Browsing by Author "Lázaro Ochoa, José Tomás"

Abundance of attracting, repelling and elliptic periodic orbits in twodimensional reversible maps
Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás; Gonchenko, S.V.; Sten'kin, Oleg (20120112)
External research report
Open AccessAbstract. We study dynamics and bifurcations of twodimensional reversible maps having nontransversal heteroclinic cycles containing symmetric saddle periodic points. We consider oneparameter families of reversible ... 
Abundance of attracting, repelling and elliptic periodic orbits in twodimensional reversible maps
Delshams Valdés, Amadeu; Gonchenko, S.V.; Lázaro Ochoa, José Tomás; Stenkin, Oleg (20130101)
Article
Open AccessWe study dynamics and bifurcations of twodimensional reversible maps having nontransversal heteroclinic cycles containing symmetric saddle fixed points. We consider oneparameter families of reversible maps unfolding ... 
A pseudonormal form for planar vector fields
Delshams Valdés, Amadeu; Guillamon Grabolosa, Antoni; Lázaro Ochoa, José Tomás (2001)
Article
Open Access 
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 (201407)
External research report
Open Access 
Differential galois theory and nonintegrability of planar polynomial vector fields
Lázaro Ochoa, José Tomás; Pantazi, Chara; Acosta Humanez, Primitivo; Morales Ruiz, Juan José (20180226)
Article
Restricted access  publisher's policyWe 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 (20150518)
Article
Open AccessCancer 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, ... 
Effective stability in reversible systems
Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás (1997)
Article
Open AccessIn this paper we present a procedure to put in normal form a nearlyintegrable reversible system, not necessarily a Hamiltonian system. Furthermore, nonresonant 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 (20170105)
Article
Restricted access  publisher's policyIt is known that hypercycles are sensitive to the socalled parasites and shortcircuits. While the impact of parasites has been widely investigated for wellmixed and spatial hypercycles, the effect of shortcircuits in ... 
Mixed dynamics in reversible maps with gure8 homoclinic connections
Delshams Valdés, Amadeu; Gonchenko, Sergey; Lázaro Ochoa, José Tomás (2014)
Conference report
Open AccessWe study dynamics and bifurcations of twodimensional reversible maps having nontransversal heteroclinic cycles containing symmetric saddle periodic points. We consider oneparameter families of rev ersible maps unfolding ... 
Mixed dynamics of twodimensional 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, 201809)
Article
Restricted access  publisher's policyWe study dynamics and bifurcations of 2dimensional reversible maps having a symmetric saddle fixed point with an asymmetric pair of nontransversal homoclinic orbits (a symmetric nontransversal homoclinic figure8). We ... 
On Normal Forms and Splitting of Separatrices in Reversible Systems
Lázaro Ochoa, José Tomás (Universitat Politècnica de Catalunya, 20031023)
Doctoral thesis
Open AccessÉs 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 (201203)
Article
Open Access 
On the integrability of polynomial fields in the plane by means of PicardVessiot theory
Lázaro Ochoa, José Tomás; Morales Ruíz, Juan José; Acosta Humánez, Primitivo Belén; Pantazi, Chara (20120112)
External research report
Open AccessWe 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 PicardVessiot theory
AcostaHumànez, Primitivo; Lázaro Ochoa, José Tomás; Morales Ruiz, Juan José; Pantazi, Chara (American Institute of Mathematical Sciences, 20150501)
Article
Open AccessWe 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 ... 
Pseudonormal form near saddlecenter or saddlefocus equilibria
Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás (2003)
Article
Open AccessIn this paper we introduce the pseudonormal 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 saddlecenter or a ... 
Pseudonormal forms and their applications
Delshams Valdés, Amadeu; Lázaro Ochoa, José Tomás (2001)
Article
Open Access 
Rational parameterizations approach for solving equations in some dynamical systems problems
Lázaro Ochoa, José Tomás; Gasull Embid, Armengol; Torregrosa Arús, Joan (201908)
Article
Restricted access  publisher's policyWe show how the use of rational parameterizations facilitates the study of the number of solutions of many systems of equations involving polynomials and square roots of polynomials. We illustrate the effectiveness of this ... 
Tesi doctoral: "On normal forms and splitting of separatrices in reversible systems"
Lázaro Ochoa, José Tomás (2003)
Working paper
Open Access 
Upper bounds for the number of zeroes for some Abelian integrals
Gasull Embid, Armengol; Lázaro Ochoa, José Tomás; Torregrosa, Joan (201209)
Article
Restricted access  publisher's policyConsider the vector field x′=−yG(x,y),y′=xG(x,y), where the set of critical points {G(x,y)=0} is formed by K straight lines, not passing through the origin and parallel to one or two orthogonal directions. We perturb it ...