Now showing items 1-20 of 26

    • A pseudo-normal form for planar vector fields 

      Delshams Valdés, Amadeu; Guillamon Grabolosa, Antoni; Lázaro Ochoa, José Tomás (2001)
      Article
      Open Access
    • Abundance of attracting, repelling and elliptic periodic orbits in two-dimensional reversible maps 

      Delshams Valdés, Amadeu; Gonchenko, S.V.; Lázaro Ochoa, José Tomás; Stenkin, Oleg (2013-01-01)
      Article
      Open Access
      We study dynamics and bifurcations of two-dimensional reversible maps having non-transversal heteroclinic cycles containing symmetric saddle fixed points. We consider one-parameter families of reversible maps unfolding ...
    • Abundance of attracting, repelling and elliptic periodic orbits in two-dimensional reversible maps 

      Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás; Gonchenko, S.V.; Sten'kin, Oleg (2012-01-12)
      External research report
      Open Access
      Abstract. We study dynamics and bifurcations of two-dimensional reversible maps having non-transversal heteroclinic cycles containing symmetric saddle periodic points. We consider one-parameter families of reversible ...
    • Breathers in a model of a polymer with secondary structure 

      Kastner, Michael; Lázaro Ochoa, José Tomás (2002)
      Article
      Open Access
    • Càlcul numèric : manual de pràctiques 

      Lázaro Ochoa, José Tomás; Ollé Torner, Mercè; Pacha Andújar, Juan Ramón (Universitat Politècnica de Catalunya, 2014)
      Practice
      Open Access
    • Càlcul numèric. Manual de pràctiques 

      Lázaro Ochoa, José Tomás; Ollé Torner, Mercè; Pacha Andújar, Juan Ramón (2014-07)
      External research report
      Open Access
    • Differential galois theory and non-integrability of planar polynomial vector fields 

      Lázaro Ochoa, José Tomás; Pantazi, Chara; Acosta Humanez, Primitivo; Morales Ruiz, Juan José (2018-02-26)
      Article
      Restricted access - publisher's policy
      We study a necessary condition for the integrability of the polynomials vector fields in the plane by means of the differential Galois Theory. More concretely, by means of the variational equations around a particular ...
    • Dynamics and bifurcations in a simple quasispecies model of tumorigenesis 

      Castillo, Vanessa; Lázaro Ochoa, José Tomás; Sardañés, Josep (2015-05-18)
      Article
      Open Access
      Cancer is a complex disease and thus is complicated to model. However, simple models that describe the main processes involved in tumoral dynamics, e.g., competition and mutation, can give us clues about cancer behavior, ...
    • Dynamics in a time-discrete food-chain model with strong pressure on preys 

      Lázaro Ochoa, José Tomás; Alsedà, Lluís; Vidiella, Blai; Solé Vicente, Ricard; Sardañés, Josep (2020-05-01)
      Article
      Restricted access - publisher's policy
      Discrete-time dynamics, mainly arising in boreal and temperate ecosystems for species with non-overlapping generations, have been largely studied to understand the dynamical outcomes due to changes in relevant ecological ...
    • Effective stability in reversible systems 

      Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás (1997)
      Article
      Open Access
      In this paper we present a procedure to put in normal form a nearly-integrable reversible system, not necessarily a Hamiltonian system. Furthermore, non-resonant stability estimates are obtained. As an application we discuss ...
    • Full analysis of small hypercycles with shortcircuits in prebiotic evolution 

      Lázaro Ochoa, José Tomás; Guillamon Grabolosa, Antoni; Fontich, Ernest; Sardañés, Josep (2017-01-05)
      Article
      Restricted access - publisher's policy
      It is known that hypercycles are sensitive to the so-called parasites and short-circuits. While the impact of parasites has been widely investigated for well-mixed and spatial hypercycles, the effect of short-circuits in ...
    • Mixed dynamics in reversible maps with gure-8 homoclinic connections 

      Delshams Valdés, Amadeu; Gonchenko, Sergey; Lázaro Ochoa, José Tomás (2014)
      Conference report
      Open Access
      We study dynamics and bifurcations of two-dimensional reversible maps having non-transversal heteroclinic cycles containing symmetric saddle periodic points. We consider one-parameter families of rev ersible maps unfolding ...
    • Mixed dynamics of two-dimensional reversible maps with a symmetric couple of quadratic homoclinic tangencies 

      Lázaro Ochoa, José Tomás; Delshams Valdés, Amadeu; Gonchenko, Marina; Gonchenko, Sergey (American Institute of Mathematical Sciences, 2018-09)
      Article
      Open Access
      We study dynamics and bifurcations of 2-dimensional reversible maps having a symmetric saddle fixed point with an asymmetric pair of nontransversal homoclinic orbits (a symmetric nontransversal homoclinic figure-8). We ...
    • On dynamics and invariant sets in predator-prey maps 

      Lázaro Ochoa, José Tomás; Alsedà, Lluís; Sardañés, Josep; Vidiella, Blai (2019-11-27)
      Part of book or chapter of book
      Open Access
      A multitude of physical, chemical, or biological systems evolving in discrete time can be modelled and studied using difference equations (or iterative maps). Here we discuss local and global dynamics for a predator-prey ...
    • On Normal Forms and Splitting of Separatrices in Reversible Systems 

      Lázaro Ochoa, José Tomás (Universitat Politècnica de Catalunya, 2003-10-23)
      Doctoral thesis
      Open Access
      És difícil dibuixar una frontera, dins la Teoria de Sistemas Dinàmics, entre lleis de conservació i simetries doncs, sovint, les seves característiques es confonen. Un clar exemple d'aquest fenómen el constitueixen els ...
    • On the Chebyshev property for a new family of functions 

      Lázaro Ochoa, José Tomás; Gasull Embid, Armengol; Torregrosa, Joan (2012-03)
      Article
      Open Access
    • On the integrability of polynomial fields in the plane by means of Picard-Vessiot theory 

      Lázaro Ochoa, José Tomás; Morales Ruíz, Juan José; Acosta Humánez, Primitivo Belén; Pantazi, Chara (2012-01-12)
      External research report
      Open Access
      We study the integrability of polynomial vector fields using Galois theory of linear differential equations when the associated foliations is reduced to a Riccati type foliation. In particular we obtain integrability results ...
    • On the integrability of polynomial vector fields in the plane by means of Picard-Vessiot theory 

      Acosta-Humànez, Primitivo; Lázaro Ochoa, José Tomás; Morales Ruiz, Juan José; Pantazi, Chara (American Institute of Mathematical Sciences, 2015-05-01)
      Article
      Open Access
      We study the integrability of polynomial vector fields using Galois theory of linear differential equations when the associated foliations is reduced to a Riccati type foliation. In particular we obtain integrability results ...
    • Pseudo-normal form near saddle-center or saddle-focus equilibria 

      Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás (2003)
      Article
      Open Access
      In this paper we introduce the pseudo-normal form, which generalizes the notion of normal form around an equilibrium. Its convergence is proved for a general analytic system in a neighborhood of a saddle-center or a ...
    • Pseudo-normal forms and their applications 

      Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás (2001)
      Article
      Open Access