Un modelo alternativo al algoritmo vertical de la multiplicación : el algoritmo de red.

La autora, tras revisar las teorías sobre la adquisición de la multiplicación, el proceso de construcción de las relaciones multiplicativas, y partiendo de una experiencia con niños sobre la utilización del algoritmo tipo red (S. XV) para un mejor aprendizaje de la multiplicación aritmética, inicia su investigación partiendo de la hipótesis de que este método basado en el producto cartesiano, se ajusta mejor a las estructuras del pensamiento, y por tanto, permite una mejor comprensión también en sujetos adultos. Compuesta por 17 sujetos entre 26 y 52 años, 16 mujeres y 1 hombre, pertenecientes a Educación Permanente de Adultos de Elda (Alicante), aunque la investigación sólo la finalizaron 4 sujetos por muerte experimental del 76'5 por ciento. La investigación utiliza un diseño de pretest-postest. Pruebas 'ad hoc' utilizadas en el pretest-postest que consistían en una serie de ítems que, independientemente dan información sobre los distintos aspectos de la multiplicación. Programa escolar utilizado para la enseñanza de la multiplicación. Resolución de problemas reales, cotidianos, de los sujetos por medio de la operación de multiplicar. Análisis cualitativo de los datos comparados en el pretest y el postest, enumeración de los progresos y/o estancamientos de los sujetos de la investigación. El método del algoritmo en red sí permite la capacitación de los individuos pues posibilita la construcción de estructuras multiplicativas. Desde el punto de vista empírico esto es válido, aunque, en los sujetos de esta investigación, debido a sus especiales características no ha podido ser discriminativo para la comprobación de la hipótesis. Aunque el algoritmo empleado ha favorecido la comprensión de la multiplicación, no ha motivado suficientemente a los sujetos por diversos motivos: A) No se ajusta a sus intereses que son el aprendizaje de las tablas de multiplicar. B) Confunden rapidez con efectividad. C) No tiene relación con las nociones anteriores sobre el tema. D) Siguen anclados en estructuras aditivas por lo que no encuentran significado a otra entidad matemática.

Blended learning (formaci??n semi-presencial) en educaci??n f??sica

Se describe una actividad llevada a cabo en el IES Bembezar (Azuaga, Badajoz) cuyo objetivo era el desarrollo de contenidos te??rico pr??cticos del bloque de condici??n f??sica y salud a trav??s de un modelo de blended-learning.

Conflictos semi??ticos sobre la correlaci??n y regresi??n en los libros de texto de bachillerato

Resumen basado en el de la publicaci??n

Explorando el uso de estrategias discursivas y semi??ticas en la construcci??n guiada del conocimiento

Resumen basado en el de la publicaci??n

Evaluación de la competencia comunicativa académica en semi-presencialidad

En la E.U. de Magisterio de Donostia de la Universidad del País Vasco (UPV/EHU), este curso 2010/2011 ha comenzado la oferta semi-presencial para aquellos estudiantes que no pueden matricularse a todas las asignaturas de primer curso. Dentro de esta experiencia piloto se ha impartido la asignatura "Desarrollo de la competencia comunicativa I" en el Grado de Educación Primaria, centrada en la competencia comunicativa académica. El diseño de esta asignatura se ha apoyado en investigaciones relacionadas con el desarrollo de esta competencia en entornos virtuales y ha contado con actividades diversas que han permitido a los estudiantes su autoevaluación y también la coevaluación

The diabatic contour advective semi-Lagrangian model

This article describes a novel algorithmic development extending the contour advective semi-Lagrangian model to include nonconservative effects. The Lagrangian contour representation of finescale tracer fields, such as potential vorticity, allows for conservative, nondiffusive treatment of sharp gradients allowing very high numerical Reynolds numbers. It has been widely employed in accurate geostrophic turbulence and tracer advection simulations. In the present, diabatic version of the model the constraint of conservative dynamics is overcome by including a parallel Eulerian field that absorbs the nonconservative ( diabatic) tendencies. The diabatic buildup in this Eulerian field is limited through regular, controlled transfers of this field to the contour representation. This transfer is done with a fast newly developed contouring algorithm. This model has been implemented for several idealized geometries. In this paper a single-layer doubly periodic geometry is used to demonstrate the validity of the model. The present model converges faster than the analogous semi-Lagrangian models at increased resolutions. At the same nominal spatial resolution the new model is 40 times faster than the analogous semi-Lagrangian model. Results of an orographically forced idealized storm track show nontrivial dependency of storm-track statistics on resolution and on the numerical model employed. If this result is more generally applicable, this may have important consequences for future high-resolution climate modeling.

