Revisión sistemática de la producción española sobre rendimiento académico entre 1980 y 2011

El bajo rendimiento académico sigue siendo un problema de investigación de gran impacto social. Sin embargo, los resultados científicos no están teniendo repercusión en la mejora, ni en las políticas educativas. En este trabajo nos propusimos identificar, ordenar, analizar y extraer conclusiones sobre la producción española sobre rendimiento académico, con el fin de visualizarla y derivar problemas futuros objeto de investigación. Para ello se llevó a cabo un estudio de revisión en seis etapas, en el que se combinaron procedimientos metodológicos de investigación de síntesis y de investigación bibliométrica. Se identificaron las publicaciones en cuatro bases de datos españolas; posteriormente se analizaron y codificaron los datos extraídos alrededor de nueve indicadores: título, año, tipo de documento, editorial, autor, número autores, institución, comunidad autónoma y tema. Los resultados muestran una producción constante y creciente (1595 referencias), pero dispersa, tanto por el inmenso número de autores que publican, la mayoría con un solo trabajo, como por los lugares donde publican. Las temáticas más tratadas se refieren en primer lugar a modelos explicativos, diagnóstico y tratamiento; en segundo lugar se abordan los factores y variables determinantes del bajo y alto rendimiento académico; en tercer lugar se desarrollan estudios sobre legislación y de otras variables psicológicas y educativas en relación con el rendimiento. Este estudio supone una aproximación sintetizada de la producción sobre rendimiento académico en España, y un primer paso para investigaciones de síntesis posteriores, que nos permitan identificar buenas prácticas para el ejercicio de “prácticas basadas en la evidencia”, y otros problemas de investigación.

Electrochemical synthesis and characterization of conducting polymers using room temperature melt as an electrolyte

Aromatic monomers can be polymerised using the chloroaluminate room temperature melt obtained by mixing 1:2 ratio of cetyl pyridinium chloride and anhydrous aluminium chloride miscible in all proportions with organic solvents as an electrolyte. The chloroaluminate (AlCl4-) anion generated in this melt having a tetrahedral symmetry with equal bond lengths and bond angles is the dopant to stabilize macrocation generated near the vicinity of anode to yield better conducting and better ordered electronically conducting free standing polymer film. In this communication, we discuss the polymers derived from benzene and pyrrole and their characterization by various techniques.

Fractal rotation isolates mechanisms for form-dependent motion in human vision

Here, we describe a motion stimulus in which the quality of rotation is fractal. This makes its motion unavailable to the translationbased motion analysis known to underlie much of our motion perception. In contrast, normal rotation can be extracted through the aggregation of the outputs of translational mechanisms. Neural adaptation of these translation-based motion mechanisms is thought to drive the motion after-effect, a phenomenon in which prolonged viewing of motion in one direction leads to a percept of motion in the opposite direction. We measured the motion after-effects induced in static and moving stimuli by fractal rotation. The after-effects found were an order of magnitude smaller than those elicited by normal rotation. Our findings suggest that the analysis of fractal rotation involves different neural processes than those for standard translational motion. Given that the percept of motion elicited by fractal rotation is a clear example of motion derived from form analysis, we propose that the extraction of fractal rotation may reflect the operation of a general mechanism for inferring motion from changes in form.

Differences in composition of macroinvertebrate communities with invasive and native Gammarus spp. (Crustacea : Amphipoda)

1. Assessing the effects on communities of invasive species is often confounded by environmental factors. In Irish rivers, the introduced amphipod Gammarus pulex replaces the native G. duebeni celticus in lowland stretches. The two amphipods are associated with different macroinvertebrate communities, which may in part be the result of natural longitudinal physicochemical change. However, this hinders assessment of any direct community impacts of the invasive as compared with the native species. Here, we report on a fortuitous circumstance that allowed us to uncouple the community effects of Gammarus species from environmental differences.

Observations towards early-type stars in the ESO-POP Survey - II. Searches for intermediate- and high-velocity clouds

We present Ca it K and Ti it optical spectra of early-type stars taken mainly from the ultraviolet and visual echelle spectrograph (LIVES) Paranal Observatory Project, plus H 1 21-cm spectra, from the Vila-Elisa and Leiden-Dwingeloo Surveys, which are employed to obtain distances to intermediate- and high-velocity clouds (IHVCs). H I emission at a velocity of -117 km s(-1) towards the sightline HD 30677 (l, b = 190 degrees.2, -22 degrees.2) with column density -1.7 x 10(19) cm(-2) has no corresponding Ca Pi K absorption in the LIVES spectrum, which has a signal-to-noise ratio (S/N) of 610 per resolution element. The star has a spectroscopically determined distance of 2.7 kpc, and hence sets this as a firm lower distance limit towards Anti-Centre cloud ACII. Towards another sightline (HD 46185 with 1, b = 222 0, -10 degrees.1), H1 at a velocity of +122 km s(-1) and column density of 1.2 x 10(19) cm(-2) is seen. The corresponding Ca Pi K spectrum has a S/N of 780, although no absorption is observed at the cloud velocity. This similarly places a firm lower distance limit of 2.9 kpc towards this parcel of gas that may be an intermediate-velocity (IV) cloud. The lack of IV Ca it absorption towards HD 196426 (1, b = 45 degrees.8, -23 degrees.3) at a S/N of 500 reinforces a lower distance limit of -700 pc towards this part of complex gp, where the H I column density is 1.1 x 1019 cm(-2) and velocity is +78 km s(-1). Additionally, no IV Cart is seen in absorption in the spectrum of HD 19445, which is strong in H I with a column density of 8 x 10(19) cm(-2) at a velocity of - -42 km s(-1), placing a firm although uninteresting lower distance limit of 39 pc to this part of IV South. Finally, no high-velocity Call K absorption is seen towards HD 115363 (l, b = 306.0,-1.0) at a S/N of 410, placing a lower distance of -3.2 kpc towards the HVC gas at velocity of - +224 km s(-1) and WE column density of 5.2 x 10(19) cm(-2). This gas is in the same region of the sky as complex WE (Wakker 2001), but at higher velocities. The non-detection of Ca it K absorption sets a lower distance of -3.2 kpc towards the HVC, which is unsurprising if this feature is indeed related to the Magellanic System.

