Competencias docentes en la era digital. La formación del pensamiento práctico

Las grandes transformaciones tecnológicas y las nuevas formas de concebir la enseñanza y el aprendizaje plantean la necesidad de volver a pensar el sentido y la naturaleza de la profesión docente. En este escenario, la investigación educativa se ha centrado en conocer cuáles son las competencias que los docentes necesitan para afrontar de manera satisfactoria los nuevos retos profesionales. Este artículo reflexiona, precisamente, acerca del sentido holístico del controvertido término competencias, sobre la selección de las que serían profesionalmente más sobresalientes y sobre los complejos procesos de formación de las mismas. Se destaca la importancia que adquieren el pensamiento práctico y el desarrollo de procesos de interacción entre la teoría y la práctica como marco privilegiado para la formación de competencias en el profesorado

Estado del magdalena: alumnos oficiales de la nación

Decreto por el cual se designan tres de los cuatro alumnos más que el Estado tiene derecho a enviar a la Universidad Nacional, de acuerdo con la lei nacional de 2 de junio de este año [1874], marcada con el número 94

Sulfite-reducing clostridia in the sediment of a high mountain lake (Laguna Grande, Gredos, Spain) as indicators of fecal pollution

We studied the vertical distribution of sulfite-reducing clostridia in the sediment of a Spanish high-mountain lagoon (Laguna Grande de Gredos, central Spain), with optimal sediment characteristics (temperature < 20°C) to maintain spores without growing. This allowed us to assess the original numbers of sulfite-reducing clostridia endospores settled, without postdepositional growing. Sulfite-reducing clostridia are normal inhabitants of the intestinal microbiota of humans and other mammals. These microorganisms may form endospores, which allow the bacteria to survive in almost any habitat, either terrestrial or aquatic, waiting for favorable conditions for growth. Sulfite-reducing clostridia could be suitable indicators of past human pollution because they have a great longevity in natural habitats and they cannot multiply at temperatures below 20°C or in the presence of O2. We found a great increase in the numbers of clostridia (expressed as colony-forming units per gram [CFU/g] of dry weight of sediment) since the 1970s, which reflects the rise of human pressure caused by the practice of outdoor activities.Clostridia CFU/g rose dramatically after the faulty operation of the depuration system of a mountain refuge built close to the lagoon. We compared the vertical distribution of clostridia CFU/g from Laguna Grande sediments with those from a neighbor lagoon (Laguna Cimera), which showed less tourist pressure and no direct disposal of sewage. Finally, we agree with the usefulness of the numbers of sulfitereducing clostridia as indicators of past pollution

Infiltración y redistribución de agua en perfiles de la zona no saturada en la cuenca alta del río Paez, Cartago