The timing of Quaternary calcrete development in semi-arid southeast Spain: Investigating the role of climate on calcrete genesis

Quaternary-aged calcrete horizons are common weathering products in arid and semi-arid regions. It is, however, unclear how calcrete forming processes respond to the major oscillations in climate that occur over the Quaternary period. This paper presents a U-series-based calcrete age database from the Sorbas basin, southeast Spain. The study constructs an age frequency distribution of these ages which is consequently compared to a range of palaeoenvironmental records from the Mediterranean. The age distribution presented here suggests that the formation of pedogenic calcrete horizons in the Sorbas basin primarily occurs during 'warm' isotope stages (MIS 1 and 5), with very few calcrete ages occurring during cold glacial/stadial stages (MIS 2, 3 and 4). It is suggested that this is a function of the environments that existed during 'warm' isotope stages being more conducive to calcrete development than those that existed during cold climate episodes. In a semi-arid region such as the Sorbas basin it is likely that increased aridity during glacial stages, coupled with reduced vegetation and accelerated landscape instability, was crucial in reducing rates of calcrete formation. In a semi-arid region such as southeast Spain, calcrete formation during the Quaternary, therefore, oscillates with climate change but is primarily a "warm" episode phenomenon. It is suggested that further studies are required to see how calcrete genesis responds to environmental change in more humid parts of the Mediterranean. (C) 2009 Elsevier B.V. All rights reserved.

A semi-quantitative approach to deriving a model structure for the uptake of organic chemicals by vegetation

An expert elicitation exercise was undertaken to determine those components and processes that are most important for modeling plant uptake of organic chemicals. The state of our knowledge of these processes was also assessed. This semi-quantitative analysis allowed the construction of an idealized model with seven compartments; soil bulk, soil water, roots, stem, leaves, fruit, and air. Three main areas were identified further research: 1) the uptake of organic chemicals by fruit; 2) the internal transfer of organic chemicals between plant structures (e.g., stem and leaves); and 3) the transfer via the soil-air-plant pathway. Until new data becomes available to quantify these processes, it is proposed that an equilibrium partitioning approach is used between plant components other than fruit or that models consist of both an edible and inedible compartment.

Effects of manure and fertilizer on grain yield, soil carbon and phosphorus in a 13-year field trial in semi-arid Kenya

Long-term indicators of soil fertility were assessed by measuring grain yield, soil organic carbon (SOC) and soil Olsen phosphorous for a P-deficient soil. In one set of treatments, goat manure was applied annually for 13 years at 0, 5 and 10 t ha(-1), and intercrops of sorghum/cowpea, millet/green gram and maize/pigeonpea were grown. Yield depended on rainfall and trends with time were not identifiable. Manure caused an upward trend in SOC, but 10 t ha(-1) manure did not give significantly more SOC than 5 t ha(-1). Only 10 t ha(-1) manure increased Olsen P. Measurements of both SOC and Olsen P are recommended. In another set of treatments, manure was applied for four years; the residual effect lasted another seven to eight years when assessed by yield, SOC and Olsen P Treatment with mineral fertilizers provided the same rates of N and P as 5 t hat manure and yields from manure and fertilizer were similar. Fertilizer increased Olsen P but not SOC. Management systems with occasional manure application and intermediate fertilizer applications should be assessed. Inputs and offtakes of C, N and P were measured for three years. Approximately 16, 25 and 11% of C, N and P respectively were stabilized into soil organic matter from 5 t ha(-1) a(-1) manure. The majority of organic P was fixed as soil inorganic P.

Effect of manure application on crop yield and soil chemical properties in a long-term field trial of semi-arid Kenya

The sustainability of cereal/legume intercropping was assessed by monitoring trends in grain yield, soil organic C (SOC) and soil extractable P (Olsen method) measured over 13 years at a long-term field trial on a P-deficient soil in semi-arid Kenya. Goat manure was applied annually for 13 years at 0, 5 and 10 t ha(-1) and trends in grain yield were not identifiable because of season-to-season variations. SOC and Olsen P increased for the first seven years of manure application and then remained constant. The residual effect of manure applied for four years only lasted another seven to eight years when assessed by yield, SOC and Olsen P. Mineral fertilizers provided the same annual rates of N and P as in 5 t ha(-1) manure and initially ,gave the same yield as manure, declining after nine years to about 80%. Therefore, manure applications could be made intermittently and nutrient requirements topped-up with fertilizers. Grain yields for sorghum with continuous manure were described well by correlations with rainfall and manure input only, if data were excluded for seasons with over 500 mm rainfall. A comprehensive simulation model should correctly describe crop losses caused by excess water.