Avanzando en la investigación sobre el conocimiento del profesor

La investigación sobre el conocimiento del profesor es una temática relevante en el campo de la Educación Matemática. Se pueden plantear muy diversas perspectivas teóricas para su caracterización (Ribeiro et al., 2014). Nuestra investigación, pretende dar un paso más en la línea de articular propuestas teóricas para una mejor comprensión del conocimiento del profesor y del aprendizaje o desarrollo profesional. Es una propuesta, por un lado prágmática, pretende profundizar en la caracterización del conocimiento del profesor, y por otro lado, indagar sobre las formas de articulación de teorías, en este caso haciendo una propuesta de tipo metodológica

Understanding chemical evolution in resolved galaxies -- I The local star fraction-metallicity relation

This work studies the relation between gas-phase oxygen abundance and stellar-to-gas fraction in nearby galaxies. We first derive the theoretical prediction, and argue that this relation is fundamental, in the sense that it must be verified regardless of the details of the gas accretion and star formation histories. Moreover, it should hold on "local" scales, i.e. in regions of the order of 1 kpc. These predictions are then compared with a set of spectroscopic observations, including both integrated and resolved data. Although the results depend somewhat on the adopted metallicity calibration, observed galaxies are consistent with the predicted relation, imposing tight constraints on the mass-loading factor of (enriched) galactic winds. The proposed parametrization of the star fraction-metallicity relation is able to describe the observed dependence of the oxygen abundance on gas mass at fixed stellar mass. However, the "local" mass-metallicity relation also depends on the relation between stellar and gas surface densities.Comment: 10 pages, 4 figures. Matches accepted version (significant typo corrected

ETo estandarizada en el sur de España ¿Cuál debe ser la referencia?

La evapotranspiración de referencia (ETo) cuantifica la demanda evaporativa del aire y es necesaria para el cálculo del uso consuntivo de agua de los cultivos. Las redes de estaciones agrometeorológicas proporcionan esta información, utilizando diferentes versiones de la ecuación de Penman-Monteith, realizando cálculos horarios o diarios. Este trabajo pretende arrojar luz sobre la controversia que existe en la utilización de ambos tiempos de cálculo, realizando una comparación a escala local y regional entre las versiones FAO56 y ASCE de esta ecuación. La comparación se realizó en 31 localizaciones de Andalucía, calculando los valores diarios mediante suma de horarios. Además, se comparó la estimación diaria de ETo de la ecuación FAO56-PM con la medida en un lisímetro de pesada en Córdoba. Los resultados de la comparación entre valores medidos y estimados usando ambas ecuaciones estandarizadas indican que los métodos más precisos para estimar los valores diarios de la ETo fueron FAO56-PM en base diaria y ASCE-PM en base horaria. Ambos mostraron una precisión similar cuando se compararon con los valores medidos en un lisímetro de pesada. La ecuación FAO56-PM en base horaria mostró una menor precisión, con subestimaciones del 5%. A escala regional, la ecuación FAO56-PM en base horaria subestimó los valores diarios de ETo calculados mediante la misma ecuación estandarizada en su versión ASCE hasta un 6%, produciéndose una subestimación media del 4%. Esta diferencia fue debida al uso de un mayor valor de rc (70 s m-1) en la ecuación FAO56-PM, en relación con el valor de 50 s m-1 aplicado en la ecuación estandarizada ASCE durante las horas diurnas.The most practical way to quantify water consumption by the crops is by using the concept of reference crop evapotranspiration (ETo). Agrometeorological networks provide daily ETo values using the Penman-Monteith equation on a daily or hourly basis. Up till now, the ETo methods are being used mainly for computation with a 24-h timestep because hourly meteorological data are not readily accessible for the users to apply ETo procedures on an hourly basis. This work quantifies the differences associated with using two different timesteps (hourly and daily basis) for computing ETo using two standardized Penman– Monteith equations (ASCE and FAO56) under different climatic conditions in Andalusia. Hourly ETo was measured in Córdoba, southern Spain, using a precision weighing lysimeter. Close to the lysimeter, an automatic weather station was located to register hourly meteorological variables. Penman-Monteith equation to estimate ETo was evaluated for hourly and daily estimates. ASCE and FAO-56 standardized ETo equations were also compared using data from 31 meteorological stations in Andalusia. Comparisons were made between daily ETo obtained by summing hourly standardized ASCE–Penman–Monteith estimations and calculated from the addition of hourly FAO56–Penman–Monteith estimations and daily ETo estimated on a daily basis. On an hourly basis, the FAO-56 version estimated lower than the ASCE version as 6% in some locations, with a difference of 4% on the average, mainly due to the higher surface resistance (70 s m−1) used in the FAO-56 version during daytime periods, as opposed to the 50 s m−1 value used by the ASCE version. The level of agreement improved when the two computational time steps (hourly and daily) were compared, because differences were lower (2% on the average)

