Cycloidal Domains in the Magnetization Reversal Process of Ni80Fe20/Nd16Co84/Gd12Co88 Trilayers

The magnetization reversal of each individual layer in magnetic trilayers ( permalloy / Nd Co / Gd Co ) is investigated in detail with x-ray microscopy and micromagnetic calculations. Two sequential inversion mechanisms are identified. First, magnetic vortex-antivortex pairs move along the field direction while inverting the magnetization of magnetic stripes until they are pinned by defects. The vortex-antivortex displacements are reversible within a field interval which allows their controlled motion. Second, as the reversed magnetic field increases, cycloidal domains appear in the permalloy layer as a consequence of the dissociation of vortex-antivortex pairs due to pinning. The field range where magnetic vortices and antivortices are effectively guided by the stripe pattern is of the order of tens of mT for the Ni Fe layer, as estimated from the stability of cycloid domains in the sample

Variación fenológica de Rhizophora mangle, Conocarpus erectus y Laguncularia racemosa en Isla Múcura, Parque Nacional Natural Los Corales del Rosario y de San Bernardo, Caribe colombiano

Mangroves are strategic coastal marine ecosystems with a wide variety of services to humanity. However, they are vulnerable to natural and anthropogenic disturbances, being fragmentation a more significant threat. Consistent with the above, the Corales del Rosario y de San Bernardo (PNNCRSB) have been identified as a conservation object value of the PNN. The most common mangrove species at PNNCRSB are the red mangrove Rhizophora mangle, the Zaragoza Conocarpus erectus, and the yellow Laguncularia racemosa. Currently, the available information and the monitoring program for this protected area are limited to coverage data, so there is limited information available on the phenology of these species, despite knowing that the latter responds to environmental changes in the ecosystem. Therefore, this research aimed to evaluate the variation of phenological events (production of fruits, flowers, and leaves) of red, zaragoza and yellow mangroves in the PNNCRSB for two years and its relationship with intra-annual climatic patterns. The results show that there are temporal patterns of the variation of the phenological events.  In the case of R. mangle, it did not show leaf drops but presented fruits and flowers during the 24 months. Something similar was observed for C. erectus. Robust and significant canonical correlations (R >6; p <0.05) were also found for groups of climatic environmental variables and phenological events in the three species in the two years of study. Therefore, it is inferred that there are suitable environmental conditions for mangroves development and the climatic patterns affect the phenology of the species in the study area. Finally, phenological characteristics of the species are proposed as an important input for decision making such as restoration processes, since they allow knowing the periods of time indicated to carry out activities of collecting propagules, setting up nurseries and planting seedlings in degraded areas.Los manglares son ecosistemas marino costeros estratégicos ofrecen una variedad de servicios a la humanidad. No obstante, son vulnerables a perturbaciones naturales y antropogénicas, dentro de las cuales la fragmentación representa una mayor amenaza. Consecuente con lo anterior, han sido identificados como valor objeto de conservación del PNN Los Corales del Rosario y de San Bernardo (PNNCRSB), siendo las especies más representativas el mangle rojo Rhizophora mangle, el zaragoza Conocarpus erectus y el amarillo Laguncularia racemosa. Actualmente, la información existente y el programa de monitoreo de esta área protegida se limita a datos de coberturas, por lo que no existe información disponible sobre la fenología de estas especies. Por lo anterior, esta investigación se propuso evaluar la variación de eventos fenológicos (producción de frutos, flores y hojas) de mangle rojo, zaragoza y amarillo en el PNNCRSB durante 2014-2015 y su relación con patrones climáticos intra-anuales. Los resultados muestran que existen patrones temporales de la variación de los eventos fenológicos. En el caso de R. mangle, no evidenció caída de hojas, pero sí presentó frutos y flores durante los 24 meses. Algo similar se observó para C. erectus. También se encontraron correlaciones canónicas robustas y significativas (R > 6; p <0,05) de grupos de variables ambientales climáticas y los eventos fenológicos en las tres especies en los dos años de estudio. Con lo anterior se infiere que existen condiciones ambientales idóneas para su desarrollo y que los patrones climáticos inciden sobre la fenología de las especies de mangle en el área de estudio. Finalmente, las características fenológicas de las especies se proponen como insumo importante para la adopción de medidas de manejo como procesos de restauración, pues permiten conocer los periodos de tiempo indicados para realizar actividades de recolecta de propágulos, montaje de viveros y siembra de plántulas en zonas degradadas

High pressure and temperature spinning capillary cell for in-situ synchrotron X-ray powder diffraction

