Rotation numbers for planar attractors of equivariant homeomorphisms

Given an integer m>1 we consider Zm-equivariant and orientation preserving homeomorphisms in the plane with an asymptotically stable fixed point at the origin. We present examples without periodic points and having some complicated dynamical features. The key is a preliminary construction of Zm-equivariant Denjoy maps of the circle

The Discrete Markus-Yamabe Problem for Symmetric Planar Polynomial Maps

We probe deeper into the Discrete Markus-Yamabe Question for polynomial planar maps and into the normal form for those maps which answer this question in the affirmative. Furthermore, in a symmetric context, we show that the only nonlinear equivariant polynomial maps providing an affirmative answer to the Discrete Markus-Yamabe Question are those possessing Z2 as their group of symmetries. We use this to establish two new tools which give information about the spectrum of a planar polynomial map

Global Saddles for Planar Maps

We study the dynamics of planar diffeomorphisms having a unique fixed point that is a hyperbolic local saddle. We obtain sufficient conditions under which the fixed point is a global saddle. We also address the special case of $D_2$-symmetric maps, for which we obtain a similar result for $C^1$ homeomorphisms. Some applications to differential equations are also given

Quiescence: a mechanism for escaping the effects of drug on cell populations

We point out that a simple and generic strategy to lower the risk for extinction consists in the developing a dormant stage in which the organism is unable to multiply but may die. The dormant organism is protected against the poisonous environment. The result is to increase the survival probability of the entire population by introducing a type of zero reproductive fitness. This is possible, because the reservoir of dormant individuals act as a buffer that can cushion fatal fluctuations in the number of births and deaths which without the dormant population would have driven the entire population to extinction.Comment: 18 pages and 9 figure

Trabajos escritos

Tercera unidad de la serie “Administración empresarial básica. Metodología” en la que se describen conceptos y fundamentos para la elaboración de informes y trabajos escritos.Third unit of the series “Basic business administration. Methodology ”in which concepts and foundations for the preparation of reports and written works are described.Utilización del lenguaje -- Formas gramaticales -- Estructuras sintácticas -- Ortografía -- Definición -- Principales reglas ortográficas -- Elaboración de trabajos escritos -- Redacción de párrafos -- Redacción de documentos -- Elaboración de tablas, figuras y notas -- Elaboración de citas -- Elaboración de referenciasna110 página

Electronic Design of a DC-DC Boost Converter for Powering a Lo-Ra Communication Board with Bioelectricity by “Plantas Andinas”

The use of bioelectricity in various areas of science has made it indispensable to resort to new technologies to take full advantage of this natural resource. Plants are living beings, and through their biochemical processes produce a small amount of electricity derived from oxidation-reduction processes. For this reason, it is proposed to use electronic and power techniques to increase the flow of electrons produced by plants of Andean characteristics, and consequently feed a Lo-Ra type communication card, meeting the needs of long-distance data transmission, used in the collection of field information, either in areas where access or availability of power lines is complex. This proposal motivates us to continue working on sustainable energy and the exploitation of natural resources. This document details the theory, practice, and methods used to meet the objective of supplying power to a wireless communication system over a long distance. First, a description of the most important issues to be addressed is developed, and then special focus is given to the design for development of the power electronics circuit, specifically an elevator type DC-DC converter. Finally, the results obtained through the implementation used in this case are documented. Keywords: bioelectricity, MFC, boost-converter, Andean plants, totora, Lo-Ra TTGO. Resumen El uso de bioelectricidad en diversas áreas de la ciencia ha hecho indispensable recurrir a nuevas tecnologías para aprovechar al máximo este recurso natural. Las plantas, como seres vivos, producen una pequeña cantidad de electricidad a través de sus procesos bioquímicos, derivada de procesos de oxidación-reducción. Por esta razón, se propone utilizar técnicas electrónicas y de potencia para aumentar el flujo de electrones producidos por plantas de características andinas, y alimentar así una tarjeta de comunicación de tipo Lo-Ra, satisfaciendo las necesidades de transmisión de datos a larga distancia, utilizadas en la recolección de información de campo, ya sea en áreas donde el acceso o la disponibilidad de líneas eléctricas es compleja Esta propuesta motiva a continuar trabajando en energía sostenible y en la explotación de recursos naturales. Este documento detalla la teoría, práctica y los métodos utilizados para cumplir con el objetivo de suministrar energía a un sistema de comunicación inalámbrico a larga distancia. En primer lugar, se desarrolla una descripción de los temas más importantes a abordar, y luego se presta especial atención al desarrollo del diseño del circuito de electrónica de potencia, específicamente un convertidor DC-DC tipo elevador; y finalmente, se documentan los resultados obtenidos a través de la implementación utilizada en este caso. Palabras Clave: bioelectricidad, CCM, convertidor-elevador, plantas andinas, totora, TTGO Lo-Ra

\pi N scattering in relativistic baryon chiral perturbation theory revisited

We have analyzed pion-nucleon scattering using the manifestly relativistic covariant framework of Infrared Regularization up to {\cal O}(q^3) in the chiral expansion, where q is a generic small momentum. We describe the low-energy phase shifts with a similar quality as previously achieved with Heavy Baryon Chiral Perturbation Theory, \sqrt{s}\lesssim1.14 GeV. New values are provided for the {\cal O}(q^2) and {\cal O}(q^3) low-energy constants, which are compared with previous determinations. This is also the case for the scattering lengths and volumes. Finally, we have unitarized the previous amplitudes and as a result the energy range where data are reproduced increases significantly.Comment: 26 pages, 5 figures, 5 table