Limit cycles for cubic systems with a symmetry of order 4 and without in nite critical points

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On the upper bound of the number of limit cycles obtained by the second order averaging method I

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On the upper bound of the number of limit cycles obtained by the second order averaging method II

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The third order Melnikov function of a quadratic center under quadratic perturbation

We study quadratic perturbations of the integrable system (1+x)dH; where H =(x²+y²)=2: We prove that the first three Melnikov functions associated to the perturbed system give rise at most to three limit cycles.

Dynamics of the third order Lyness' difference equation

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Manual del curso básico: la accesibilidad en el servicio público

El manual del curso está estructurado en ocho capítulos. Los seis primeros desarrollan los contenidos necesarios para conocer y aplicar las condiciones de accesibilidad adecuadamente en los servicios públicos: desde las nociones y características vinculadas con las necesidades de distintos tipos de ciudadanos, hasta el contexto normativo, institucional y conceptual que se ha venido consolidando en torno a la idea de accesibilidad universal. Los dos últimos capítulos ofrecen medidas y recomendaciones para lograr una administración pública accesible, tanto en sus servicios donde se produce la relación con los ciudadanos, como en los entornos en que los empleados trabajan.

Clean Development Mechanism and Sustainable Development: a discussion on the link between the CDM and Sustainable Development, an analysis of the current status of the CDM portfolio, and an multicriteria evaluation of the effects of additional incentives in order to foster broad local Sustainable Development dividends from the CDM projects

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Iniciativas para el desarrollo sostenible del Área de Conservación Arenal- Huetar Norte, Costa Rica

El presente proyecto tiene como zona de estudio el Área de Conservación Arenal- Huetar Norte (ACA-HN), concretamente los cantones de Upala, Los Chiles y Guatuso. El propósito del proyecto es promover el desarrollo sostenible de la zona mediante los pilares de la educación y la economía. Para ello se elabora un manual de educación ambiental de la cuenca de río Frío y así poder solventar algunas de las carencias en educación que tienen los docentes de las escuelas de la cuenca hidrográfica. Por otro lado, se diagnostica la cadena de valor sobre usos alternativos de la biodiversidad, específicamente zoocriaderos de mariposas diurnas, en los cantones de Upala y Los Chiles. Por último, se trata la información de la zona de estudio con Sistemas de Información Geográfica (SIG) para elaborar mapas que ilustren los proyectos anteriores y el proyecto sobre el diagnóstico de la industria de turismo local.

A public-key cryptosystem based on second order linear sequences

Based on Lucas functions, an improved version of the Diffie-Hellman distribution key scheme and to the ElGamal public key cryptosystem scheme are proposed, together with an implementation and computational cost. The security relies on the difficulty of factoring an RSA integer and on the difficulty of computing the discrete logarithm.

Representation of motor habit in a sequence of repetitive reach and grasp movements performed by macaque monkeys: evidence for a contribution of the dorsolateral prefrontal cortex.

In the context of an autologous cell transplantation study, a unilateral biopsy of cortical tissue was surgically performed from the right dorsolateral prefrontal cortex (dlPFC) in two intact adult macaque monkeys (dlPFC lesioned group), together with the implantation of a chronic chamber providing access to the left motor cortex. Three other monkeys were subjected to the same chronic chamber implantation, but without dlPFC biopsy (control group). All monkeys were initially trained to perform sequential manual dexterity tasks, requiring precision grip. The motor performance and the prehension's sequence (temporal order to grasp pellets from different spatial locations) were analysed for each hand. Following the surgery, transient and moderate deficits of manual dexterity per se occurred in both groups, indicating that they were not due to the dlPFC lesion (most likely related to the recording chamber implantation and/or general anaesthesia/medication). In contrast, changes of motor habit were observed for the sequential order of grasping in the two monkeys with dlPFC lesion only. The changes were more prominent in the monkey subjected to the largest lesion, supporting the notion of a specific effect of the dlPFC lesion on the motor habit of the monkeys. These observations are reminiscent of previous studies using conditional tasks with delay that have proposed a specialization of the dlPFC for visuo-spatial working memory, except that this is in a different context of "free-will", non-conditional manual dexterity task, without a component of working memory.

