Multi-state Boson Stars

Motivated by the increasing interest in models which consider scalar fields as viable dark matter candidates, we have constructed a generalization of relativistic Boson Stars (BS) composed of two coexisting states of the scalar field, the ground state and the first excited state. We have studied the dynamical evolution of these Multi-state Boson Stars (MSBS) under radial perturbations, using numerical techniques. We show that stable MSBS can be constructed, when the number of particles in the first excited state, N2, is smaller than the number of particles in the ground state, N1. On the other hand, when N2 > N1, the configurations are initially unstable. However, they evolve and settle down into stable configurations. In the stabilization process, the initially ground state is excited and ends in a first excited state, whereas the initially first excited state ends in a ground state. During this process, both states emit scalar field radiation, decreasing their number of particles. This behavior shows that even though BS in the first excited state are intrinsically unstable under finite perturbations, the configuration resulting from the combination of this state with the ground state produces stable objects. Finally we show in a qualitative way, that stable MSBS could be realistic models of dark matter galactic halos, as they produce rotation curves that are flatter at large radii than the rotation curves produced by BS with only one state.Comment: 14 pages. Extended discussion and new figures added. Conclusions unchanged. Accepted for publication in Physical Review

E-commerce and territorial development in the Objective-1 spanish regions

The information and communication technologies constitute one of the main forces of the globalization. In this framework, the e-commerce takes advantage of Internet to improve the competitiveness of the companies and territories. In the nowadays scenario, the e-commerce opens development posibilities for the regions fewer developed, creating a virtual space that saves the geographical barriers. However, the use of its advantages requires infrastructures and equipment, organizational capacity and high formation in new technologies. In spite of the deficit that the objetive 1 spanish regions show in these fields to develop the their own Information Society, the attitude and the efforts of the public and private agents in improving their position in the national and international context, they open optimistic expectations on the future use of the advantages that the e-commerce offers for the growth and the improvement of the regional competitiveness in Spain. Nevertheless, one cannot hope the e-commerce is a decisive element to eliminate the territorial inequalities, not even the technologies of the information in its group, but rather it can be that they originate a restructuring of the spanish and european territorial pattern, where some regions will be able to improve thanks to the extension and deeping of the digital economy and others will worsen its position in the territorial system. In any event, the developed regions leave of a better position. All the analysts coincide in pointing out that the e-commerce is in an incipient phase, for what es expected that its growth in next years is very important. In this sense, this communication seeks to analyze the use of the possibilities that the e-commerce offers as tool of improvement of the competitiveness in the objetive 1 spanish regions in the framework of the regional development. To get this objetive, the theoretical linkings are revised among the new information and communication technologies, that allow the use of Internet like a trade channel, and the territorial development, showing the different focuses with those that are come approaching the influences of the Information Society on the regional competitiveness. Also, the current situation and perspectives of the objetive one spanish regions are rewied to face the challenges that outline the technological advances in this field in three environments: infrastructures and equipment; organization, support institutions and administration initiatives; and innovation, knowledge and formation.

Problemas de ecuaciones de primer grado con una incógnita

La utilización de recursos visuales y manipulativos potencializan nuestra capacidad para resolver problemas mediante ecuaciones de primer grado con una incógnita

Implementación de una secuencia didáctica, de enfoque comunicativo, en la producción escrita de resúmenes en inglés, con estudiantes de una universidad oficial de Pereira

Este estudio buscaba analizar la incidencia que genera la implementación de una Secuencia Didáctica (SD), de enfoque comunicativo, en la producción de resúmenes de textos expositivos, en los estudiantes de nivel intermedio de inglés de la Universidad Tecnológica de Pereira. Para este propósito, se llevó a cabo un estudio cuantitativo, con un diseño cuasi-experimental intragrupo, en el que participaron 10 estudiantes pertenecientes a diferentes programas académicos de dicha universidad. La recolección de datos se realizó a través del análisis de los resúmenes producidos por los estudiantes, antes y después de la implementación de la secuencia didáctica, mediante una rejilla elaborada por los investigadores para tal fin; con ella se valoraron tres dimensiones de la producción textual: componente lingüístico, componente comunicativo y el resumen. Los principales referentes teóricos para este trabajo fueron: Teodoro Álvarez, Ana Camps, Jeremy Harmer, Dell Hymes y el Consejo de Europa, los cuales enfatizan la necesidad de tener en cuenta en la enseñanza de la producción escrita, no solo los aspectos lingüísticos, sino también los comunicativos, lo que implica trabajar en el aula con textos auténticos, en situaciones reales de comunicación. Los resultados evidencian que los estudiantes mejoraron en las tres dimensiones, sin embargo los mejores desempeños en el pos-test, se observaron en lo referente al componente lingüístico, específicamente en la ortografía y la concordancia gramatical, y en el componente comunicativo, en lo que respecta a la coherencia y el propósito. Los menores desempeños se evidenciaron en lo concerniente a la sintaxis y a la elaboración de la fase de conclusión del resumen. Asimismo los hallazgos permiten afirmar que la implementación de secuencias didácticas puede contribuir en el mejoramiento de la producción escrita de los estudiantes, lo que conlleva a reflexionar acerca de la necesidad de replantear aquellas prácticas en las que se enseña la escritura a partir de actividades intuitivas y basadas únicamente en la enseñanza de la estructura de la lengua