Proposal for a three-dimensional magnetic measurement method with nanometer-scale depth resolution

We propose a magnetic measurement method based on combining depth sectioning and electron magnetic circular dichroism in scanning transmission electron microscopy. Electron vortex beams with large convergence angles, as those achievable in current state-of-the-art aberration correctors, could produce atomic lateral resolution and depth resolution below 2~nm.Comment: 5 pages, 3 figure

On-column 2p bound state with topological charge \pm1 excited by an atomic-size vortex beam in an aberration-corrected scanning transmission electron microscope

Atomic-size vortex beams have great potential in probing materials' magnetic moment at atomic scales. However, the limited depth of field of vortex beams constrains the probing depth in which the helical phase front is preserved. On the other hand, electron channeling in crystals can counteract beam divergence and extend the vortex beam without disrupting its topological charge. Specifically, in this paper, we report atomic vortex beams with topological charge \pm1 can be coupled to the 2p columnar bound states and propagate for more 50 nm without being dispersed and losing its helical phase front. We gave numerical solutions to the 2p columnar orbitals and tabulated the characteristic size of the 2p states of two typical elements, Co and Dy, for various incident beam energies and various atomic densities. The tabulated numbers allow estimates of the optimal convergence angle for maximal coupling to 2p columnar orbital. We also have developed analytic formulae for beam energy, convergence-angle, and hologram dependent scaling for various characteristic sizes. These length scales are useful for the design of pitch-fork apertures and operations of microscopes in the vortex-beam imaging mode.Comment: 30 pages, 7 figures, Microscopy and Microanalysis, in pres

Fast brain decoding with random sampling and random projections

International audienceMachine learning from brain images is a central tool for image-based diagnosis and diseases characterization. Predicting behavior from functional imaging, brain decoding, analyzes brain activity in terms of the behavior that it implies. While these multivariate techniques are becoming standard brain mapping tools, like mass-univariate analysis, they entail much larger computational costs. In an time of growing data sizes, with larger cohorts and higher-resolutions imaging, this cost is increasingly a burden. Here we consider the use of random sampling and projections as fast data approximation techniques for brain images. We evaluate their prediction accuracy and computation time on various datasets and discrimination tasks. We show that the weight maps obtained after random sampling are highly consistent with those obtained with the whole feature space, while having a fair prediction performance. Altogether, we present the practical advantage of random sampling methods in neuroimaging, showing a simple way to embed back the reduced coefficients, with only a small loss of information

Evolution of the concepts and paradigms that guide the environmental management; what are their limitations in the glocal context?

In this article was made an analysis of the chronological evolution of different paradigms and concepts related to the environmental management (EM). the review highlights those that have impacts on the guidance of the EM in the country and the concept of associated development, as well as the considered approaches and dimensions for establishing the relations between them. Although the environmental management is one of the public functions shared with the society, the implemented model of EM has been unidirectional and this limited the inter institutional interaction with the communities and the interdisciplinary relations. If this situation have a glocal-logic point of view in different ecosystems and regions, the predominance of the economic growth approach is evident with a low interaction between know-how and knowledge, that circumstance restrict the construction of sustainable management alternatives and generate environmental actions isolated. Key words: management, ecosystems, environment, paradigm. Key words: management, ecosystems, environment,paradigm.El presente artículo aborda la evolución cronológica de diferentes paradigmas y conceptos relacionados con la gestión ambiental (GA). Para ello, hace énfasis en aquellos que han incidido en la dirección de la GA en el país, e identifica el concepto de desarrollo asociado, así como los planteamientos y dimensiones considerados para establecer las relaciones existentes entre los mismos. Si bien la gestión ambiental es una de las funciones públicas compartidas solidariamente con la sociedad, su implementación ha sido unidireccional, lo que ha promovido modelos homogeneizadores que limitan la interacción con las comunidades y las relaciones interinstitucionales e interdisciplinarios. Si se observa esta situación desde una lógica glocal en diferentes ecosistemas y regiones, es evidente el predominio del enfoque de crecimiento económico con una escasa interacción entre saberes y conocimiento, situación que limita la construcción de alternativas de manejo sostenible y desencadena acciones ambientales desarticuladas

El universo mágico de los cuentos de hadas. Secuencia didáctica para la comprensión lectora en cuentos maravillosos

El presente proyecto se hace con el fin de fortalecer la comprensión lectora en estudiantes de grado tercero de la Institución educativa Inem Felipe Pérez de la ciudad de Pereira. Utilizando textos narrativos en este caso se centró primeramente en los cuentos de hadas y el mundo maravillo para que los niños tengan una mejor relación con los textos narrativos. Para tal fin se elaboró una secuencia de ocho sesiones pedagógicas para abordar el cuento Maschenka y el oso, fundamentado en los conceptos de literatura fantástica de Todorov, secuencia didáctica de Camps y concepción del lenguaje desde Vygotsky

Crisis de la deuda en las empresas municipales de Cali y perspectivas

Emcali es una Empresa Industrial y Comercial del Estado, la principal entidad descentralizada del municipio de Cali; actualmente, y desde abril de 2000, se encuentra intervenida por la Superintendencia de Servicios Públicos Domiciliarios, por lo cual debe resolver antes de abril del año 2002 los problemas financieros que amenazan la viabilidad en su actividad económica, consistente en la prestación de los servicios de acueducto, alcantarillado, energía y telecomunicaciones.Empresas Públicas, Emcali, deuda

Improving sparse recovery on structured images with bagged clustering

International audience—The identification of image regions associated with external variables through discriminative approaches yields ill-posed estimation problems. This estimation challenge can be tackled by imposing sparse solutions. However, the sensitivity of sparse estimators to correlated variables leads to non-reproducible results, and only a subset of the important variables are selected. In this paper, we explore an approach based on bagging clustering-based data compression in order to alleviate the instability of sparse models. Specifically, we design a new framework in which the estimator is built by averaging multiple models estimated after feature clustering, to improve the conditioning of the model. We show that this combination of model averaging with spatially consistent compression can have the virtuous effect of increasing the stability of the weight maps, allowing a better interpretation of the results. Finally, we demonstrate the benefit of our approach on several predictive modeling problems