BROA: An agent-based model to recommend relevant Learning Objects from Repository Federations adapted to learner profile

Learning Objects (LOs) are distinguished from traditional educational resources for their easy and quickly availability through Web-based repositories, from which they are accessed through their metadata. In addition, having a user profile allows an educational recommender system to help the learner to find the most relevant LOs based on their needs and preferences. The aim of this paper is to propose an agent-based model so-called BROA to recommend relevant LOs recovered from Repository Federations as well as LOs adapted to learner profile. The model proposed uses both role and service models of GAIA methodology, and the analysis models of the MAS-CommonKADS methodology. A prototype was built based on this model and validated to obtain some assessing results that are finally presented

Managing Vegetation In Grassland Habitats To Enhance Livestock Or Wildlife Objectives

Sustainably stewarding grassland systems involves applying various practices to manipulate forage interactions with other plants, the environment, and grazing animals to meet resource manager objectives. These interactions can result in invasion or encroachment and increased abundance of weeds which hinder attainment of management objectives. Weeds influence the structure and function of pasture ecosystems whether forages are grown in improved pastures, rangeland, or grassland communities. They degrade pasture quality and reduce livestock performance by interfering with forage establishment, yield, and quality by competing for resources. Weeds reduce the feed value of forage, decrease pasture carrying capacity, and can be toxic or unpalatable to livestock. Managing weeds requires use of vegetation management tools that favor desirable forages. Herbicides can be a catalyst that expedite grassland renovation, improve the forage resource, and increase carrying capacity. Corteva Agriscience has a variety of herbicide products that provide superior control of herbaceous and woody weeds, while maintaining the desirable vegetation. These herbicides were designed and developed specifically for selective broadleaf weed control in rangeland, pastures, rights-of-way, non-cropland, and natural areas. Active ingredients historically used include aminopyralid, triclopyr, fluroxypyr, clopyralid, and picloram. Rinskor™ active and Arylex™ active are new herbicide active ingredients from Corteva Agriscience™ and are members of a unique synthetic auxin chemotype, the arylpicolinates (HRAC group O / WSSA group 4). Members of the arylpicolinate family demonstrate novel and differentiated characteristics in terms of use rate, spectrum, weed symptoms, environmental fate, and molecular interaction as compared to other auxin chemotypes. When applied as a stand-alone treatment or in various mixes these products are safe to desirable grass species and control key herbaceous and woody weeds in the genera Ambrosia, Acacia, Carduus, Centaurea, Cirsium, Mimosa, Prosopis, Ranunculus, Rumex, Sida, Solanum, Taraxacum, and more

On the validity of the 5-dimensional Birkhoff theorem: The tale of an exceptional case

The 5-dimensional (5d) Birkhoff theorem gives the class of 5d vacuum space-times containing spatial hypersurfaces with cosmological symmetries. This theorem is violated by the 5d vacuum Gergely-Maartens (GM) space-time, which is not a representant of the above class, but contains the static Einstein brane as embedded hypersurface. We prove that the 5d Birkhoff theorem is still satisfied in a weaker sense: the GM space-time is related to the degenerated horizon metric of certain black-hole space-times of the allowed class. This result resembles the connection between the Bertotti-Robinson space-time and the horizon region of the extremal Reissner-Nordstrom space-time in general relativity.Comment: 13 pages; v2: title amended, to be published in Classical and Quantum Gravit

Sistema de e-Learning ubicuo, sensible al contexto y personalizado para ambientes virtuales de aprendizaje

La mayoría de los ambientes virtuales de aprendizaje actuales, no presentan características de personalización de contenidos, es decir, no consideran las necesidades y gustos de los estudiantes lo que genera desinterés por parte de estos y retrasa notoriamente el proceso de aprendizaje. Otra falencia evidente en este tipo de sistemas es la incapacidad de ofrecer servicios que permitan al estudiante llevar control de las actividades ligadas al proceso de aprendizaje tales como recepción de alertas inmediatas asociadas a la finalización de tareas, activación de nuevas actividades de aprendizaje, recomendación de asistentes, etc. El objetivo de este artículo es desarrollar un módulo de servicios de awareness que busca orientar y sensibilizar a los estudiantes respecto a su desempeño, presentándoles en tiempo real un historial de las actividades realizadas en su proceso de enseñanza-aprendizaje mientras utilizan el entorno virtual de aprendizaje. Cabe señalar que este módulo es integrado a un sistema multi-agente personalizado de planificación instruccional y recomendación de recursos educativos. Las metodologías empleadas en esta investigación son Prometheus, para la construcción del sistema multi-agente ubicuo y sensible al contexto, y Methontology, para el desarrollo de la ontología que representa el conocimiento del dominio de los Cursos Virtuales Adaptativos, así como de los perfiles de usuario. Cada uno de los servicios de awareness propuestos fue implementado y validado mediante un caso de estudio que demostró las ventajas que trae la utilización de este tipo de mecanismos sensibles al contexto en entornos virtuales de aprendizaje

