La concepción simple de la lectura en educación primaria: una revisión sistemática

La concepción simple de la lectura (CSL) es un modelo que trata de explicar la comprensión lectora (L) a partir de dos componentes básicos: la descodificación (D) y la comprensión del lenguaje (C). En los últimos años este modelo ha sido utilizado como base teórica para la toma de decisiones sobre el aprendizaje de la lectura en el sistema educativo de países como Reino Unido o Francia. La CSL ha sido criticada por distintos motivos. El primero, y más importante, es que D y C dejan sin explicar una parte importante de la varianza de los resultados de L. Esta parte podría ser del 50% o más, lo que indicaría que el modelo es incompleto y existe la posibilidad de que personas con una descodificación y comprensión del lenguaje normales obtengan malos resultados en comprensión lectora. También se ha señalado que los componentes del modelo están vagamente definidos, especialmente C, y que distintos autores los evalúan de formas diferentes. Otras críticas son que la relación entre sus componentes cambia con la edad y que no ha inspirado intervenciones pedagógicas de consideración. A pesar de estas observaciones, se considera que la CSL puede ser útil en educación ya que tiene características poco habituales en los modelos de comprensión lectora como su carácter evolutivo, el énfasis en la descodificación y su sencillez.The simple view of reading (SVR) is a model to explain reading comprehension (R) using two basic components: decoding (D) and language comprehension (C). In recent years this model has been employed as a theoretical base for decision making in the education system in countries such as United Kingdom or France. The SVR has been criticized for several reasons. The first, and most important, is that D and C cannot explain a substantial part of the variance of R results. This unexplained part could be 50% or even higher, which could mean that the model is not complete and that there is a possibility that people with normal decodification and language comprehension skills could perform badly in reading comprehension tasks. It has also been pointed out that the components of the model are loosely defined, particularly C, and that different researchers evaluate those components in different ways. Other criticisms are that the relation between the components of the model changes with age, and that it has not produced any relevant pedagogical interventions. In spite of these points, the SVR can be useful in educational work. It has some characteristics that are unusual in reading comprehension models: it is evolutionary, it places emphasis on decoding, and it is an easy to understand model

Coherent artifact and time-dependent polarization in amplified ultrafast erbium-doped fibre lasers

Mode-locked erbium-doped fibre lasers are ultrashort pulsed sources widely studied due to their versatility and multiple applications in the near infrared range. Here we present the experimental study of the emission of a passive mode-locked erbium-doped fibre laser with an amplification stage outside the cavity by means of Frequency Resolved Optical Gating (FROG) and spectral interferometry. Due to shot-to-shot instabilities, the FROG traces can be understood as the combination of two different traces, corresponding to the coherent artifact and the average pulse characteristics. We have modified a Principal Components Generalized Projections Algorithm, in order to make it able to retrieve efficiently both the coherent artifact and the average pulse. In addition, we study the temporal dependence of the polarization, showing that the pulses present time-dependent polarization with a stable spectral relative phase between the horizontal and vertical projections. Up to our knowledge, this is the first experimental study that shows the FROG measurements of unstable pulse trains associated with the coherent artifact and analyses the time-dependent polarization in ultrafast fibre lasers

Reading Comprehension Improvement for Spanish Students: A Meta- Analysis

Se realizó una revisión sistemática de intervenciones para la mejora de la comprensión lectora en español. Se incluyeron estudios realizados con alumnado en edad escolar con diseños experimentales o diseños cuasi-experimentales, que habían controlado la equivalencia de los grupos en comprensión lectora antes de la intervención. Se localizaron 39 estudios con los que se hizo un meta-análisis de efectos aleatorios obteniendo una estimación combinada del tamaño del efecto de 0.71. Se muestra la eficacia de las intervenciones basadas en estrategias de comprensión, como la identificación de ideas principales o la construcción de inferencias, y de las que combinan la enseñanza de estrategias con otros métodos como la motivación o la mejora de la descodificación. Solo dos estudios proporcionaron información sobre cómo se mantenían los resultados tiempo después de finalizar la intervención por lo que se considera que ése tendría que ser uno de los puntos a tener en cuenta en futuras investigaciones

Obstrucción por cuerpos extraños localizados en esófago : terapéutica endoscópica. Tres casos clínicos

Se presentan tres casos clínicos de obstrucción esofágica por cuerpos extraños en posición precardial que son extraídos por técnica endoscópica con fibroencloscopio flexible.Three clinical cases of oesophagus obstruction due to foreign bodies in precardial position are described. These-foreign bodies have been removed by endoscopical technic with flexible fiberscope

Response of alluvial systems to Late Pleistocene climate changes recorded by environmental magnetism in the Añavieja Basin (Iberian Range, NE Spain)

Environmental magnetic proxies were analyzed in a relatively monotonous, ~25.3m thick alluvial sedimentary sequence drilled in the Añavieja Basin (NE Spain). Results from the core AÑ2 suggest that the concentrationdependent magnetic parameters mainly reflect variations in the content of detrital magnetite, sourced in the catchment rocks and soils of the basin, via changes in the dynamics of alluvial fans due to temperature changes in the northern hemisphere during the Late Pleistocene. The correspondence between the magnetic proxies and the temperature variations in the North Atlantic region (NGRIP curve) indicates that higher (lower) concentrations and finer (coarser) magnetite grains coincide with warm (cold) periods. We propose that during cold periods, a sparser vegetation cover favored the incoming of higher energy runoff bearing coarser sediments to the basin that are relatively impoverished in magnetite. In contrast, during warm periods, the wider distribution of the vegetation cover associated with the lower runoff energy lead to finer, magnetite-richer sediment input to the basin. Maghemite, presumably of pedogenic origin, appears to be present also in the studied alluvial sediments. Further studies are necessary to unravel its palaeoclimatic significance