Application of NMR based metabolomics for mapping metabolite variation in European wheat

In this study, we report on the use of NMR-based metabolomics to access variation in low molecular weight polar metabolites between the European wheat cultivars Apache, Charger, Claire and Orvantis. Previous unassigned resonances in the published NMR spectra of wheat extracts were identified using C NMR and two dimensional proton-carbon NMR. These included a peak for trans-aconitate (d3.43) and resonances corresponding to fructose in the crowded carbohydrate region of the spectra. Large metabolite differences were observed between two different growth stages, namely the coleoptile and two week old leaf tissue extracts which were consistent across cultivars. Two week old leaf tissue extracts had higher abundances of glutamine, glutamate, sucrose and trans-aconitate and less glucose and fructose than were observed in the coleoptile extracts. Across both growth stages the cultivars Apache and Charger showed the greatest differences in metabolite profiles. Charger had higher abundances of betaine, the single most influential metabolite in the principal component analysis, in addition to fructose and sucrose. However, Charger had lower levels of aspartate, choline and glucose than Apache. These findings demonstrate the potential for a biochemical mapping approach using NMR, across European wheat germplasm, for metabolites of known importance to functional characteristics. © Springer Science+Business Media, LLC 2009.

Lanthanide-doped luminescent ionogels

Ionogels are solid oxide host networks con. ning at a meso-scale ionic liquids, and retaining their liquid nature. Ionogels were obtained by dissolving lanthanide(III) complexes in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [C(6)mim][Tf2N], followed by confinement of the lanthanide-doped ionic liquid mixtures in the pores of a nano-porous silica network. [C(6)mim][Ln(tta)(4)], where tta is 2-thenoyltrifluoroacetonate and Ln = Nd, Sm, Eu, Ho, Er, Yb, and [choline](3)[Tb(dpa)(3)], where dpa = pyridine-2,6-dicarboxylate (dipicolinate), were chosen as the lanthanide complexes. The ionogels are luminescent, ion-conductive inorganic-organic hybrid materials. Depending on the lanthanide(III) ion, emission in the visible or the near-infrared regions of the electromagnetic spectrum was observed. The work presented herein highlights that the confinement did not disturb the first coordination sphere of the lanthanide ions and also showed the excellent luminescence performance of the lanthanide tetrakis beta-diketonate complexes. The crystal structures of the complexes [C(6)mim][Yb(tta)(4)] and [choline](3)[Tb(dpa)(3)] are reported.

La amistad cívica en Aristóteles: concordia y fraternidad

El artículo muestra la importancia de la amistad en el contexto de la filosofía política aristotélica. Esta importancia se verifica en su peso específico en comparación con la justicia, puesto que Aristóteles mismo sostiene que la amistad cívica es incluso un objetivo superior al de la búsqueda de la justicia. En concreto, el artículo se centra en la función de la concordia, como tipo especial de amistad cívica, en términos de conservación de la unidad y estabilidad de la polis. Para captar su significación, se plantea el papel de la concordia como complemento a la condición política del ser humano. La concordia es necesaria a la luz de la tendencia a la lucha entre las partes de la ciudad, entre el demos y los oligarcas. Puesto que esta lucha pone en peligro la continuidad de la polis, la concordia entre ciudadanos se convierte en un antecedente privilegiado del principio de fraternidad republicana, el cual todavía no ha gozado de una atención suficiente en el campo de la historia de la filosofía política.

El "Fedro" de Platón: un ejercicio de buena retórica engañosa

En este artículo me propongo mostrar que lo que Sócrates hace con Fedro a lo largo de toda la obra no es otra cosa que utilizar la auténtica retórica (con su doble carga, dialéctica y psicológica) que es descrita en la segunda parte del diálogo. Las tensiones, rivalidades y celos de la situación inicial entre ellos expone un perfil representativo de relaciones entre interlocutores con perspectivas intelectuales opuestas. Es preciso disolver la resistencia emocional por medio de una serie de pasos graduales, estratégicos, y ‘engañosos’ (no se puede develar el propio juego desde el principio). Hay que partir de acuerdos, siquiera parciales, para continuar dialogando. Sin embargo, Sócrates también introduce nociones nuevas acerca del amor, pero éstas pasan desapercibidas a un Fedro obsesionado con la imitación de su enamorado Lisias. Hasta que Sócrates decide cortar el juego y cruzar el río. Este corte provoca un giro en ambos personajes: Fedro se dispone a escuchar lo que Sócrates quiere contarle (el mito del carro alado) y Sócrates se revela ante sí mismo como un personaje capaz de ‘encantar’ a Fedro con la belleza rapsódica del relato y superar su propio temor de convertirse en una bestia devoradora. Al final Sócrates muestra su juego a Fedro y le enseña cómo ha sido posible llegar a un auténtico diálogo filosófico, donde pueda tener lugar la enseñanza y el aprendizaje recíprocos.