On the Lagrange and Markov Dynamical Spectra for Geodesic Flows in Surfaces with Negative Curvature

We consider the Lagrange and the Markov dynamical spectra associated to a geodesic flow on a surface of negative curvature. We show that for a large set of real functions on the unit tangent bundle and for typical metrics with negative curvature and finite volume, both the Lagrange and the Markov dynamical spectra have non-empty interior

Skype™ conference calls for foreign languages: call me on Skype™ whenever you want to practice your target language

117 Páginas.Este trabajo presenta los resultados de una investigación sobre la enseñanza y el aprendizaje de Inglés, utilizando herramientas de comunicación mediadas a través del computador, particularmente las llamadas de conferencia de Skype™. Este estudio se realizó con un grupo de 12 estudiantes adultos de inglés como lengua extranjera con un nivel lingüístico de A1 de acuerdo al Marco Común Europeo de Referencia en el instituto de lenguas (ILUD) de una universidad estatal en Bogotá, Colombia. Los principales resultados mostraron que las llamadas de conferencia de Skype™ pueden ser consideradas como una herramienta de influencia para promover la habilidad de habla de estudiantes adultos de inglés como lengua extranjera, especialmente con fines de interacción social y el refuerzo oral de tanto los contenidos de clase como la fluidez en el lenguaje fuera de los salones de clase. / This paper presents the results of a research study into the teaching and learning of English through the use of Computer-Mediated Communication tools, particularly Skype™ conference calls. This study was carried out with a group of 12 EFL A1 adult learners in the language institute (ILUD) of a state university in Bogotá, Colombia. The main findings of this study involve the fact that Skype™ conference calls might be considered as an influential CMC tool to promote EFL adult A1 learners’ speaking skill, especially for social interaction purposes and oral reinforcement of both language fluency and course contents out of classroom settings

Productivity provides the key to Peru's bid for OECD membership

Only by investing in innovation, reducing business informality, and producing clearer statistical data will Peru be able to boost its poor productivity and step up to OECD membership, writes Alonso Morán de Romaña (Ministry of Production, Peru)

Riemannian manifolds with Anosov geodesic flow do not have conjugate points

{In this paper}, we prove that any non-compact complete Riemannian manifold with lower curvature bound and geodesic flow of Anosov type does not have conjugate points. In particular, we answer an open problem mentioned in \cite{Knieper} that is related to Man\'e's statements in \cite{man:87} about a generalization of the Klingenberg's theorem to non-compact manifolds

Geometric conditions to obtain Anosov geodesic flow in non-compact manifolds

Let $(M, g)$ be a complete Riemannian manifold without focal points and curvature bounded below. We prove that when the average of the sectional curvature in tangent planes along geodesics is negative and uniformly away from zero, then the geodesic flow is of Anosov type. We use this result to construct a non-compact manifold of non-positive curvature with the geodesic flow of Anosov type