SERVICIO WEB PARA RECOMENDACIÓN EN LA FEDERACIÓN DE REPOSITORIOS DE OBJETOS DE APRENDIZAJE COLOMBIA

La federación de repositorios de objetos de aprendizaje Colombia (FROAC) permite acceder a Objetos de Aprendizaje (OA) almacenados en diferentes repositorios afiliados a la federación a través de búsquedas sencillas y avanzadas. El objetivo de este artículo es entregar OA adaptados a las preferencias y necesidades de los usuarios de la federación, integrando un sistema híbrido de recomendación de OA, que permite filtrar los resultados de una búsqueda y entregar primero aquellos OA que se ajusten mejor a las características del usuario. Para dicha integración se implementó un servicio web que permite la comunicación entre la federación y el sistema de recomendación. Los resultados permiten concluir que el sistema de recomendación en FROAC permite visualizar los OA que se adaptan a un usuario mejorando la precisión en cuanto a la relevancia de los resultados y que los servicios web son un mecanismo que facilita su implementación

Thiamethoxam in Papaya (Carica papaya Linnaeus) Agroecosystems

Papaya (Carica papaya L.) is a profitable fruit of economic and food importance in Mexico and Central America. Veracruz is the state in Mexico with the highest cultivable area, eventhough its production presents numerous phytosanitary problems, which are being faced with the use of the pesticide thiamethoxam. The aim of this study was to make a diagnosis of the use and management of thiamethoxam in papaya agroecosystems in the municipality of Cotaxtla, Veracruz. Two surveys were applied, one to a 30% of the total number of producers organized by an association dedicated to papaya culture, and the other survey was through key informants, both surveys were designed using the snowball sampling, a non-probability sampling technique. The results indicate that 6% of papaya producers use mainly the pesticide thiamethoxam, which belongs to the chemical group of neonicotinoids. It was found out that for five years there have been records of thiamethoxam use in vertisoils. During the cycle of papaya cultivation the producers use a maximum dose of 3 L/ha and a minimum dose of 250 ml/ha per crop cycle. One hundred per cent of those who apply thiamethoxam are not aware of its use and efficient management, nor of the damage they are doing or have caused to agroecosystems

Hybrid nanomembranes for high power and high energy density supercapacitors and their yarn application

Ultrathin (thicknessnm) electrically conducting membranes can be used as electrodes for sensors, actuators, optical devices, fuel cells, scaffolds for assembling nanoparticles, and separation of biological macromolecules.1-6 Various approaches have been suggested for the fabrication of free-standing nanomembranes based on organic polymers and/or inorganic materials: spin-casting of films,7 layer-by-layer assembly of polyelectrolyte multilayers,8 cross-linking of self-assembled monolayers,9 and assembly of triblock copolymers.10,11 Loading materials such as gold nanoparticles12 or carbon nanotubes13 make membranes robust and electrically conductive. However, these methods are often time-consuming and have some limitations in terms of achievable electrical and electrochemical membrane performance as well as scale-up. Alternative approaches are needed for the preparation of mechanically robust, free-standing, conductive nanomembranes that could be easily manufactured

Constraints on the braneworld from compact stars

According to the braneworld idea, ordinary matter is confined on a three-dimensional space (brane) that is embedded in a higher-dimensional space-time where gravity propagates. In this work, after reviewing the limits coming from general relativity, finiteness of pressure and causality on the brane, we derive observational constraints on the braneworld parameters from the existence of stable compact stars. The analysis is carried out by solving numerically the brane-modified Tolman–Oppenheimer–Volkoff equations, using different representative equations of state to describe matter in the star interior. The cases of normal dense matter, pure quark matter and hybrid matter are considered.info:eu-repo/semantics/publishedVersio

Magnetized Particle Capture Cross Section for Braneworld Black Hole

Capture cross section of magnetized particle (with nonzero magnetic moment) by braneworld black hole in uniform magnetic field is considered. The magnetic moment of particle was chosen as it was done by \citet{rs99} and for the simplicity particle with zero electric charge is chosen. It is shown that the spin of particle as well as the brane parameter are to sustain the stability of particles circularly orbiting around the black hole in braneworld i.e. spin of particles and brane parameter try to prevent the capture by black hole.Comment: 7 pages, 4 figures, Accepted for publication in Astrophysics & Space Scienc