Internal tide generation by tall ocean ridges

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2009Internal tides are internal waves of tidal period generated by tidal currents flowing over submarine topography. Tall ridges that are nominally two-dimensional (2-D) are sites of particularly strong generation. The subsequent dissipation of internal tides contributes to ocean mixing, thereby playing an important role in the circulation of the ocean. Strong internal tides can also evolve into internal wave solitons, which affect acoustic communication, offshore structures and submarine navigation. This thesis addresses the generation of internal tides by tall submarine ridges using a combined analytical and experimental approach. The first part of the thesis is an experimental investigation of a pre-existing Green function formulation for internal tide generation by a tall symmetric ridge in a uniform density stratification. A modal decomposition technique was developed to characterize the structure of the experimental wave fields generated by 2D model topographies in a specially configured wave tank. The theory accurately predicts the low mode structure of internal tides, and reasonably predicts the conversion rate of internal tides infinite tidal excursion regimes, for which the emergence of non-linearities was notable in the laboratory. In the second part of the thesis, the Green function method is advanced for asymmetric and multiple ridges in weakly non-uniform stratifications akin to realistic ocean situations. A preliminary investigation in uniform stratification with canonical asymmetric and double ridges reveals asymmetry in the internal tide that can be very sensitive to the geometric configuration. This approach is then used with realistic topography and stratification data to predict the internal tide generated by the ridges at Hawaii and at the Luzon Strait. Despite the assumption of two-dimensionality, there is remarkably good agreement between field data, simulations and the new theory for the magnitude, asymmetry and modal content of the internal tide at these sites. The final part of the thesis investigates the possibility of internal wave attractors in the valley of double-ridge configurations. A one-dimensional map is developed to identify the existence and stability of attractors as a function of the ridge geometry. The Green function method is further advanced to include a viscous correction to balance energy focusing and dissipation along an attracting orbit of internal wave rays, and very good agreement is obtained between experiment and theory, even in the presence of an attractor.My Ph. D. and the work in this thesis have been generously funded by the National Science Foundation under grants OCE 0645529 and OCE 04-25283 and the Office of Naval Research under grants N00014-08-0390, N00014-05-1-0573 and N00014-09-0282

Critical Pedagogy and L2 Education in the Global South

ABSTRACT: Colombia, as other Latin American countries, has not been indifferent to the power of English as the language of business, international communication and academia. Since the end of the 20th century, there has been a great push in the country to promote the teaching of English: language policies have been formulated, ideal levels of proficiency have been established (based on a framework initially designed for European countries), and a national English curriculum for all grade levels has been distributed among schools. The status English has gained competes with that of other foreign languages and more evidently with heritage languages. The field of L2 education in Colombia is experiencing a tension between neoliberal interests of L2 education to support social mobility and the nation’s economic growth and political power (with a focus on linguistic and communicative competence), and alternative academic agendas grounded on the analysis of the influence of social, cultural, and economic factors on L2 teaching and learning, and on learners’ identities. In this article, I use the example of an analysis of L2 education, from a critical pedagogy standpoint, using a Latin American university as a context to depict such a contrast. This University is a place where there is confluence of diverse languages that have different social statuses: English as lingua franca, European and Asian foreign languages, and heritage languages. I argue that critical pedagogy, partly inspired in the work from intellectuals from the Hemispheric South, serves as a framework to guide analyses of power in the relationship between these languages and L1, and the effect of such relations of power on learners’ identities. Also, I contend that by using critical pedagogy in this context, it becomes transformed, nurtured, as it overlaps and dialogues with other knowledges developed in the Hemispheric South

Dándole sentido a la pedagogía crítica en la educación en L2 a través de un grupo de estudio colaborativo

