Problemas de terminología en estudios realizados acerca de "lo que el alumno sabe" sobre ciencias

In this paper we have carried out a bibliographic review of the terms currently used by science education researchers to describe «pupils' knowledge» of Science. Further, we have analised their meanings from the perspective of the methodological framework used and have offered our own proposal, as a result of that review, so as to reach a consensus on both the terminology and the possible range of meanings to bt: used. It must be pointed out that we have excluded those studies which discuss "pupils' knowledge" from a purely psychological perspective because of the enormous amount of bibliography on this topic

Effects of Non-Circular Motions on Azimuthal Color Gradients

Assuming that density waves trigger star formation, and that young stars preserve the velocity components of the molecular gas where they are born, we analyze the effects that non-circular gas orbits have on color gradients across spiral arms. We try two approaches, one involving semi-analytical solutions for spiral shocks, and another with magnetohydrodynamic (MHD) numerical simulation data. We find that, if non-circular motions are ignored, the comparison between observed color gradients and stellar population synthesis models would in principle yield pattern speed values that are systematically too high for regions inside corotation, with the difference between the real and the measured pattern speeds increasing with decreasing radius. On the other hand, image processing and pixel averaging result in systematically lower measured spiral pattern speed values, regardless of the kinematics of stellar orbits. The net effect is that roughly the correct pattern speeds are recovered, although the trend of higher measured $\Omega_p$ at lower radii (as expected when non-circular motions exist but are neglected) should still be observed. We examine the Martinez-Garcia et al. (2009) photometric data and confirm that this is indeed the case. The comparison of the size of the systematic pattern speed offset in the data with the predictions of the semi-analytical and MHD models corroborates that spirals are more likely to end at Outer Lindblad Resonance, as these authors had already found.Comment: 32 pages, 15 figures, accepted to Ap

Clinical management of homocystinuria; case report and review of the literature

La homocistinuria es un error congénito del metabolismo de la metionina que conduce al acúmulo de metionina y de su principal metabolito, homocisteína, en plasma, orina y tejidos. El acúmulo de homocisteína posee toxicidad sobre los sistemas óseo (osteoporosis), ocular (luxación del cristalino), nervioso (convulsiones, alteraciones psiquiátricas) y vascular (accidentes cerebrovasculares, enfermedad cardiovascular). Presentamos 2 casos de homocistinuria en 2 pacientes hermanos y, a continuación, revisamos las estrategias terapéuticas disponiblesHomocystinuria is a congenital disorder of methyonine metabolism that leads to increased plasmatic, urinary and tissue deposits of methyonine and its main metabolite: homocysteine. Homocysteine deposits are toxic for the skeletal system (osteoporosis), the eyes (lens dislocation), central nervous system (seizures, psychiatric disorders) and also induce vascular damage (stroke and other cardiovascular events). This article reports two patients with homocystinuria in two siblings, followed by a concise review on the therapeutic strategies available for this disorde

Construction of a high anchored wall at highway EX-A1 (Spain)

Descripción de la problemática encontrada en un desmonte de la autovía EX-A1 (Navalmoral de la Mata-Frontera portuguesa). Descripción de la solución adoptada: muro anclado. Highway EX-A1, near the Spain-Portugal border, crosses a Tertiary formation of weak marly rocks that are affected by high tectonic stresses that had created a good number of failure planes within the rock. During the past geologic times, some large landslides had taken place. They are now covered by Quaternary soils. The design of high cuts in this type of rock formation is somewhat troublesome. The paper indicates one of the solutions that have been implemented to stabilize one of the main highway cuts. L’autoroute EX-A1, près de la frontière entre l’Espagne et le Portugal, traverse une formation tertiaire de roches marneuses faibles avec des contraintes tectoniques élevées qui ont provoqué de nombreuses surfaces de rupture dans la roche. Au cours des temps géologiques passés, des grands glissements ont eu lieu et ils se retrouvent maintenant couverts par des sols quaternaires. Le projet d’excavations de grande hauteur dans cette formation rocheuse est généralement problématique. L’article décrit la solution qui a été mise en oeuvre pour stabiliser un des principaux déblais de l’autoroute

Methodology to quantify clogging coefficients for grated inlets. Application to SANT MARTI catchment (Barcelona)

