The quasar main sequence and its potential for cosmology

The main sequence offers a method for the systematization of quasar spectral properties. Extreme FeII emitters (or extreme Population A, xA) are believed to be sources accreting matter at very high rates. They are easily identifiable along the quasar main sequence, in large spectroscopic surveys over a broad redshift range. The very high accretion rate makes it possible that massive black holes hosted in xA quasars radiate at a stable, extreme luminosity-to-mass ratio. After reviewing the basic interpretation of the main sequence, we report on the possibility of identifying virial broadening estimators from low-ionization line widths, and provide evidence of the conceptual validity of redshift-independent luminosities based on virial broadening for a known luminosity-to-mass ratio.Comment: 5 pages, 2 figures, contribution presented at the IAU Symposium 356, Nuclear Activity in Galaxies Across Cosmic Time, held in Addis Ababa, Ethiopia, on Oct. 7-11, 2019. M. Povic et al. (Eds.

Female Institutional Directors on Boards and Firm Value

The aim of this research is to examine what impact female institutional directors on boards have on corporate performance. Previous research shows that institutional female directors cannot be considered as a homogeneous group since they represent investors who may or may not maintain business relations with the companies on whose corporate boards they sit. Thus, it is not only the effect of female institutional directors as a whole on firm value that has been analysed, but also the impact of pressure-resistant female directors, who represent institutional investors (investment, pension and mutual funds) that only invest in the company, and do not maintain a business relation with the firm. We hypothesize that there is a non-linear association, specifically quadratic, between institutional and pressure-resistant female directors on boards and corporate performance. Our results report that female institutional directors on boards enhance corporate performance, but when they reach a certain threshold on boards (11.72 %), firm value decreases. In line with female institutional directors, pressure-resistant female directors on boards also increase firm value, but only up to a certain figure (12.71 % on boards), above which they have a negative impact on firm performance. These findings are consistent with an inverted U-shaped relationship between female institutional directors and pressure-resistant female directors and firm performance

Single and blended models for day-ahead photovoltaic power forecasting

Solar power forecasts are gaining continuous importance as the penetration of solar energy into the grid rises. The natural variability of the solar resource, joined to the difficulties of cloud movement modeling, endow solar power forecasts with a certain level of uncertainty. Important efforts have been carried out in the field to reduce as much as possible the errors. Various approaches have been followed, being the predominant nowadays the use of statistical techniques to model production. In this study, we have performed a comparison study between two extensively used statistical techniques, support vector regression (SVR) machines and random forests, and two other techniques that have been scarcely applied to solar forecasting, deep neural networks and extreme gradient boosting machines. Best results were obtained with the SVR technique, showing a nRMSE of 22.49%. To complete the assessment, a weighted blended model consisting on an average weighted combination of individual predictions was created. This blended model outperformed all the models studied, with a nRMSE of 22.24%. © Springer International Publishing AG 2017

Extreme Quasars as Distance Indicators in Cosmology

Quasars accreting matter at very high rates (known as extreme Population A [xA] quasars, possibly associated with super-Eddington accreting massive black holes) may provide a new class of distance indicators covering cosmic epochs from present day up to less than 1 Gyr from the Big Bang. At a more fundamental level, xA quasars are of special interest in studies of the physics of AGNs and host galaxy evolution. However, their observational properties are largely unknown. xA quasars can be identified in relatively large numbers from major optical surveys over a broad range of redshifts, and efficiently separated from other type-1 quasars thanks to selection criteria defined from the systematically-changing properties along the quasars main sequence. It has been possible to build a sample of ~250 quasars at low and intermediate redshift, and larger samples can be easily selected from the latest data releases of the Sloan Digital Sky Survey. A large sample can clarify the main properties of xA quasars which are expected—unlike the general population of quasars—to radiate at an extreme, well-defined Eddington ratio with small scatter. As a result of the small scatter in Eddington ratio shown by xA quasars, we propose a method to derive the main cosmological parameters based on redshift-independent “virial luminosity” estimates from measurements of emission line widths, roughly equivalent to the luminosity estimates based from line width in early and late type galaxies. A major issue related to the cosmological application of the xA quasar luminosity estimates from line widths is the identification of proper emission lines whose broadening is predominantly virial over a wide range of redshift and luminosity. We report on preliminary developments using the AlIIIλ1860 intermediate ionization line and the Hydrogen Balmer line Hβ as virial broadening estimators, and we briefly discuss the perspective of the method based on xA quasars. © Copyright © 2020 Dultzin, Marziani, de Diego, Negrete, Del Olmo, Martínez-Aldama, D'Onofrio, Bon, Bon and Stirpe.This research is part of the projects 176001-Astrophysical spectroscopy of extragalactic objects and 176003-Gravitation and the large scale structure of the Universe, funded by Ministry of Education, Science and Technological Development of the Republic of Serbia.Peer reviewe

