A New Nonlinear Liquid Drop Model. Clusters as Solitons on The Nuclear Surface

By introducing in the hydrodynamic model, i.e. in the hydrodynamic equations and the corresponding boundary conditions, the higher order terms in the deviation of the shape, we obtain in the second order the Korteweg de Vries equation (KdV). The same equation is obtained by introducing in the liquid drop model (LDM), i.e. in the kinetic, surface and Coulomb terms, the higher terms in the second order. The KdV equation has the cnoidal waves as steady-state solutions. These waves could describe the small anharmonic vibrations of spherical nuclei up to the solitary waves. The solitons could describe the preformation of clusters on the nuclear surface. We apply this nonlinear liquid drop model to the alpha formation in heavy nuclei. We find an additional minimum in the total energy of such systems, corresponding to the solitons as clusters on the nuclear surface. By introducing the shell effects we choose this minimum to be degenerated with the ground state. The spectroscopic factor is given by the ratio of the square amplitudes in the two minima.Comment: 27 pages, LateX, 8 figures, Submitted J. Phys. G: Nucl. Part. Phys., PACS: 23.60.+e, 21.60.Gx, 24.30.-v, 25.70.e

Procesos de negociación de significado en una escuela normal mexicana Processes of negotiation of meaning in a mexican program of teacher education

En este trabajo, analizamos algunos procesos de negociación de significado y desarrollo de micropolíticas en las experiencias de docentes y directivos en una escuela normal mexicana con la reforma a la educación normal de 1997. En dicho plan de estudios se estipula que los estudiantes realicen prácticas escolares durante el último año de la carrera. El estudio se enfocó en las actividades que realizaron los docentes de manera previa a las prácticas del preservicio con la primera generación de estudiantes del plan de 1997 de la Licenciatura en Educación Primaria. En el artículo mostramos cómo los docentes y el personal directivo de la normal del estudio, transitaron por un proceso de negociación de significado y generación de micropolíticas en su relación con la propuesta curricular nacional y la forma en que se organizaron bajo un esquema que concebimos como comunidad de práctica cultivada.<br>Neste trabalho analisamos alguns processos de negociação de significado e desenvolvimento de micro-políticas nas experiências dos docentes e autoridades em uma escola normal mexicana após a reforma à educação normal de 1997. Neste programa de estudos estipula-se que os estudantes realizem os estágios escolares durante o último ano da faculdade. O estudo foi focado nas atividades que realizaram os docentes de forma prévia aos estágios do pré-serviço com a primeira geração de estudantes do plano de 1997 do Bacharelado em Educação Primária (Ensino Básico). No artigo mostramos como os docentes e autoridades da normal do estudo, transitaram por um processo de negociação de significado e geração de micro-política na sua realização com a proposta curricular nacional e a maneira com a qual foram organizados, sob um esquema que concebemos como comunidade de prática cultivada.<br>In this paper, we analyze the experiences of teachers and principals in a Mexican teachers' college following the teacher education reform of 1997. In the aforementioned study program, it is stipulated that students undertake practice in schools during the final year of their degree course. The study focuses on the activities carried out by teachers prior to the pre-service practice with the first generation of students from the 1997 Primary Education degree program. In the paper, we show how the teachers and administrative staff at the teachers' college have adapted by means of a process of negotiation of meaning and the generation of micropolitics in their relationship with the national proposal, and the way in which they are organized as part of a scheme that we conceive as community of practice cultivated