Modelling the disk atmosphere of the low mass X-ray binary EXO 0748-676

Low mass X-ray binaries exhibit ionized emission from an extended disk atmosphere that surrounds the accretion disk. However, its nature and geometry is still unclear. In this work we present a spectral analysis of the extended atmosphere of EXO 0748-676 using high-resolution spectra from archival XMM-Newton observations. We model the RGS spectrum that is obtained during the eclipses. This enables us to model the emission lines that come only from the extended atmosphere of the source, and study its physical structure and properties. The RGS spectrum reveals a series of emission lines consistent with transitions of O VIII, O VII, Ne IX and N VII. We perform both Gaussian line fitting and photoionization modelling. Our results suggest that there are two photoionization gas components, out of pressure equilibrium with respect to each other. One with ionization parameter of 2.5 and a large opening angle, and one with 1.3. The second component is possibly covering a smaller fraction of the source. From the density diagnostics of the O vii triplet using photoionization modelling, we detect a rather high density plasma of > 10^13 cm^-3 for the lower ionization component. This latter component also displays an inflow velocity. We propose a scenario where the high ionization component constitutes an extended upper atmosphere of the accretion disk. The lower ionization component may instead be a clumpy gas created from the impact of the accretion stream with the disk.Comment: A&A accepted, 10 pages, 9 figure

El tipo de centro educativo (público o privado) sobre el léxico disponible: análisis de cada subgrupo

Los estudios de disponibilidad léxica en español han avanzado notablemente en las últimas décadas (López González, 2014). Una de las variables tradicionales en los estudios herederos del Proyecto Panhispánico de Disponibilidad Léxica es el tipo de centro escolar (público o privado). El objetivo de esta comunicación es doble: por una parte, mostrar la relación que existe entre el tipo de centro educativo y el léxico aportado por los informantes en los diferentes centros de interés; y, por otra parte, conocer las características de cada subgrupo (centro público y privado). La muestra de estudio está formada por 400 estudiantes preuniversitarios sevillanos, de los cuales 297 se encontraban cursando estudios en centros públicos y 103 en centros privados. La metodología de recogida y procesamiento de los datos sigue las pautas del Proyecto Panhispánico de Disponibilidad Léxica. Los resultados corroboran los hallazgos de estudios previos donde la media de palabras registrada en los centros privados (319,50 palabras) es superior a la de centros públicos (308,60 palabras). En cuanto a las diferencias entre cada subgrupo, se constata que los centros privados se sitúan en zonas urbanas y acogen a poblaciones de un nivel sociocultural más alto, por lo que se produce una relación significativa a nivel estadístico entre el tipo de centro, la clase social (alta, media o baja) y la zona (urbana o rural). En ambos grupos, el nivel sociocultural influye en el número de palabras en general pero al realizar un análisis más pormenorizado por centros de interés, se detecta que la relación no es significativa en todos los centros. Los hallazgos han demostrado que el léxico presentado por los informantes está muy marcado por su contexto social: centro educativo, clase social y zona. Viendo esas diferencias que se producen, desde las escuelas se deberían desarrollar proyectos lingüísticos de centro que ayuden a mejorar la competencia lingüística desde todas las áreas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A highly-ionized absorber as a new explanation for the spectral changes during dips from X-ray binaries

Until now, the spectral changes observed from persistent to dipping intervals in dipping low-mass X-ray binaries were explained by invoking progressive and partial covering of an extended emission region. Here, we propose a novel and simpler way to explain these spectral changes, which does not require any partial covering and hence any extended corona, and further has the advantage of explaining self-consistently the spectral changes both in the continuum and the narrow absorption lines that are now revealed by XMM-Newton. In 4U 1323-62, we detect Fe XXV and Fe XXVI absorption lines and model them for the first time by including a complete photo-ionized absorber model rather than individual Gaussian profiles. We demonstrate that the spectral changes both in the continuum and the lines can be simply modeled by variations in the properties of the ionized absorber. From persistent to dipping the photo-ionization parameter decreases while the equivalent hydrogen column density of the ionized absorber increases. In a recent work (see Diaz Trigo et al. in these proceedings), we show that our new approach can be successfully applied to all the other dipping sources that have been observed by XMM-Newton.Comment: 5 pages, 5 figures, to appear in the proceedings of "The X-ray Universe 2005", San Lorenzo de El Escorial (Spain), 26-30 September 200

Virtual tools in the concept of reading of future teachers: a lexical exploration

New forms of reading have emerged recently, and virtual tools and environments have been developed to promote reading. Initial teacher training must be up to date to train good mediators. Therefore, this research analyses the presence of digital tools in the concept of reading of future teachers. The data has been collected through a lexical availability test to explore the centre of interest “Reading” and a sociodemographic questionnaire with questions related to reading and knowledge of languages. 520 students from the degrees in Early Childhood and Primary Education at the University of Malaga have participated. Dispogen has been used to process the available lexicon and the SPSS package has been used for the statistical analysis. In addition, clusters have been obtained from the lexicon related to digital tools using the DispoGrafo tool. The results show a motivation to read on social networks and a rootedness of the lexicon referred to digital media: e-book, Kindle, specifying format: PDF, Word, and type of reading: digital review, Academic Google, but they do not demonstrate a lexical domain for the formation of new readers