Investigación sobre el concepto de grafo a través del modelo de Van Hiele

El presente trabajo tiene como objetivo indagar en la comprensión de los estudiantes universitarios sobre problemas de la Matemática discreta, en particular sobre la Teoría de Grafos (Biggs, 1994). Debido a las similitudes con la geometría por la fuerte componente visual de la teoría de grafos (más topológica que métrica), al menos en los primeros acercamientos a ella, hemos considerado como marco teórico para abordar esta investigación el modelo de Van Hiele adaptado a esta área de la Matemática

Bayesian estimation of the half-normal regression model with deterministic frontier

A regression model with deterministic frontier is considered. This type of model has hardly been studied, partly owing to the difficulty in the application of maximum likelihood estimation since this is a non-regular model. As an alternative, the Bayesian methodology is proposed and analysed. Through the Gibbs algorithm, the inference of the parameters of the model and of the individual efficiencies are relatively straightforward. The results of the simulations indicate that the utilized method performs reasonably wel

Sobre la capacidad de separar los dos errores en el modelo de frontera estocástica normal/half-normal

In this paper, a simulation experiment is carried out in the framework of the normal/half -normal stochastic frontier model in order to analyse its ability to disentangle the two types of errors that form the composite error. According to the results obtained through the mean bias and the mean squared error of the parameters and efficiencies, and via Spearman rank correlation between actual and estimated efficiencies, a good performance of the model is only obtained when considering medium -sized or large samples and the variance of the inefficiencies highly contributes to that of the composite error. The problems of wrong skewness and absence of random error are also addressed. The influence on the results of selecting a wrong distribution for the inefficienc y term is also analysedEn este artículo, se lleva a cabo un experimento de simulación en el contexto del modelo con frontera estocástica normal/half -normal para analizar su capacidad de separar los dos tipos de error que forman el error compuesto. Según los resultados obtenidos a través del sesgo medio y el error cuadrático medio de los parámetros y las eficiencias, y mediante el coeficiente de correlación por rangos de Spearman entre las eficiencias reales y las estimadas, se obtiene un buen comportamiento del modelo solo cuando se consideran muestras de tamaño me diano o grande y la varianza de las ineficiencias contribuye de forma muy importante a la del error compuesto. Los problemas de la asimetría errónea y de la ausencia de errores aleatorios también son abordados. La influencia en los resultados de selecciona r una distribución errónea para el término de ineficiencia también se analiz

Algunas observaciones acerca del uso de software en la estimación del modelo Half-Normal

Using the maximum likelihood method, in order to estimate Half-Normal stochastic frontier production models, entails several practical di±culties that, perhaps, have not been su±ciently emphasised. In employing FRONTIER software, we analyse the case in which the estimation obtained suggests the absence of random factors in the composite error term. We have proved that there are reasons to doubt the validity of the parameter estimates and especially of its standard errors. On the other hand, no estimation is obtained in the previous situation, with LIMDEP software, but an error message

A comparison between maximum likelihood and Bayesian estimation of stochastic frontier production models

In this paper, the finite sample properties of the maximum likelihood and Bayesian estimators of the half-normal stochastic frontier production function are analyzed and compared through a Monte Carlo study. The results show that the Bayesian estimator should be used in preference to the maximum likelihood owing to the fact that the mean square error performance is substantially better in the Bayesian framewor

Flipped classroom evaluation using kahott and moodle in the undergraduate teaching lab

Comunicación presentada en EDULEARN 2018, 10th International Conference on Education and New Learning Technologies (July 2-4, 2018, Palma, Mallorca, Spain).This article analyzes the implementation of a flipped classroom methodology in the undergraduate teaching labs of engineering degrees. The methodology is focused on providing the students, before the lab session, with audio-visual resources that cover the theoretical background and explanations needed to follow the session. At the beginning of each lab session, the preparatory work performed by the students is evaluated with an on-line test, which was performed using Kahoot and Moodle resources and has an impact on the mark of the session. This methodology is helpful in the sense that eliminates the frequently required theoretical introduction, allowing devoting more time to the experimental part. On the other hand, it provides an immediate information of the degree of prior knowledge gained by the students, so the weaker aspects can be reinforced during the lab session. An analysis of the advantages and disadvantages found for the two on-line resources employed, in conjunction with the impact produced on the students by the methodology is presented. Moodle was found to show greater seriousness and more versatility to introduce the test questions. However, the use of Kahoot was preferred by the students, since it creates a more relaxed lab atmosphere, which was also very useful to increase the participation of some students who were unmotivated. The students recognized that the methodology helped to better follow the lab sessions and improved the quality of their lab reports, which are the items used for their evaluation