Hacia una teoría sobre las ideas científicas de los alumnos: influencia del contexto

The different constructive psychological theories present some difficulties in order to explain and justify the results obtained by the researches carried out within the field named pupils'conceptions. In this paper we introduce a new psycho-pedagogical model which agglutinates the main elements of the constructive theories. With that aim, the declarative knowledge is subdivided in several memories: episodic, scholastic semantic and experiential semantic. The procedural knowledge of reasoning in scholastic analysis and experiential analysis methods. We show some examples that are analyzed from our theoretic model. Later, we stress the relationship between pupils'answers and the context in which those are activated, showing the utility of the model here proposed

Concepciones de los alumnos sobre el enlace químico antes, durante y después de la enseñanza formal : problemas de aprendizaje

This paper describes the BUP and COU students' ideas (15-18 years old) about the continuity/discontinuity, atomic/ molecular conception, nature of the intramolecular and intermolecular bonds, as the notions of lattice and ion. The results show that the students' idea of continuity in gases declines when the students' academic level increase. The school succeeds in transmitting a molecular view of some substances. Nevertheless, students do not grasp the nature of the covalent bond. The molecular structure is more utilized than the lattice in the academic levels analyzed. The concept of ion and ionic lattice are not easily learned by the students. In this paper we point out some reasons that could explain these facts. Then we comment on some didactic implications that could help to overcome these obstacles

Jorge Juan: innovador de la Educación Superior en la España ilustrada

La Educación superior en la España de la Ilustración constituye una de las más claras manifestaciones de la renuncia de nuestro país a la aceptación de las corrientes renovadoras provenientes de Europa. Mientras la Universidad española seguía sin aceptar a Copérnico (1543), Jorge Juan introducía una verdadera revolución en la pedagogía científica con nuevos planes de enseñanza y novedosos libros de texto fundamentados en una actualización de Newton (1687) a la luz de los avances de la Matemática europea del siglo XVIII, desconocidos para el genio inglés. Con el rechazo de nuestras universidades, los esfuerzos reformadores de Jorge Juan sólo pudieron concretarse parcialmente en las Academias de la Armada, de modo que España permanece a mucha distancia con respecto a la Ciencia europea, desfase secular que sólo empezará a superarse en el siglo XX.Higher Education during Spanish Enlightenment constitutes one of the most clear examples of how our country resigned the acceptance of every current of renewal coming from Europe. While Spanish University continued rejecting Copernicus (1543), Jorge Juan introduced a complete revolution in Spanish scientific pedagogy through new teaching organization and textbooks full of novelties based upon an updating of Newton’s work (1687) through the advances in XVIII th century European Mathematics, still unknown to the English savant. Suffering the repulse from our universities Jorge Juan’s efforts towards reformation could only become effective at the Navy’sAcademies. Consequently Spain would remain at a secular distance from European Science, a gap that would only be overcome in XXth century

Concepciones de los alumnos de 15-18 años sobre la estructura interna de la material en el estado sólido

A questionary of free answers has been used in order to elicit pupils' ideas about the internal structure of some substances. The 15-16 years old pupils (2º de BUP) use an atomic framework with a gas and a non atomics one with solids. The differences between melting points are explained by pupils using macroscopic reasonings, atomic arguments, or mixting both of them

Effects of excitonic diffusion on stimulated emission in nanocrystalline ZnO

We present optically-pumped emission data for ZnO, showing that high excitation effects and stimulated emission / lasing are observed in nanocrystalline ZnO thin films at room temperature, although such effects are not seen in bulk material of better optical quality. A simple model of exciton density profiles is developed which explains our results and those of other authors. Inhibition of exciton diffusion in nanocrystalline samples compared to bulk significantly increases exciton densities in the former, leading, via the nonlinear dependence of emission in the exciton bands on the pump intensity, to large increases in emission and to stimulated emission

Infinitely long branches and an informal test of common ancestry

Background: The evidence for universal common ancestry (UCA) is vast and persuasive. A phylogenetic test has been proposed for quantifying its odds against independently originated sequences based on the comparison between one versus several trees. This test was successfully applied to a well-supported homologous sequence alignment, which was however criticized on the basis of simulations showing that alignments without any phylogenetic structure could mislead its conclusions.Results: Here we present a simplified version of this same counterexample, which can be interpreted as a tree with arbitrarily long branches, and where the UCA test fails again. We also present another case whereby any sufficiently similar alignment will favour UCA irrespective of the true independent origins for the sequences. Finally, we present a class of frequentist tests that perform better than the purportedly formal UCA test.Conclusion: Despite claims to the contrary, we show that the counterexamples successfully detected a drawback of the original UCA test, of relying on sequence similarity. In light of our own simulations, we therefore conclude that the UCA test as originally proposed should not be trusted unless convergence has already been ruled out a priori.Reviewers: This article was reviewed by Professor Eugene Koonin, Dr. Yuri I. Wolf and Professor William Martin

Exploraciones gráficas de ideas extraescolares de los alumnos sobre radiactividad

We present some aspects of radioactivity which somehow are familiar to the students, because as they pick information from outside the school, their leve1 of Knowledge of pupils is not as low as one might expect

SimPhy: Phylogenomic Simulation of Gene, Locus, and Species Trees

We present a fast and flexible software package--SimPhy--for the simulation of multiple gene families evolving under incomplete lineage sorting, gene duplication and loss, horizontal gene transfer--all three potentially leading to species tree/gene tree discordance--and gene conversion. SimPhy implements a hierarchical phylogenetic model in which the evolution of species, locus, and gene trees is governed by global and local parameters (e.g., genome-wide, species-specific, locus-specific), that can be fixed or be sampled from a priori statistical distributions. SimPhy also incorporates comprehensive models of substitution rate variation among lineages (uncorrelated relaxed clocks) and the capability of simulating partitioned nucleotide, codon, and protein multilocus sequence alignments under a plethora of substitution models using the program INDELible. We validate SimPhy's output using theoretical expectations and other programs, and show that it scales extremely well with complex models and/or large trees, being an order of magnitude faster than the most similar program (DLCoal-Sim). In addition, we demonstrate how SimPhy can be useful to understand interactions among different evolutionary processes, conducting a simulation study to characterize the systematic overestimation of the duplication time when using standard reconciliation methods. SimPhy is available at https://github.com/adamallo/SimPhy, where users can find the source code, precompiled executables, a detailed manual and example cases