Programa de investigación en el aula : adaptación y puesta en práctica del programa de pensamiento productivo de Covington para la mejora del pensamiento creativo, razonamiento general y motivación hacia el aprendizaje en la Secundaria Obligatoria

Insertar en el currículum de la Enseñanza Secundaria Obligatoria un programa de intervención psicopedagógica encaminado a la mejora de las habilidades cognitivas. Conocer y analizar el programa de pensamiento productivo y otros afines, con vistas a su aplicación práctica en el aula. Reelaborar dicho programa, adecuarlo para que el planteamiento y el contenido sean más significativos para el alumno. Realizar actividades complementarias encaminadas a dar consistencia a la mejora del pensamiento divergente y que sirvan para reforzar los procesos puestos en juego. Contrastar experimentalmente los datos obtenidos en los aspectos de razonamiento, pensamiento divergente y motivación hacia el aprendizaje. Divulgar los resultados obtenidos. Alumnos de séptimo de EGB del curso 1991-92 de colegios de Calahorra (La Rioja): 1 grupo experimental de 19 alumnos del C.P. 'Angel Oliván'; 2 grupos experimentales de 17 y 18 alumnos del C.P. 'Quintiliano'; 1 grupo de control de 18 alumnos del C.P. 'San Andrés' y 2 grupos de control de 35 y 37 alumnos del C.P. 'Aurelio Prud'. Con el fin de ofrecer a los alumnos de EGB materiales alternativos para incrementar la motivación, creatividad y razonamiento, un grupo de profesores seleccionó el programa Covington. Dicho programa fue revisado y se reelaboraron sus textos, contenidos y dibujos. Se construyó un cuaderno de trabajo para el alumno y se reorganizó el cuaderno para el profesor. El grupo de trabajo fue estructurado en comisiones encargadas de las distintas tareas: dibujar, reelaborar textos, enmaquetar, elaborar los cuadernos, evaluación experimental, evaluación cualitativa y elaboración de la memoria. El programa se puso en práctica durante el curso escolar 1991-92. Programa de pensamiento productivo de Covington. Los resultados experimentales no reflejan el incremento de la motivación, del razonamiento ni del pensamiento divergente de los alumnos. No obstante, los profesores constataron un gran interés y participación en las sesiones de trabajo, así como una mejora en la identificación de los problemas planteados. También se apreciaron una serie de limitaciones que entorpecen la generalización de las estrategias aprendidas en el programa, similares a las encontradas en otros programas existentes en el mercado. La labor del profesorado debe favorecer el aprendizaje y el uso de muchas estrategias. El programa merece la aprobación de los profesores participantes y lo consideran válido y de provecho para ser incluido en el currículum, sobre todo por las posibilidades que ofrece a los docentes entusiastas, a los que inquieta conseguir alumnos reflexivos, creativos y lúdicos.Ministerio Educación CIDEBiblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San Agustín, 5 - 3 Planta; 28014 Madrid; Tel. +34917748000; Fax +34917748026; [email protected]

Patients with Crohn's disease have longer post-operative in-hospital stay than patients with colon cancer but no difference in complications' rate

BACKGROUNDRight hemicolectomy or ileocecal resection are used to treat benign conditions like Crohn's disease (CD) and malignant ones like colon cancer (CC).AIMTo investigate differences in pre- and peri-operative factors and their impact on post-operative outcome in patients with CC and CD.METHODSThis is a sub-group analysis of the European Society of Coloproctology's prospective, multi-centre snapshot audit. Adult patients with CC and CD undergoing right hemicolectomy or ileocecal resection were included. Primary outcome measure was 30-d post-operative complications. Secondary outcome measures were post-operative length of stay (LOS) at and readmission.RESULTSThree hundred and seventy-five patients with CD and 2,515 patients with CC were included. Patients with CD were younger (median = 37 years for CD and 71 years for CC (P < 0.01), had lower American Society of Anesthesiology score (ASA) grade (P < 0.01) and less comorbidity (P < 0.01), but were more likely to be current smokers (P < 0.01). Patients with CD were more frequently operated on by colorectal surgeons (P < 0.01) and frequently underwent ileocecal resection (P < 0.01) with higher rate of de-functioning/primary stoma construction (P < 0.01). Thirty-day post-operative mortality occurred exclusively in the CC group (66/2515, 2.3%). In multivariate analyses, the risk of post-operative complications was similar in the two groups (OR 0.80, 95%CI: 0.54-1.17; P = 0.25). Patients with CD had a significantly longer LOS (Geometric mean 0.87, 95%CI: 0.79-0.95; P < 0.01). There was no difference in re-admission rates. The audit did not collect data on post-operative enhanced recovery protocols that are implemented in the different participating centers.CONCLUSIONPatients with CD were younger, with lower ASA grade, less comorbidity, operated on by experienced surgeons and underwent less radical resection but had a longer LOS than patients with CC although complication's rate was not different between the two groups