The central parsecs of M87: jet emission and an elusive accretion disc

We present the first simultaneous spectral energy distribution (SED) of M87 core at a scale of 0.4 arcsec ($\sim 32\, \rm{pc}$) across the electromagnetic spectrum. Two separate, quiescent, and active states are sampled that are characterized by a similar featureless SED of power-law form, and that are thus remarkably different from that of a canonical active galactic nuclei (AGN) or a radiatively inefficient accretion source. We show that the emission from a jet gives an excellent representation of the core of M87 core covering ten orders of magnitude in frequency for both the active and the quiescent phases. The inferred total jet power is, however, one to two orders of magnitude lower than the jet mechanical power reported in the literature. The maximum luminosity of a thin accretion disc allowed by the data yields an accretion rate of $< 6 \times 10^{-5}\, \rm{M_\odot \, yr^{-1}}$, assuming 10% efficiency. This power suffices to explain M87 radiative luminosity at the jet-frame, it is however two to three order of magnitude below that required to account for the jet's kinetic power. The simplest explanation is variability, which requires the core power of M87 to have been two to three orders of magnitude higher in the last 200 yr. Alternatively, an extra source of power may derive from black hole spin. Based on the strict upper limit on the accretion rate, such spin power extraction requires an efficiency an order of magnitude higher than predicted from magnetohydrodynamic simulations, currently in the few hundred per cent range.Comment: 18 pages, 6 figures. Accepted for publication in MNRA

OTELO survey: optimal emission-line flux determination with OSIRIS/GTC

Emission-line galaxies are important targets for understanding the chemical evolution of galaxies in the universe. Deep, narrow-band imaging surveys allow to detect and study the flux and the equivalent widths (EW) of the emission line studied. The present work has been developed within the context of the OTELO project, an emission line survey using the Tunable Filters (TF) of OSIRIS, the first generation instrument on the GTC 10.4m telescope located in La Palma, Spain, that will observe through selected atmospheric windows relatively free of sky emission lines. With a total survey area of 0.1 square degrees distributed in different fields, reaching a 5 \sigma depth of 10^-18 erg/cm^2/s and detecting objects of EW < 0.3 A, OTELO will be the deepest emission line survey to date. As part of the OTELO preparatory activities, the objective of this study is to determine the best combination of sampling and full width at half maximum (FWHM) for the OSIRIS tunable filters for deblending H\alpha from [NII] lines by analyzing the flux errors obtained. We simulated the OTELO data by convolving a complete set of synthetic HII galaxies in EW with different widths of the OSIRIS TFs. We estimated relative flux errors of the recovered H\alpha and [NII]6583 lines. We found that, for the red TF, a FWHM of 12 A and a sampling of 5 A is an optimal combination that allow deblending H\alpha from the [NII]6583 line with a flux error lower than 20%. This combination will allow estimating SFRs and metallicities using the H\alpha flux and the N2 method, respectively.Comment: 16 pages, 9 figures. Some authors added. Accepted for publication in PAS

Prevalence of Geographic Tongue in Chilean Children between 7 and 10 Years of Age

Indexación: Web of Science; Scielo.RESUMEN: El objetivo del estudio fue determinar la prevalencia de lengua geográfica y evaluar su asociación con el estrés emocional, irritación crónica, lengua fisurada y tipo de establecimiento educacional, en niños de 7 a 10 años de edad en la ciudad de Viña del Mar, Chile. De un total de 27.234 escolares, cursando 2 a 5 año básico, pertenecientes a colegios de la ciudad de Viña del Mar, Chile, se examinaron 436 niños.Se realizó un estudio descriptivo transversal de alumnos provenientes de tres tipos de establecimientos educacionales diferentes: particular, particular con subvención del estado de Chile y municipalizado. Las variables estudiadas fueron edad, sexo y establecimiento educacional. Adicionalmente, en los alumnos con lengua geográfica y 23 alumnos sin este diagnóstico se evaluó la presencia de lengua fisurada, irritación lingual crónica y estrés emocional. Se determinó la prevalencia mediante el cálculo de una proporción, las variables discretas se analizaron mediante Chi-cuadrado de Pearson o la prueba de Fisher y para determinar medidas de asociación con lengua geográfica se realizó regresión logística binaria, considerándose significativo un p<0,05. De los 436 niños, 23 presentaron lengua geográfica, evidenciando una prevalencia de 5,28%, con un IC 95% de 3,37% a 7,81%. No se evidenciaron diferencias respecto al sexo, edad ni tipo de establecimiento educacional. No se determinaron factores asociados a lengua geográfica. La prevalencia de LG determinada es similar a otros estudios que abarcan la misma población de rangos etarios. Al igual que en otros estudios no se pudo demostrar que el estrés emocional, irritación crónica, lengua fisurada y tipo de establecimiento educacional constituyeron factores asociados a la presencia de lengua geográfica.ABSTRACT: The aim of this study was to determine the prevalence of geographic tongue and evaluate its association with emotional stress, chronic irritation, fissured tongue and type of educational establishment, in children between 7 and 10 years of age, in the city of Viña del Mar, Chile. From a total of 27,234 students attending 2nd through 5th grade, we examined 436 children. A descriptive study of students was carried out from three different educational institutions: private, private with state funding and public schools. The variables studied were age, sex and the educational establishment the children attended. Additionally in the students with geographic tongue and in 23 students without this diagnosis, we evaluated the presence of fissured tongue, tongue irritation and chronic emotional stress. Prevalence was determined by calculating ratio, discrete variables were analyzed using Pearson Chi-square test or Fisher, and in order to determine association measures with geographic tongue, binary logistic regression was considered significant at p <0.05. Of the 436 children, 23 had geographic tongue, showing a prevalence of 5.28% with a 95% CI 3.37% to 7.81%. No differences regarding sex, age and type of educational establishment were found. No factors associated with geographic tongue were determined. The prevalence of the LG is similar to other studies covering the same age ranges. Furthermore, and as in other works, our study did not to show that emotional stress, chronic irritation, fissured tongue and the type of educational establishment constituted factors associated with the presence of geographic tongue.http://ref.scielo.org/y3rcd

Hierarchical Up/Down Routing Architecture for Ethernet backbones and campus networks

We describe a new layer two distributed and scalable routing architecture. It uses an automatic hierarchical node identifier assignment mechanism associated to the rapid spanning tree protocol. Enhanced up/down mechanisms are used to prohibit some turns at nodes to break cycles, instead of blocking links like the spannning tree protocol does. The protocol performance is similar or better than other turn prohibition algorithms recently proposed with lower complexity O(Nd) and better scalability. Simulations show that the fraction of prohibited turns over random networks is less than 0.2. The effect of root bridge election on the performance of the protocol is limited both in the random and regular networks studied. The use of hierarchical, tree-descriptive addresses simplifies the routing, and avoids the need of all nodes having a global knowleddge of the network topology. Routing frames through the hierarchical tree at very high speed is possible by progressive decoding of frame destination address, without routing tables or port address learning. Coexistence with standard bridges is achieved using combined devices: bridges that forward the frames having global destination MAC addresses as standard bridges and frames with local MAC frames with the proposed protocol.Publicad