RESUMEN: Presentamos nuestras experiencias del proceso de comprender la pedagogía crítica por parte de un grupo de profesores de inglés, que fue creado con el propósito de aprender cómo se puede enseñar la lengua desde una perspectiva crítica, en diferentes contextos en Medellín. Nos enfocamos particularmente en los desafíos que implica construir significado sobre la pedagogía crítica cuando no todas las integrantes podían acceder a este discurso de la misma manera. Para ilustrar nuestro proceso de comprensión individual y grupal de la teoría, utilizamos las narrativas de algunas integrantes del grupo como ejemplos de nuestras diversas perspectivas. Planteamos que darle sentido a la pedagogía crítica como parte de un proceso de desarrollo profesional implica espacios y situaciones de confrontación personal con la teoría, así como apoyo en el aprendizaje colaborativo a través del diálogo.ABSTRACT: In this article we discuss our experiences in the process of understanding critical pedagogy within an English teachers’ study group which was created for the purpose of learning how to teach language from a critical perspective. We particularly focus on the challenges of meaning making around critical pedagogy, as we realized that we were not all able to similarly enter this discourse. To illustrate our processes of understanding theory individually and collectively, some of the group members’ narratives are used as examples of our different perspectives. We argue that making sense of critical pedagogy, as part of a process of professional development, implies spaces and situations of personal confrontation with theory and support in collaborative learning through dialogue

Mejorar los procedimientos de control interno para el área de nómina del Centro Médico Imbanaco de Cali S.A.

Dentro de las compañías existe una gran necesidad de contar con adecuados sistemas de control interno e información financiera para una efectiva toma de decisiones y así poder salvaguardar los recursos y verificar la eficiencia de las operaciones. Para lograr este objetivo deben implementar mejoras que permitan llevar a cabo dicho objetivo. El control interno es una función de control, de consulta y de gestión con la misión de vigilar y mantener un adecuado sistema de control interno y prevenir futuros riesgos. Como consecuencia del constante desarrollo que tiene el Centro Médico Imbanaco de Cali, requiere para su área de nómina que se mejoren procedimientos de control interno, con el fin de mitigar los riesgos y reducir los posibles fraudes, asegurándose de aplicar de manera correcta las normas contables y evaluación en la eficacia en otros controles. Para llevar a cabo este proyecto y lograr mejorar los procedimientos de control interno en el área de nómina, se realizaron distintas exploraciones, inicialmente académicas con las cuales se busca conocer que tanto se ha estudiado sobre el tema de interés, de igual forma se investiga la empresa para la que se quiere mejorar los controles, obteniendo tanto información verbal por medio de entrevistas a empleados del área, como información documentada que apoye y respalde estas entrevistas

Caracterización de un AGV (vehículo guiado automáticamente) en el sistema de manufactura flexible, caso Centro Tecnológico de Automatización CTAI de la Pontificia Universidad Javeriana

Ingeniero (a) IndustrialPregrad

Experimental investigation of internal tide generation by two-dimensional topography using synthetic Schlieren

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 78-81).An experimental investigation of internal tide generation at two-dimensional topography was carried out using the synthetic Schlieren experimental technique. Two linear models were tested: Balmforth, Ierley and Young's [1] subcritical solution for a Gaussian ridge and Hurley and Keady's [15] super-critical solution for a knife-edge. The former was modified to account for the effects of viscosity in the propagating wave beams. The experiment set up comprised a wave-tank with a linear salt-water stratification and a sliding stage on which the topography oscillated horizontally to simulate tidal flow. The wave field was measured by capturing the distortion of a pattern of random dots placed on a light sheet behind the tank using a CCD camera, and using the synthetic Schlieren processing of the movies obtained. Four experiments were performed, for wave beams propagating close to 25 ° and 56 from the horizontal for each topographic feature. The subcritical theory over-predicted the peak disturbance over the Gaussian ridge by a maximum of 50%, and it correctly predicted the profile shape and evolution along the wave beam and throughout one period of the oscillation.(cont.) The supercritical knife-edge theory predicted the disturbance amplitude, shape and evolution within experimental error. The results showed that at Reynolds numbers below 0(105), viscosity suppresses nonlinear effects and smoothes out instabilities predicted by inviscid models that would lead to overturning. These experiments have motivated the construction of a larger wave-tank to achieve higher Reynolds numbers. Future experiments will investigate nonlinear internal tide generation, overturning and mixing in unstable wave beams and flow separation over topography.by Paula Echeverri Mondragón.S.M