Manual de preparació per a olimpíades i competicions matemàtiques

Treball de recerca realitzat per un alumne d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2008. Es presenta als interessats en les competicions de matemàtiques un manual sòlid, compacte, però sintetitzat, que els permeti, complementar i ampliar els seus coneixements matemàtics dirigits a aquestes competicions. En la primera part, es tracten les olimpíades matemàtiques més importants estatals i arreu del món per tal de donar-les a conèixer al lector. A continuació s'expliquen les tècniques generals més utilitzades per construir una demostració determinada. Finalment, es tanca la secció parlant de la creació de problemes, un apartat que permet estimular i potenciar la pròpia creativitat. En la segona part, es troba el propi cos del manual, amb una gran quantitat de problemas solucionats. Per tal de facilitar-ne l'ús, s'ha dividit en quatre grans temes, corresponents als que es treballen a les Olimpíades Matemàtiques: teoria de nombres o aritmètica, geometria, àlgebra i combinatòria. Cada un d'aquests temes es troba, a la vegada, dividit en dues seccions: la de teoremes i conceptes, en què s'enuncien els principals teoremes i fórmules que el lector necessita conéixer, i la d'exercicis i problemes on s’han recollit multitud de problemes provinents de diferents competicions, indicant el grau de dificultat - cal remarcar però, que el present document és una reducció del treball original, per això s'ha decidit només incloure-hi l'apartat d'aritmètica i ometre els altres tres -.

An investigation of customer order flow in the foreign exchange market

This paper examines the effect that heterogeneous customer orders flows have on exchange rates by using a new, and the largest, proprietary dataset of weekly net order flow segmented by customer type across nine of the most liquid currency pairs. We make several contributions. Firstly, we investigate the extent to which customer order flow can help to explain exchange rate movements over and above the influence of macroeconomic variables. Secondly, we address the issue of whether order flows contain (private) information which explain exchange rates changes. Thirdly, we look at the usefulness of order flow in forecasting exchange rate movements at longer horizons than those generally considered in the microstructure literature. Finally we address the question of whether the out-of-sample exchange rate forecasts generated by order flows can be employed profitably in the foreign exchange markets

Second-Order Approximation to the Rotemberg Model around a Distorted Steady State

Less is known about social welfare objectives when it is costly to change prices, as in Rotemberg (1982), compared with Calvo-type models. We derive a quadratic approximate welfare function around a distorted steady state for the costly price adjustment model. We highlight the similarities and differences to the Calvo setup. Both models imply inflation and output stabilization goals. It is explained why the degree of distortion in the economy influences inflation aversion in the Rotemberg framework in a way that differs from the Calvo setup.

Empresa Davantis: seguimiento de personas y vehículos por videovigilancia inteligente

Este proyecto, desarrollado en la empresa Davantis, tiene como objetivo encontrar posibles mejoras a su actual sistema de videovigilancia, el Daview. El proyecto está dedicado al estudio del algoritmo de seguimiento Mean Shift para la elaboración de un sistema de tracking. Para ello se han desarrollado y evaluado tres implementaciones diferentes, mediante las cuales se han encontrado mejoras que complementan al módulo de tracking del Daview. También se ha estudiado la utilidad de un sistema de evaluación manual frente a uno de automático.

Microstructure Order Flow: Statistical and Economic Evaluation of Nonlinear Forecasts

In this paper we propose a novel empirical extension of the standard market microstructure order flow model. The main idea is that heterogeneity of beliefs in the foreign exchange market can cause model instability and such instability has not been fully accounted for in the existing empirical literature. We investigate this issue using two di¤erent data sets and focusing on out- of-sample forecasts. Forecasting power is measured using standard statistical tests and, additionally, using an alternative approach based on measuring the economic value of forecasts after building a portfolio of assets. We nd there is a substantial economic value on conditioning on the proposed models.