En Costa Rica, la entrada del agua al suelo y su movimiento dentro de él ha sido poco estudiado. Esta entrada de agua puede estudiarse en un espacio geográfico claramente definido como lo es la cuenca hidrográfica. Es por esto por lo que el primer capítulo de esta tesis se tituló ”Análisis cuantitativo de la morfometría de la cuenca alta del río Páez y su relación con el proceso de infiltración” y el cual mostró cómo las propiedades específicas de la forma de la cuenca pueden influenciar la entrada de agua por infiltración. La morfometría condiciona muchos de los procesos hidrológicos en una cuenca, y constituye el primer elemento que debe ser analizado para poder determinar la dinámica de la infiltración. El proceso de infiltración además de considerar las características de la forma de una cuenca hidrográfica, presentan dos etapas en su dinámica propia, la primera considera los elementos que condicionan la entrada de agua previo a que esta llegue al terreno y la segunda, la que ocurre al momento en que esta llega. Por esto, el segundo capítulo de esta tesis fue titulado “Modelización de la infiltración en suelos volcánicos agrícolas por lluvia mensual en la cuenca alta del río Páez, Cartago”. La dinámica de entrada de agua por infiltración en suelos depende de las etapas por las que ésta pasa durante el evento y lo cual está muy relacionado con los cambios de uso de la tierra, especialmente los usos agrícolas. La espacialidad del proceso de infiltración toma relevancia debido a que la combinación de los diferentes elementos resulta en diferentes rangos de infiltración en el suelo. Una vez que el proceso de infiltración ha terminado, el agua inicia un nuevo movimiento que depende de las propiedades de los horizontes de un perfil de suelo que en la mayoría de las veces se presenta no saturado. Este movimiento del agua no ha sido estudiado previamente en el país. Es por esto por lo que se desarrolló el tercer capítulo de esta tesis titulado “Redistribución de agua a través de perfiles de suelo de la zona no saturada bajo condiciones de uso agrícola en la cuenca alta del río Páez, Cartago” el cual analizó experimentalmente la dinámica del flujo de agua a través de los medios porosos que constituyen los horizontes de los suelos. Los resultados mostraron que temporalmente, luego de finalizada la infiltración, se da un movimiento de agua que viene a incrementar los contenidos de humedad de los horizontes en profundidad en diferentes momentos, demostrando así el flujo por redistribución.In Costa Rica, the entry into the water and its movement within the soil has been little studied. This water ingress occurs in a clearly defined geographical space as the watershed. Therefore, the first chapter of this thesis was titled “Quantitative Analysis of Morphometry of the upper Páez River Basin and its Relationship to the Infiltration Process” and which showed how the specific properties of the basin shape can influence it ingress of water by infiltration. Morphometry conditions many of the hydrological processes in a basin and is the first element that must be analyzed to determine the dynamics of infiltration. The infiltration process besides considering the characteristics of the shape of a watershed, presents two stages in its own dynamics, the first one considers the elements that condition the entry of water before it reaches the ground and the second, the one that happens when it arrives. For this reason, the second chapter of this thesis was entitled “Modeling infiltration of volcanic agricultural soils by monthly rainfall in the upper basin of the Páez River, Cartago”. The dynamics of soil infiltration water entry depend on the stages of the event and what is closely related to land use changes, especially agricultural uses. The spatiality of the infiltration process becomes relevant because the combination of the different elements results in different ranges of infiltration into the soil. Once the infiltration process is complete, the water starts a new movement that depends on the properties of the horizons of a soil profile that in most cases presents itself unsaturated. This movement of water has not been studied previously in the country. Therefore, the third chapter of this thesis entitled “Redistribution of water through soil profiles of the unsaturated zone under conditions of agricultural land use in the upper basin of the Páez River was developed. Cartago” which experimentally analyzed the dynamics of the flow of water through the porous media that constitute the horizons of the soils. The results showed that temporarily, after the infiltration is completed, there is a movement of water that increases the moisture content of the horizons in depth at different times, thus demonstrating the flow by redistribution.UCR::Vicerrectoría de Investigación::Sistema de Estudios de Posgrado::Ciencias Agroalimentarias::Doctorado en Ciencias Agrícola

Detection of Replay Attacks to GNSS based on Partial Correlations and Authentication Data Unpredictability

Intentional interference, and in particular GNSS spoofing, is currently one of the most significant concerns of the Positioning, Navigation and Timing (PNT) community. With the adoption of Open Service Navigation Message Authentication (OSNMA) in Galileo, the E1B signal component will continuously broadcast unpredictable cryptographic data. This allows GNSS receivers not only to ensure the authenticity of data origin but also to detect replay spoofing attacks for receivers already tracking real signals with relatively good visibility conditions. Since the spoofer needs to estimate the unpredictable bits introduced by OSNMA with almost zero delay in order to perform a Security Code Estimation and Replay (SCER) attack, the spoofer unavoidably introduces a slight distortion into the signal, which can be the basis of a spoofing detector. In this work, we propose five detectors based on partial correlations of GNSS signals obtained over predictable and unpredictable parts of the signals. We evaluate them in a wide set of test cases, including different types of receiver and spoofing conditions. The results show that one of the detectors is consistently superior to the others, and it is able to detect SCER attacks with a high probability even in favorable conditions for the spoofer. Finally, we discuss some practical considerations for implementing the proposed detector in receivers, in particular when the Galileo OSNMA message structure is used

