11 resultados para 74798


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In response to the rail industry lacking a consistently accepted standard of minimal training to perform incident investigations, the Australasian rail industry requested the development of a unified approach to investigator training. This paper details how the findings from a training needs analysis were applied to inform the development of a standardised training package for rail incident investigators. Data from job descriptions, training documents and subject matter experts sourced from 17 Australasian organisations were analysed and refined to yield a draft set of 10 critical competencies. Finally the draft of critical competencies was reviewed by industry experts to verify the accuracy and completeness of the competency list and to consider the most appropriate level of qualification for training development. The competencies identified and the processes described to translate research into an applied training framework in this paper, can be generalised to assist practitioners and researchers in developing industry approved standardised training packages.

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Se exponen una serie de consideraciones generales sobre investigación educativa. El objetivo es motivar al profesorado sobre los métodos activos en la enseñanza, estimulándole a dar respuestas nuevas a los problemas cotidianos que se presentan en el ejercicio de la actividad docente. Para ello, se presentan tres ejemplos de experiencias didácticas en Matemáticas realizadas con alumnos de Bachillerato, con la intención de que puedan servir a los profesores como sugerencias para emprender otras acciones.

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Yttrium manganite (YMnO3) is a multiferroic material, which means that it exhibits both ferromagnetic and ferroelectric properties, so making it interesting for a variety of technological applications. In this work, single-phase YMnO3 was prepared for the first time by mechanochemical synthesis in a planetary ball mill. The YMnO3 was formed directly from the highly activated constituent oxides, Y 2O3 and Mn2O3, after 60 min of milling time. During prolonged milling, the growth of the particles occurred. The cumulative energy introduced into the system during milling for 60 min was 86 kJ/g. The X-ray powder-diffraction analysis indicates that the as-prepared samples crystallize with an orthorhombic (Pnma) YMnO3 structure. The morphology and chemical composition of the powder were investigated by SEM and FESEM. The magnetic properties of the obtained YMnO3 powders were found to change as a function of the milling time in a manner consistent with the variation in the nanocomposite microstructure. © 2012 Elsevier B.V. All rights reserved.

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Water-containing biological material cannot withstand the vacuum of the transmission electron microscope. The classical solution to this problem has been to dehydrate chemically fixed biological samples and then embed them in resin. During such treatment, the bacterial nucleoid is especially prone to aggregation, which affects its global shape and fine structure. Initial attempts to deal with aggregation by optimizing chemical fixation yielded contradictory results. Two decades ago, the situation improved with the introduction of freeze-substitution. This method is based on dehydration of unfixed cryo-immobilized samples at low temperature, which substantially reduces aggregation. As a result, the global shape of the nucleoid can be fairly well defined. Overall, in actively growing bacteria, the nucleoids are dispersed and "coralline" but become more confined when growth ceases. However, it is usually impossible to determine the molecular arrangement of DNA in the nucleoids of freeze-substituted bacteria because crystallization and the subsequent removal of water during substitution result in unavoidable distortions at the ultrastructural level. Recently, cryo-electron microscopy of vitreous sections has enabled the fully hydrated bacterial nucleoid to be studied close to the native state. Such studies have revealed aspects of bacterial nucleoid organization that are not preserved by freeze-substitution, including locally parallel or twisted bundles of DNA filaments, which are more frequently observed once bacterial growth has stopped, whereas in actively growing bacteria, the DNA is seen to be in a mostly disordered pattern.

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