Relativistic Fe line emission and highly photoionized absorption in GROJ1655-40

We report on two XMM-Newton and simultaneous INTEGRAL observations of the microquasar GRO J1655-40 during its 2005 outburst. The source was most probably in its high-soft state during both observations. There is evidence for the presence of both a relativistically broadened Fe line providing strong support for the existence of a spinning black hole, and a highly photo-ionized absorber. The photo-ionized absorber is responsible for strong K absorption lines of Fe XXV and Fe XXVI in the EPIC pn spectra. The parameters of the highly-ionized absorber were different during the two observations. A less ionized absorber is present in the second observation, where the 0.5–200 keV luminosity of GRO J1655-40 decreased by around a half. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55861/1/1008_ftp.pd

Preliminary study of the airborne pollen in the atmosphere of Puerto Ayora (Galapagos Islands, Ecuador)

Galapagos is an archipelago of volcanic islands located 972 km west from the continental Ecuador. They were declared by the UNESCO as a World Heritage Site and Biosphere Reserve due to their singular environmental value, where a third part of the native plants are endemic to this archipelago (Jaramillo et al., 2011). In spite of the numerous scientific studies carried out in Galapagos, there are not any aerobiological samplings being performed currently. The main objectives of this study were to install a pollen trap for detecting the presence of pollen in the atmosphere of Puerto Ayora (Santa Cruz, Galapagos Islands) and qualitatively identify the different pollen types detected during the studied period. A Durham (1946) gravimetric pollen trap was modified to turn it into a passive impact pollen trap based on Pla Dalmau (1957) modifications. It was placed on the roof of the Galapagos National School (Puerto Ayora, Santa Cruz Island) at a height of 15m above ground level. The samples were obtained by using silicone fluid as adhesive substance and glycerine gelatine as mounting mean. The pollen grains were counted in a surface of 14 x 48 mm in each sample. The pollen types were identified with the aid of the pollen guide of the Galapagos Island by Jaramillo & Trigo (2011) and the Charles Darwin Foundation pollen bank. Pollen types of endemic plants such as Darwiniothamnus sp., Passiflora foetida var. galapagensis Killip, Justicia galapagana Lindau and Castela galapageia Hook. f. were detected together with those of other native and introduced species. A high diversity of pollen types was detected, reflecting the particular vegetation of the island. This preliminary aerobiological information can be used as precedent for further studies on the pollination of native and introduced species of the Galapagos Islands, as well as for detecting possible allergic diseases in the population.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Revisiting university students' knowledge that involves basic differential equation questions

This study documents the extent to which university students utilize diverse representations and mathematical processes to interpret and respond to a set of questions that involves fundamental concepts in the study of differential equations. Results indicate that students' idea to solve a differential equation is reduced to the application of proper solution methods to a certain type of equation differential expressions. Thus, instructional activities should promote the students' use of several representation systems in which they can reflect on the various aspects associated with the concept itself, the solution methods, procedures, and the corresponding meaning and connections among those representations

Procesos conceptuales y cognitivos en la introducción de las ecuaciones diferenciales ordinarias vía la resolución de problemas

En este artículo se identifican y analizan los procesos cognitivos que desarrollan un grupo de estudiantes de primer curso de la licenciatura en Química mientras resuelven un problema diseñado como parte de un Módulo de Enseñanza para la introducción de las Ecuaciones Diferenciales Ordinarias (EDO). La conjugación de un escenario de resolución de problemas, con el uso de tecnología (la calculadora VoyageTM200) y la interacción entre estudiantes se revelan como una combinación que promueve y favorece el uso de procesos que contribuyen a la construcción del concepto de Ecuación Diferencial.This study aims to analyze cognitive processes that a group of first year Chemistry students exhibit while working on a task that involves dealing with a variation phenomenon. The task is part of a teaching module to introduce the study of Ordinary Differential Equations. The implementation of the module was based on combining problem solving activities, the use of a hand-held calculator and fostering a collaboration work among students. Results indicate that the participants recognized and valued a problem solving approach that led them to use various representations and strategies to construct the concept of Differential Equation

Conceptual and cognitive processes in the introduction of ordinary differential equations through problem solving

En este artículo se identifican y analizan los procesos cognitivos que desarrollan un grupo de estudiantes de primer curso de la licenciatura en Química mientras resuelven un problema diseñado como parte de un Módulo de Enseñanza para la introducción de las Ecuaciones Diferenciales Ordinarias (EDO). La conjugación de un escenario de resolución de problemas, con el uso de tecnología (la calculadora VoyageTM200) y la interacción entre estudiantes se revelan como una combinación que promueve y favorece el uso de procesos que contribuyen a la construcción del concepto de Ecuación Diferencial.This study aims to analyze cognitive processes that a group of first year Chemistry students exhibit while working on a task that involves dealing with a variation phenomenon. The task is part of a teaching module to introduce the study of Ordinary Differential Equations. The implementation of the module was based on combining problem solving activities, the use of a hand-held calculator and fostering a collaboration work among students. Results indicate that the participants recognized and valued a problem solving approach that led them to use various representations and strategies to construct the concept of Differential Equation