995 resultados para Digital radiography


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The increasing availability of large, detailed digital representations of the Earth’s surface demands the application of objective and quantitative analyses. Given recent advances in the understanding of the mechanisms of formation of linear bedform features from a range of environments, objective measurement of their wavelength, orientation, crest and trough positions, height and asymmetry is highly desirable. These parameters are also of use when determining observation-based parameters for use in many applications such as numerical modelling, surface classification and sediment transport pathway analysis. Here, we (i) adapt and extend extant techniques to provide a suite of semi-automatic tools which calculate crest orientation, wavelength, height, asymmetry direction and asymmetry ratios of bedforms, and then (ii) undertake sensitivity tests on synthetic data, increasingly complex seabeds and a very large-scale (39 000km2) aeolian dune system. The automated results are compared with traditional, manually derived,measurements at each stage. This new approach successfully analyses different types of topographic data (from aeolian and marine environments) from a range of sources, with tens of millions of data points being processed in a semi-automated and objective manner within minutes rather than hours or days. The results from these analyses show there is significant variability in all measurable parameters in what might otherwise be considered uniform bedform fields. For example, the dunes of the Rub’ al Khali on the Arabian peninsula are shown to exhibit deviations in dimensions from global trends. Morphological and dune asymmetry analysis of the Rub’ al Khali suggests parts of the sand sea may be adjusting to a changed wind regime from that during their formation 100 to 10 ka BP.

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This paper describes a study of digital literacy where the researcher worked with one group of English language arts teacher candidates and one of adolescents, reading and writing hypertext fiction. The findings suggest that the adolescent readers/writers brought a more flexible and multiliterate approach to their digital literacy processes than the teacher candidates.

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Protons accelerated by a picosecond laser pulse have been used to radiograph a 500 mu m diameter capsule, imploded with 300 J of laser light in 6 symmetrically incident beams of wavelength 1.054 mu m and pulse length 1 ns. Point projection proton backlighting was used to characterize the density gradients at discrete times through the implosion. Asymmetries were diagnosed both during the early and stagnation stages of the implosion. Comparison with analytic scattering theory and simple Monte Carlo simulations were consistent with a 3 +/- 1 g/cm(3) core with diameter 85 +/- 10 mu m. Scaling simulations show that protons > 50 MeV are required to diagnose asymmetry in ignition scale conditions.

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This paper addresses the issue of the digital divide in students of public secondary schools at Chihuahua City, Mexico. It seeks to identify potential inequality of opportunities with regards to subjects’ access to information, knowledge and education through the ICT (internet, mobile telephony, broadband and television). The study takes three schools as investigative stage, using the survey as a data collection instrument, identifying patterns of behavior regarding: general knowledge of them, access to computer equipment and internet, and characterization of their use. Other aspects of analysis are the identification of the educational level of parents and access to technology resources available for academic and non-academic purposes in various application areas (home, school and social environment). The proposal concludes, that it is through the recollection of alternatives suggested by the teachers themselves to incorporate ICT for teaching purposes in a systematic and planned fashion, whose greatest reflection manifests in better digital literacy indicators.

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In this paper we discuss collaborative learning strategies based on the use of digital stories in corporate training and lifelong learning. The text starts with a concise review on theoretical and technical foundations about the use of digital technologies in collaborative strategies in lifelong learning. We will also discuss if the corporate training may be improved by the use of individual audio-visual experience in learning process. Careful planning, scripting and production of audio-visual digital stories can help in the construction of collaborative learning spaces in which adults are in the context of vocational training throughout life. Our analysis concludes emphasizing on the need to experience the routing performance of digital stories in the context of corporate training, following the reference levels mentioned here, so we can have in a future more theoretical and empirical elements for the validation and conceptualization in the use of digital stories in the context of corporate training. Ultimately we believe that lifelong learning can be improved with the use of strategies that promote the production of personal audio-visual for those involved in teaching and learning process in organizational context.