Within the drainage system of a city, the set of inlets is in charge of taking the runoff produced by local storms to the stormwater/sewer. In the drainage system design the selection of appropriate inlet models and their location is one of the fundamental aspects. The hydraulics of these inlets has received great attention within the last years; however, few inlet makers provide the hydraulic capacity of their products. In addition, these data usually consider clean water, while in reality, numerous inlets can be either totally or partially clogged. This aspect should be kept in mind within the design process. In this paper, a methodology to consider the hydraulic effects of clogging phenomena is presented. The work started from a visual inspection of the grated inlets throughout the urban catchment of Sant Martí, Barcelona, as a means of identifying clogging patterns, their repetitive forms and their associated frequency. After that, clogged patterns were reproduced in laboratory testing of typical inlets types, thereby obtaining the real quantity of water that could be captured by each of them. It was shown that the same expression employed to describe the efficiency of clean inlets can be used to assess the efficiency of those clogged. A reduction factor in terms of hydraulic capacity and related to each clogging pattern has been defined for use in hydraulic studies of runoff along streets. Finally, the paper compares the obtained results in terms of clogging coefficient with another experimental campaign carried out in other catchment of the city

Temporal and spatial variations of atmospheric radiocarbon in the Mexico City metropolitan area

This work is licensed under a Creative Commons Attribution 3.0 License.-- et al.Proceedings of the 1st International Radiocarbon in the Environment Conference 18–22 August 2014, Queen’s University Belfast, Belfast, Northern Ireland (UK).The Mexico City Metropolitan Area (MCMA) produces a complex mixture of gases and aerosols from diverse sources, including burning of fossil fuels, biomass, and wastes, with a significant biogenic contribution. We present the first results of ongoing projects to study temporal and spatial variations of 14CO2 in the area. Temporal variations reconstructed from tree rings of Taxodium mucronatum indicate a considerable radiocarbon depletion, in accordance to the vast amount of fossil fuels burnt inside Mexico Valley, with values between 62 and 246‰ lower than background values for the 1962–1968 period, and lower by 51–88‰ for the 1983–2010 period. The lower dilution found for the last decades might indicate an increase in enriched 14CO2 sources. Results from the spatial distribution, as revealed from integrated CO2 samples and grasses from six points within the MCMA collected during the 2013 dry season, show variations between sites and sample types. For integrated CO2 samples, values range from 35.6‰ to 54.0‰, and for grasses between –86.8‰ and 40.7‰. For three of the sampling points, the grasses are significantly depleted, by up to ~133‰, as compared to the corresponding integrated CO2 sample. This may result from differences in the carbon assimilation period and exposure to different CO2 sources. Higher-than-background Δ14C values were found for all integrated CO2 samples, presumably resulting from 14C-enriched CO2 derived from forest fires in the mountains during the sampling period. Results obtained so far confirm the complexity of the 14C cycle in the MCMA.This research is funded by DGAPA-UNAM through project PAPIIT-IN106113. Scholarships from CONACyT for AMJ and AMR and from Instituto de Geología and DGAPA-UNAM for AGS are gratefully acknowledged.Peer Reviewe

A note on the likelihood and moments of the skew-normal distribution

In this paper an alternative approach to the one in Henze (1986) is proposed for deriving the odd moments of the skew-normal distribution considered in Azzalini (1985). The approach is based on a Pascal type triangle, which seems to greatly simplify moments computation. Moreover, it is shown that the likelihood equation for estimating the asymmetry parameter in such model is generated as orthogonal functions to the sample vector. As a consequence, conditions for a unique solution of the likelihood equation are established, which seem to hold in more general setting.Peer Reviewe

LA INVERSIÓN EN ACTIVOS FIJOS REALES PRODUCTIVOS: INCENTIVOS Y OBSTÁCULOS TRIBUTARIOS

RESUMENLas inversiones empresariales dirigidasa mejorar los procesos y a reducircostos, en ciertos casos, suscitan dificultadesde interpretación contablefrente a la jurídica impositiva. Estecaso describe la situación que afrontóSugar S.A. al utilizar la deducción tributariaespecial del 40% del valor desus inversiones efectivas realizadas,para disminuir la base de liquidacióny a su vez su impuesto de renta. LaAdministración de Impuestos rechazaparte de la deducción y notifica sanción.El caso deja al lector la tareade realizar el análisis que lleve aencontrar la solución que debe asumirla dirección de la compañía y queminimice costos y riesgos.Deducciones, Activos Fijos RealesProductivos, Inversión, RequerimientoEspecial, Declaración de Renta.