In situ research of materials under moderate pressures (hundreds of bar) is essential in many scientific fields. These range from gas sorption to chemical and biological processes. One industrially important discipline is the hydration of oil well cements. Existing capillary cells in this pressure range are static as they are easy to design and operate. This is convenient for the study of single-phase materials; however, powder diffraction quantitative analyses for multiphase systems cannot be performed accurately as a good powder average cannot be attained. Here, the design, construction and commissioning of a cost-effective spinning capillary cell for in situ powder X-ray diffraction is reported, for pressures currently up to 200 bar. The design addresses the importance of reducing the stress on the capillary by mechanically synchronizing the applied rotation power and alignment on both sides of the capillary while allowing the displacement of the supports needed to accommodate different capillaries sizes and to insert the sample within the tube. This cell can be utilized for multiple purposes allowing the introduction of gas or liquid from both ends of the capillary. The commissioning is reported for the hydration of a commercial oil well cement at 150 bar and 150°C. The quality of the resulting powder diffraction data has allowed in situ Rietveld quantitative phase analyses for a hydrating cement containing seven crystalline phases.The design, production and commissioning of this cell was carried out at the ALBA synchrotron as part of Edmundo Fraga’s PhD project. This work was financially supported by the Spanish Ministry of Economy and Competitiveness through Grants BIA2014-57658-C2-1-R and BIA2017-82391-R which are co-funded by FEDER. We are grateful to Prof. Angus Wilkinson, Georgia Institute of Technology Atlanta, for sharing his knowledge and details on the high pressure cell developed by his team. We also thank Dr. Marcus Paul, Dyckerhoff-Lengerich, Germany, for fruitful discussion on Oil Well Cements. The cell was commissioned at BL11-NCD-SWEET beamline

A 3D Cartographic Description of the Cell by Cryo Soft X-ray Tomography

Imaging techniques are fundamental in order to understand cell organization and machinery in biological research and the related fields. Among these techniques, cryo soft X-ray tomography (SXT) allows imaging whole cryo-preserved cells in the water window X-ray energy range (284-543 eV), in which carbon structures have intrinsically higher absorption than water, allowing the 3D reconstruction of the linear absorption coefficient of the material contained in each voxel. Quantitative structural information at the level of whole cells up to 10 µm thick is then achievable this way, with high throughput and spatial resolution down to 25-30 nm half-pitch. Cryo-SXT has proven itself relevant to current biomedical research, providing 3D information on cellular infection processes (virus, bacteria, or parasites), morphological changes due to diseases (such as recessive genetic diseases) and helping us understand drug action at the cellular level, or locating specific structures in the 3D cellular environment. In addition, by taking advantage of the tunable wavelength at synchrotron facilities, spectro-microscopy or its 3D counterpart, spectro-tomography, can also be used to image and quantify specific elements in the cell, such as calcium in biomineralization processes. Cryo-SXT provides complementary information to other biological imaging techniques such as electron microscopy, X-ray fluorescence or visible light fluorescence, and is generally used as a partner method for 2D or 3D correlative imaging at cryogenic conditions in order to link function, location, and morphology

Comunicación y polialfabetismo Aportes desde el saber pedagógico para la educación del siglo XXI

144 páginas. Libro electrónicoLa línea de Comunicación y polialfabetismos presenta en las experiencias de aula un abanico de posibilidades didácticas que se desarrollan en las instituciones educativas en las que laboran los maestros participantes del programa “Maestros y Maestras que Inspiran”. Además, en el uso de diversos modos expresivos para interactuar, aprender y comunicar. Es de resaltar que tienen interés por potenciar los aprendizajes de los estudiantes a partir de propuestas que involucran sus intereses, necesidades y problemáticas del contexto; es decir, son seres dialógicos (Freire, 1973) que tienden puentes entre el conocimiento, las problemáticas y las posibilidades para narrar, expresar, dramatizar, exponer, cantar y representar la realidad a través de diversas formas de comunicación con el fin de transformarla.Primera edición, 202

Definición de un proceso de gestión de la innovación docente en la Universidad de Salamanca sobre la base de un sistema integral de gestión del conocimiento

Memoria ID-0045. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2015-2016

Implantación de un sistema integral de gestión del conocimiento para los procesos de innovación docente de la Universidad de Salamanca

Memoria ID-0312. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2014-2015

Implantación de un sistema integral de gestión del conocimiento para los procesos de innovación docente de la Universidad de Salamanca

Memoria ID-0312. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2014-2015

Enfoque estratégico de oscilación unilateral

This paper reports an approach developed to find a good quality solution for a generalized assignment problem with application to the Dimensional Cutting Problem. The objective at the Cutting Problemis to divide different pools of pieces of the same dimension among different items of available material all having two dimensions, the width and length. The solution is found keeping the largest number of pieces in a single material. Some initial numerical experiences found for the algorithm optimal and suboptimal solutions orinstances of more than 500 pieces at a very low computational cost.El presente artículo presenta un enfoque desarrollado para en-contrar una solución de alta calidad para un problema de asignacióngeneralizado con aplicaciones al Problema de Cortes Dimensionales.El objetivo en el Problema de Cortes es dividir diferentes juegos depiezas de las mismas dimensiones dentro de varios artículos de ma-terial disponible, teniendo ambos dos dimensiones: ancho y largo.La solución es tomada manteniendo el mayor número de piezas enun sólo material. Algunas experiencias numéricas encontraron solu-ciones óptimas y cuasi-óptimas para el algoritmo en no más de 500piezas con un costo computacional bajo