La implementación de un currículo de inglés basado en estándares : el caso de las Instituciones Educativas Públicas de Medellín

ABSTRACT: This case study explored Medellín's secondary English teachers' perspectives, practices, and experiences related to English curriculum design and implementation in public schools. Data were collected using a survey sent to all secondary schools' English teachers, analysis of school curriculum documents, and focus group interviews at five purposefully selected schools. Data indicate that there is a gap between the teachers' preconceived notions of curriculum as holistic and integrative, and the notion of curriculum implied in the curriculum development process they implement (a more technical one). This gap is also evident in the schools' general curriculum documents (that state the institution's educational, holistic goals), and the English syllabus, (that tend to focus on language structures or communicative functions). Data also revealed the many challenges teachers face when designing and implementing the curriculum, including lack of preparation on curriculum development, collaborative work among teachers, and time to develop the contents. In conclusion, English teachers in public secondary schools need more significant and sustainable support in the analysis of contexts, as well as in the adaptation of curriculum guidelines.RESUMEN: Este estudio de caso exploró las ideas, prácticas y experiencias de los maestros de inglés de secundaria, de la ciudad de Medellín, en relación con el diseño y la implementación del currículo de inglés en las instituciones educativas públicas. Los datos se recolectaron a través de una encuesta enviada a los profesores de inglés de los colegios de secundaria, del análisis de los documentos curriculares de los colegios y grupos focales en cinco instituciones seleccionadas con propósitos específicos. Los datos indican que hay una brecha entre las nociones de currículo en las que creen los maestros, más integrales e integradoras, y la noción de currículo que está implícita en el proceso de desarrollo curricular que ellos implementan (una visión más técnica del currículo). Esta brecha también es evidente en los documentos curriculares de los colegios (que establecen los objetivos educativos) y los programas de curso de inglés (que tienden a enfocarse en estructuras lingüísticas y funciones comunicativas). Los datos también muestran que los maestros enfrentan muchos desafíos en el diseño e implementación del currículo, incluyendo la falta de preparación en desarrollo curricular, falta de trabajo colaborativo entre los maestros y falta de tiempo para desarrollar los contenidos. En conclusión, los maestros de inglés de las instituciones públicas de secundaria necesitan un apoyo más significativo y sostenible en el análisis de los contextos, así como para la adaptación de las pautas curriculares

A implementação de um currículo baseado em inglês com base nos padrões: o caso das instituições educacionais públicas de Medellín

