Ciencias,UNAM

Browsing Matemáticas by Submit Date

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Browsing Matemáticas by Submit Date

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  • Complete hypersurfaces in R2n+2 with constant negative 2n-th curvature
    Palmas, O (2003)
    We use equivariant geometry methods to show the existence of complete hypersurfaces in euclidean spaces with constant negative 2n-th curvature.
  • Adjunction spaces and unions of G-ANE's
    Elfving, E; Mata-Romero, A; Antonyan, SA (2002)
    Let G be a locally compact Hausdorff group. We study adjunction spaces and unions of equivariant absolute neighborhood extensors (G-ANE's) in the category of all proper G-spaces that axe metrizable by G-invariant metrics. ...
  • A qualitative model of a motor circadian rhythm
    Fuentes-Pardo, B; Guzman-Gomez, AM; Lara-Aparicio, M; de Medrano, SL (2003)
    In Nature it is possible to observe diverse rhythms. Because of their adaptive characteristics, the circadian rhythms are of major importance and have been the subject of numerous experimental and theoretical studies. In ...
  • Asymptotic properties of two interacting maps
    Ble, G; Castellanos, V; Falconi, MJ (2003)
    In this paper we consider a system whose state x changes to sigma(x) if a perturbation occurs at the time t, for t > 0, t is not an element of N. Moreover, the state x changes to the new state eta(x) at time t, for t is ...
  • Natural classes, left exact preradicals, and flat epimorphisms
    Rincon-Mejia, HA; Ríos-Montes, J; Alvarado, A (2003)
    We define a function between the lattice of left exact preradicals in R-mod and the complete boolean lattice R-nat of natural classes in R-mod in such a way that the image of this function results to be a complete sublattice ...
  • Conditional weak laws in Banach spaces
    Meda-Guardiola, Ana (2003)
    Let (B, parallel to . parallel to) be a separable Banach space. Let Y, Y-1, Y-2,... be centered i.i.d. random vectors taking values on B with law mu, mu(.) = P(Y is an element of .), and let S-n = Sigma(i=1)(n) Y-i. Under ...
  • Invariant pseudometrics on Palais proper G-spaces
    de Neymet, S; Antonyan, SA (2003)
    Let G be a locally compact Hausdorff group. It is proved that: (1) on each Palais proper G-space X there exists a compatible family of Ginvariant pseudometrics
  • Some dynamical properties of mappings defined on Knaster continua
    Mendez-Lango, H (2002)
    We present an arc-like continuum X and a mapping f : X --> X with the following properties: The set of recurrent points of f is dense in X
  • A study of the dynamics of lambda sin z
    Dominguez, P; Sienra, G (2002)
    This paper studies the dynamics of the family lambda sin z for some values of lambda. First we give a description of the Fatou set for values of lambda inside the unit disc. Then for values of lambda on the unit circle of ...
  • Triggered alternans in an ionic model of ischemic cardiac ventricular muscle
    Arce, H; Guevara, MR; López, A (2002)
    It has been known for several decades that electrical alternans occurs during myocardial ischemia in both clinical and experimental work. There are a few reports showing that this alternans can be triggered into existence ...
  • Fractal scattering of microwaves from soils
    Oleschko, K; Korvin, G; Balankin, AS; Khachaturov, RV; Flores, L; Figueroa, B; Urrutia, J; Brambila, F (2002)
    Using a combination of laboratory experiments and computer simulation we show that microwaves reflected from and transmitted through soil have a fractal dimension correlated to that of the soil's hierarchic permittivity ...
  • Umbilicity of surfaces with orthogonal asymptotic lines in R-4
    Romero-Fuster, MD; Sánchez-Bringas, F (2002)
    We study some properties of surfaces in 4-space all whose points are umbilic with respect to some normal field. In particular, we show that this condition is equivalent to the orthogonality of the (globally defined) fields ...
  • Travelling waves in a nonlinear degenerate diffusion model for bacterial pattern formation
    Satnoianu, RA; Maini, PK; Garduno, FS; Armitage, JP (2001)
    We study a reaction diffusion model recently proposed in [5] to describe the spatiotemporal evolution of the bacterium Bacillus subtilis on agar plates containing nutrient. An interesting mathematical feature of the model, ...
  • The lattice structure of preradicals
    Raggi, F; Montes, JR; Rincon, H; Fernandez-Alonso, R; Signoret, C (2002)
    In this paper we study the lattice of all preradicals on a ring R. We describe this lattice, we prove that it is an atomic and coatomic lattice and we describe the atoms and coatoms. We also give characterizations of simple ...
  • Rates of convergence for the Nummelin conditional weak law of large numbers
    Kuelbs, J; Meda-Guardiola, Ana (2002)
    Let (B, parallel to . parallel to) be a real separable Banach space of dimension 1 less than or equal to d less than or equal to infinity, and assume X,X-1, X-2,... are i.i.d. B valued random vectors with law mu=L(X) and ...
  • Universal proper G-spaces
    Antonyan, SA (2002)
    It is proved that: (1) every Lie group G can act properly (in sense of Palais) on each infinite-dimensional Hilbert space 12 (T) of a given weight tau such that (G, l(2) (tau)) becomes a universal G-space for all metrizable ...
  • Infinity manifolds of cubic polynomial Hamiltonian vector fields with 2 degrees of freedom
    Falconi, M; Lacomba, EA; Llibre, J (2000)
    Let X be the Hamiltonian vector field with two degrees of freedom associated to the cubic polynomial Hamiltonian H(x,y,z,w). Using the Poincare compactification we show that all the energy levels of X in R-4 reach the ...
  • On compact weaker topologies in function spaces
    Casarrubias-Segura, F (2001)
    In this paper we prove that for every cardinal kappa, the space C-p(D-k) admits a continuous bijection onto a space whose all finite powers are Lindelof (the symbol D stands for the discrete two-point space). We also prove ...
  • On the firing maps of a general class of forced integrate and fire neurons
    Carrillo, H; Ongay, FA (2001)
    Integrate and fire processes are fundamental mechanisms causing excitable and oscillatory behavior. Van der Pol [Philos. Mag. (7) 2 (11) (1926) 978] studied oscillations caused by these processes, which he called,relaxation ...
  • On the lattices of natural and conatural classes in R-mod
    Rincon, H; Montes, JR; García, AA (2001)

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