Influencia de los modelos intuitivos en la comprensión de la multiplicación y la división

Since the stdy by Fischbein et al. (1985) which suggested that children develop intuitive models about multiplication and division early, much research has offered data that corroborate these models. In this study we analyze the differential weight of the models in three kid of task: algorithms, problem solving, and problem posing. We included two age groups (1st of ESO and 8th of EGB), and three kid of quantities (whole numbers, decimals and fractions). The results indicated that the intuitive models did not have the same differential weight for the different tasks. For instance, the problem posing task did not seem suited to the conditions under which the intuitive models act. Likewise, the presence of quantities that failed to observe one or more restrictions of the models did not have a negative influence. In contrast, the errors committed in the two remaining tasks were almost exclusively due to the application of the intuitive rules.A partir del trabajo de Fischbein et al. (1985) que sugiere que los niños construyen tempranamente modelos intuitivos sobre la multiplicación y división, numerosas investigaciones han ofrecido datos consistentes con estos modelos. En este estudio analizamos el peso diferencial de los modelos en tres tipos de tareas: resolver algoritmes, resolver problemas y plantear problemas. Hemos incluido también dos grupos de edad (1º de ESO y 8º de EGB), asi como tres tipos de cantidades (enteros, decimales y fracciones). LoS resultados indicaron que los modelos intuitivos no tuvieron el mismo peso diferencial en las diferentes tareas. Por ejemplo, la tarea de plantear problemas no parecía reunir las condiciones bajo las que actúan los modelos intuitivos. Asimismo, la presencia de cantidades que alteraban una o más imposiciones de los modelos no influyó negativamente. Por el contrario, los errores de las dos tareas restantes se debieron a la aplicación de las reglas intuitivas

Piezochromic properties of pyridil divinyl anthracene derivatives: a joint Raman and DFT study

Piezochromic materials, which show color changes resulting from external pressure or mechanical grinding, are of great interest from a scientific viewpoint owing to their potential applications as pressure-sensing and optical-recording systems.[1] It has been recently discovered solid-state fluorescence properties and piezochromic luminescence in a family of 9,10-Bis((E)-n-(pyrid-2-yl)vinyl)anthracene, BPnVA (n=2 orto-,3 metha- and 4 para-) compounds, see Figure 1.[2] The crystal structures indicate that the three compounds with varying position of the nitrogen on the external pyridyl exhibit different molecular packing modes. In this work, we aim at providing further insight into the interplay played by the molecular and supramolecular structural changes and the luminescence changes observed under pressure by using a combined experimental-theoretical approach that links Raman spectroscopy with DFT calculations.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Limited medial osteochondral lesions of the talus associated with chronic ankle instability do not impact the results of endoscopic modified Broström ligament repair

Background The arthroscopic modified Brostrom procedure, with repair of the anterior talofibular ligament and extensor retinaculum, produces good functional outcomes in patients with chronic lateral ankle instability (CLAI). CLAI can be associated with osteochondral lesions of the talus (OLTs). It remains unclear whether associated limited OLTs affect clinical outcomes in such patients. Methods This retrospective cohort study included 92 CLAI patients with and without OLTs undergoing an all-inside arthroscopic modified Brostrom procedure from June 2016 to May 2019. The patients were divided into non-lesion group (n = 32) and lesion group (n = 60) according to whether CLAI was associated or not with OLTs. All the osteochondral lesions less than 15 mm in diameter were managed with bone marrow stimulation techniques (arthroscopic microfracture) at the time of the arthroscopic modified Brostrom procedure. The Visual Analogue Scale (VAS) scores, American Orthopedic Foot and Ankle Society (AOFAS) scores, Karlsson Ankle Function Score (KAFS), Anterior Talar Translation (ATT), Active Joint Position Sense (AJPS), and the rate of return to sports were compared in both groups. Results Increase in all the functional scores (VAS, AOFAS, KAFS, ATT, and AJPS) in both groups was, respectively, recorded 1 year and 2 years after surgery. At the 1-year and 2-year follow-up, there was no significant difference in the VAS, AOFAS, KAFS, ATT, and AJPS scores between the non-lesion and lesion groups. Conclusion In patients with CLAI who underwent an arthroscopic modified Brostrom procedure, the presence of limited OLTs (less than 15 mm in diameter), which required arthroscopic microfracture, did not exert any influence on outcome

An improved optimization technique for estimation of solar photovoltaic parameters

The nonlinear current vs voltage (I-V) characteristics of solar PV make its modelling difficult. Optimization techniques are the best tool for identifying the parameters of nonlinear models. Even though, there are different optimization techniques used for parameter estimation of solar PV, still the best optimized results are not achieved to date. In this paper, Wind Driven Optimization (WDO) technique is proposed as the new method for identifying the parameters of solar PV. The accuracy and convergence time of the proposed method is compared with results of Pattern Search (PS), Genetic Algorithm (GA), and Simulated Annealing (SA) for single diode and double diode models of solar PV. Furthermore, for performance validation, the parameters obtained through WDO are compared with hybrid Bee Pollinator Flower Pollination Algorithm (BPFPA), Flower Pollination Algorithm (FPA), Generalized Oppositional Teaching Learning Based Optimization (GOTLBO), Artificial Bee Swarm Optimization (ABSO), and Harmony Search (HS). The obtained results clearly reveal that WDO algorithm can provide accurate optimized values with less number of iterations at different environmental conditions. Therefore, the WDO can be recommended as the best optimization algorithm for parameter estimation of solar PV