Gas-phase Elemental abundances in Molecular cloudS (GEMS) III. Unlocking the CS chemistry: the CS+O reaction

Context. Carbon monosulphide (CS) is among the most abundant gas-phase S-bearing molecules in cold dark molecular clouds. It is easily observable with several transitions in the millimeter wavelength range, and has been widely used as a tracer of the gas density in the interstellar medium in our Galaxy and external galaxies. However, chemical models fail to account for the observed CS abundances when assuming the cosmic value for the elemental abundance of sulfur. Aims. The CS+O → CO + S reaction has been proposed as a relevant CS destruction mechanism at low temperatures, and could explain the discrepancy between models and observations. Its reaction rate has been experimentally measured at temperatures of 150−400 K, but the extrapolation to lower temperatures is doubtful. Our goal is to calculate the CS+O reaction rate at temperatures <150 K which are prevailing in the interstellar medium. Methods. We performed ab initio calculations to obtain the three lowest potential energy surfaces (PES) of the CS+O system. These PESs are used to study the reaction dynamics, using several methods (classical, quantum, and semiclassical) to eventually calculate the CS + O thermal reaction rates. In order to check the accuracy of our calculations, we compare the results of our theoretical calculations for T ~ 150−400 K with those obtained in the laboratory. Results. Our detailed theoretical study on the CS+O reaction, which is in agreement with the experimental data obtained at 150–400 K, demonstrates the reliability of our approach. After a careful analysis at lower temperatures, we find that the rate constant at 10 K is negligible, below 10−15 cm3 s−1, which is consistent with the extrapolation of experimental data using the Arrhenius expression. Conclusions. We use the updated chemical network to model the sulfur chemistry in Taurus Molecular Cloud 1 (TMC 1) based on molecular abundances determined from Gas phase Elemental abundances in Molecular CloudS (GEMS) project observations. In our model, we take into account the expected decrease of the cosmic ray ionization rate, ζH2, along the cloud. The abundance of CS is still overestimated when assuming the cosmic value for the sulfur abundance

Ionic and electronic structure of sodium clusters up to N=59

We determined the ionic and electronic structure of sodium clusters with even electron numbers and 2 to 59 atoms in axially averaged and three-dimensional density functional calculations. A local, phenomenological pseudopotential that reproduces important bulk and atomic properties and facilitates structure calculations has been developed. Photoabsorption spectra have been calculated for $\mathrm{Na}_2$, $\mathrm{Na}_8$, and $\mathrm{Na}_9^+$ to $\mathrm{Na}_{59}^+$. The consistent inclusion of ionic structure considerably improves agreement with experiment. An icosahedral growth pattern is observed for $\mathrm{Na}_{19}^+$ to $\mathrm{Na}_{59}^+$. This finding is supported by photoabsorption data.Comment: To appear in Phys. Rev. B 62. Version with figures in better quality can be requested from the author

Derivation and external validation of the SIMPLICITY score as a simple immune-based risk score to predict infection in kidney transplant recipients

Existing approaches for infection risk stratification in kidney transplant recipients are suboptimal. Here, we aimed to develop and validate a weighted score integrating non-pathogen-specific immune parameters and clinical variables to predict the occurrence of post-transplant infectious complications. To this end, we retrospectively analyzed a single-center derivation cohort of 410 patients undergoing kidney transplantation in 2008-2013 in Madrid. Peripheral blood lymphocyte subpopulations, serum immunoglobulin and complement levels were measured at one-month post-transplant. The primary and secondary outcomes were overall and bacterial infection through month six. A point score was derived from a logistic regression model and prospectively applied on a validation cohort of 522 patients undergoing kidney transplantation at 16 centers throughout Spain in 2014-2015. The SIMPLICITY score consisted of the following variables measured at month one after transplantation: C3 level, CD4+ T-cell count, CD8+ T-cell count, IgG level, glomerular filtration rate, recipient age, and infection within the first month. The discrimination capacity in the derivation and validation cohorts was good for overall (areas under the receiver operating curve of 0.774 and 0.730) and bacterial infection (0.767 and 0.734, respectively). The cumulative incidence of overall infection significantly increased across risk categories in the derivation (low-risk 13.7%; intermediate-risk, 35.9%; high-risk 77.6%) and validation datasets (10.2%, 28.9% and 50.4%, respectively). Thus, the SIMPLICITY score, based on easily available immune parameters, allows for stratification of kidney transplant recipients at month one according to their expected risk of subsequent infection

Green function techniques in the treatment of quantum transport at the molecular scale

The theoretical investigation of charge (and spin) transport at nanometer length scales requires the use of advanced and powerful techniques able to deal with the dynamical properties of the relevant physical systems, to explicitly include out-of-equilibrium situations typical for electrical/heat transport as well as to take into account interaction effects in a systematic way. Equilibrium Green function techniques and their extension to non-equilibrium situations via the Keldysh formalism build one of the pillars of current state-of-the-art approaches to quantum transport which have been implemented in both model Hamiltonian formulations and first-principle methodologies. We offer a tutorial overview of the applications of Green functions to deal with some fundamental aspects of charge transport at the nanoscale, mainly focusing on applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references, submitted to Springer series "Lecture Notes in Physics