron 265 encuestas que incluían el conocimiento y la actitud que tienen los profesionales de la salud sobre la Ley de Voluntad Anticipada del Estado de México. Resultados: El grupo mayoritario abarcó de 25-29 años con el 31%, el turno mayoritario fue el de la Jornada Especial con 34%, el 60% de los encuestados fueron mujeres y 40% hombres, el 94% no había leído la Ley de Voluntad Anticipada inscrita en la gaceta oficial del Gobierno del Estado de México y el 6% restante respondió afirmativamente. Conclusiones: La mayoría de los y las profesionales de salud refirieron no conocer la Ley inscrita en la gaceta oficial, lo que significa que hace falta difusión y promoción del tema; a pesar de eso, tuvieron una posición favorable hacia la voluntad anticipada y demostraron tener noción sobre lo tratad

First Report of Soybean (Glycine max) Disease Caused by Pseudomonas aeruginosa in Cuba

Soybean (Glycine max L.) has become one of the most widely consumed foods, however diseases caused by microorganisms can affect yields and seed quality. In March 2015, during routine survey in a soybean growing area in Pinar del Rio province, Cuba; disease symptoms were observed in some leaves. These included water-soaked necrotic spots with surrounded chlorotic halos, especially on the margins of the leaves. To identify the possible pathogens involved, leaves were disinfected with tap water, 70% ethanol and were rinsed with sterile distilled water. Small segments from diseased tissue were macerated in sterile 0.85% NaCl solution, decimal dilutions were performed and 20 µL aliquots were streaked onto King´s B medium (KB). After 24 hours of incubation at 28 oC, a fluorescent pseudomonad was isolated. Colonies were round, smooth and produced yellowish-green diffusible pigments on KB. Physiological and morphological characteristics were determined using standard microbiological techniques (Schaad et al., 200..