This case study explored Medellín’s secondary English teachers’ perspectives, practices, and experiences related to English curriculum design and implementation in public schools. Data were collected using a survey sent to all secondary schools’ English teachers, analysis of school curriculum documents, and focus group interviews at five purposefully selected schools. Data indicate that there is a gap between the teachers’ preconceived notions of curriculum as holistic and integrative, and the notion of curriculum implied in the curriculum development process they implement (a more technical one). This gap is also evident in the schools’ general curriculum documents (that state the institution’s educational, holistic goals), and the English syllabus, (that tend to focus on language structures or communicative functions). Data also revealed the many challenges teachers face when designing and implementing the curriculum, including lack of preparation on curriculum development, collaborative work among teachers, and time to develop the contents. In conclusion, English teachers in public secondary schools need more significant and sustainable support in the analysis of contexts, as well as in the adaptation of curriculum guidelines.Este estudio de caso exploró las ideas, prácticas y experiencias de los maestros de inglés de secundaria, de la ciudad de Medellín, en relación con el diseño y la implementación del currículo de inglés en las instituciones educativas públicas. Los datos se recolectaron a través de una encuesta enviada a los profesores de inglés de los colegios de secundaria, del análisis de los documentos curriculares de los colegios y grupos focales en cinco instituciones seleccionadas con propósitos específicos. Los datos indican que hay una brecha entre las nociones de currículo en las que creen los maestros, más integrales e integradoras, y la noción de currículo que está implícita en el proceso de desarrollo curricular que ellos implementan (una visión más técnica del currículo). Esta brecha también es evidente en los documentos curriculares de los colegios (que establecen los objetivos educativos) y los programas de curso de inglés (que tienden a enfocarse en estructuras lingüísticas y funciones comunicativas). Los datos también muestran que los maestros enfrentan muchos desafíos en el diseño e implementación del currículo, incluyendo la falta de preparación en desarrollo curricular, falta de trabajo colaborativo entre los maestros y falta de tiempo para desarrollar los contenidos. En conclusión, los maestros de inglés de las instituciones públicas de secundaria necesitan un apoyo más significativo y sostenible en el análisis de los contextos, así como para la adaptación de las pautas curriculares.Este estudo de caso explorou as idéias, práticas e experiências de professores de inglês do ensino médio na cidade de Medellín, em relação ao desenho e implementação do currículo de inglês em instituições públicas educacionais. Foram utilizados vários métodos de pesquisa que incluíram levantamento, análise de documentos curriculares das escolas e grupos focais em seis instituições selecionadas para fins específicos. Os dados indicam que existe uma lacuna entre as noções de currículo em que acreditam os professores, mais abrangentes e inclusivas, e a noção de currículo que está implícita no processo de desenvolvimento curricular que eles implementam, o que é uma visão mais técnica do currículo. Essa lacuna também é evidente nos documentos curriculares das escolas, onde são estabelecidos objetivos educacionais e programas de cursos de inglês, que tendem a se concentrar em estruturas linguísticas e funções comunicativas. Os dados também mostram que os professores enfrentam muitos desafios na concepção e implementação do currículo, incluindo falta de preparação no desenvolvimento do currículo, falta de trabalho colaborativo entre os professores, falta de tempo para desenvolver conteúdo, entre outros. Em relação aos documentos sobre padrões de suficiência e currículo emitidos pelos governos nacionais e locais, os professores consideram que, embora sejam claros e coerentes, não correspondem ao contexto e às condições que enfrentam em sua prática cotidiana

Parent Engagement and Cultural Capital: Negotiating Culture in a Multilingual/Multiethnic School

This study explored how a multicultural/multilingual school negotiated culture with limited English proficient (LEP) students\u27 families, particularly in the context of parent involvement activities. In order to understand how such negotiation of culture occurred, the researcher focused on the perspectives that school administrators, teachers and parents of students in an English as a Second Language (ESL) program had on the education of LEP students and their parents\u27 involvement in school-organized activities. It also focused on the participants\u27 understandings of cultural capital and the extent to which the school builds on immigrant /sojourner families\u27 knowledge and culture to support their children\u27s education. In this ethnographical study, the researcher used a variety of data collection procedures: a questionnaire for teachers and parents, document analysis, interviews, and participant observation. While results from the questionnaires show that teachers and parents had similar views of LEP student education and parent involvement, more detailed information gathered through interviews and observations show that school personnel and immigrant/sojourner parents held different perspectives and expectations. Moreover, the results revealed that cultural capital, social class, and parents\u27 educational attainment level influence the way parents understand the academic and social expectations of the school\u27s dominant culture and their interactions with school personnel. Likewise, cultural biases influence school administrators and teachers\u27 perceptions and interactions with parents from ethnic/linguistic minority groups

Poesía e ilustración en El corazón del árbol de Piedad Bonnet

Poesía e ilustración, una combinación mágica para presentar un asombroso y animado mundo literario, no sólo para los más pequeños en edad, sino también para los grandes que nos dejamos abrazar por estas piezas artísticas. El corazón del árbol, es una invita-ción a darle sentido en nuestra mente a las palabras de la ya reconocida escritora Piedad Bonnett, de la mano del ilustrador Daniel Gómez Henao, quien nos armoniza estas palabras por medio de las formas y los colores