Crotonaldehyde hydrogenation on Rh/TiO2 catalysts. In situ DRIFTS studies

The surface and catalytic properties in the vapor-phase hydrogenation of crotonaldehyde on Rh/TiO2 has been studied. It was found that a partial reduction of the support produces a surface decoration of the metal component. Thus, interfacial sites are created, which are responsible of an increase in the selectivity to crotyl alcohol, via enhancement of the polarization of the C=O bond. Photoelectron spectra revelead that rhodium is in different oxidation states, with a contribution of ca. 20 % Rhd + and 80 % Rhº species for LTR catalyst and only a slight increase of Rhd + for HTR catalyst. TEM studies revelead that Rh has metal particle size close 3 nm with small increases in the catalyst reduced at high temperature. DRIFTS essayed carried out under reaction conditions allowed to identify crotonaldehyde species strongly adsorbed through the C=C bond and weakly coordinated through both the C=C and C=O bonds. After reduction at 723 K an increase in the peak at 1660 cm-1 ascribed to an interaction between the carbonyl group and the surface, was observed. This peak seems to be stabilized at interfacial Rh/TiOx sites The deactivation in crotyl alcohol formation can be ascribed to the generation of strongly chemisorbed asymmetric carboxylate species detected by band at 1740 cm-1. This band grows at expense of crotonaldehyde O s - bonded intermediate chemisorbed on coordinatively unsaturated sites (Lewis acid sites) responsible of the crotyl alcohol obtaintion (detected by a band at 1653 cm-1). Additionally, a small band at 2068 cm-1 assigned to CO adsorbed on transition metals, which increases with time on-stream may explain the deactivation of the catalysts in flow systems

Effect of strain and magnetic field on the critical current and electric resistance of the joints between HTS coated conductors

Engineering of devices and systems such as magnets, fault current limiters or cables, based on High Temperature Superconducting wires requires a deep characterization of the possible degradation of their properties by handling at room temperature as well as during the service life thus establishing the limits for building up functional devices and systems. In the present work we report our study regarding the mechanical behavior of spliced joints between commercial HTS coated conductors based on YBCO at room temperature and service temperature, 77 K. Tensile tests under axial stress and the evolution of the critical current and the electric resistance of the joints have been measured. The complete strain contour for the tape and the joints has been obtained by using Digital Image Correlation. Also, tensile tests under external magnetic field have been performed and the effect of the applied field on the critical current and the electric resistance of the joints has been studied. Additionally, fatigue tests under constant cyclic stress and loading-unloading ramps have been carried out in order to evaluate the electromechanical behavior of the joints and the effect of maximum applied stress on the critical current. Finally, a preliminary numerical study by means of the Finite Element Method (FEM) of the electromechanical behavior of the joints between commercial HTS is presented

Effect of strain and magnetic field on the critical current and electric resistance of the joints between HTS coated conductors

Engineering of devices and systems such as magnets, fault current limiters or cables, based on High Temperature Superconducting wires requires a deep characterization of the possible degradation of their properties by handling at room temperature as well as during the service life thus establishing the limits for building up functional devices and systems. In the present work we report our study regarding the mechanical behavior of spliced joints between commercial HTS coated conductors based on YBCO at room temperature and service temperature, 77 K. Tensile tests under axial stress and the evolution of the critical current and the electric resistance of the joints have been measured. The complete strain contour for the tape and the joint has been obtained by using Digital Image Correlation. Also, tensile tests under external magnetic field have been performed and the effect of the applied field on the critical current and the electric resistance of the joints has been studied. Finally, a preliminary numerical study by means of Finite Element Method (FEM) of the mechanical behavior of the joints between commercial HTS is presented