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    • openAccess   Schoenberg coefficients and curvature at the origin of continuous isotropic positive definite kernels on spheres 

      Arafat, Ahmed; Gregori, Pablo; Porcu, Emilio Elsevier (2020)
      We consider the class Ψd of continuous functions that define isotropic covariance functions in the d-dimensional sphere Sd. We provide a new recurrence formula for the solution of Problem 1 in Gneiting (2013b), solved ...

    • openAccess   Schur spaces and weighted spaces of type H ∞ 

      Miralles Montolío, Alejandro Taylor & Francis (2012-11)
      We extend some results related to composition operators on Hv (G) to arbitrary linear operators on Hv0 (G) and Hv (G). We also give examples of rank-one operators on Hv(G) which cannot be approximated by composition operators

    • openAccess   Second Maximal Invariant Subgroups and Solubility of Finite Groups 

      shao, Changguo; Beltrán, Antonio Springer (2022-11-22)
      Let G be a finite group and assume that a group of automorphisms A is acting on G such that A and G have coprime orders. We prove that the fact of imposing specific properties on the second maximal A-invariant subgroups ...

    • closedAccess   Second-order analysis of anisotropic spatiotemporal point process data 

      Comas Rodríguez, Carlos; Rodríguez-Cortés, Francisco Javier; Mateu, Jorge Wiley (2015-02)
      Second-order orientation methods provide a natural tool for the analysis of spatial point process data. In this paper, we extend to the spatiotemporal setting the spatial point pair orientation distribution function. The ...

    • openAccess   Second-order and local characteristics of network intensity functions 

      Eckardt, Matthias; Mateu, Jorge Springer (2021)
      The last decade has witnessed an increase of interest in the spatial analysis of structuredpoint patterns over networks whose analysis is challenging because of geometricalcomplexities and unique methodological problems. ...

    • openAccess   Second-order preserving point process permutations 

      Mohler, George; Mateu, Jorge Wiley (2023)
      While random permutations of point processes are useful for generating counterfactuals in bivariate interaction tests, such permutations require that the underlying intensity be separable. In many real-world datasets where ...

    • openAccess   Seeking Darboux polynomials 

      Ferragut, Antoni; Gasull i Embid, Armengol Springer (2015-10)
      We introduce several techniques which allow to simplify the expression of the cofactor of Darboux polynomials of polynomial differential systems in Rn. We apply these techniques to some well-known systems when n=2,3,4. We ...

    • openAccess   Seguridad clínica del método madre canguro en pacientes pediátricos hospitalizados en la unidad de cuidados intensivos 

      González Ruiz, Miriam; Valero Cardona, Antonia; Castelló Benavent, Joaquín Ediciones ROL (2018)
      INTRODUCCIÓN. La literatura existente en el campo del Método Madre Canguro (MMC) ofrece resultados contradictorios sobre las modificaciones que sufre cada constante vital mientras este se practica. OBJETIVO. El presente ...

    • closedAccess   Self-duality in the class of precompact groups 

      Tkachenko, Mikhail Elsevier (2009)
      A topological Abelian group G is called (strongly) self-dual if there exists a topological isomorphism Φ : G → G<sup>∧</sup> of G onto the dual group G<sup>∧</sup> (such that Φ (x) (y) = Φ (y) (x) for all x, y ∈ G). We ...

    • closedAccess   Self-exciting point process modelling of crimes on linear networks 

      D'ANGELO, Nicoletta; Payares García, David Enrique; adelfio, giada; Mateu, Jorge SAGE Publications (2022)
      Although there are recent developments for the analysis of first and second-order characteristics of point processes on networks, there are very few attempts in introducing models for network data. Motivated by the analysis ...

    • closedAccess   Semi-analytical integration algorithms based on the use of several kinds of anomalies as temporal variable 

      López Ortí, José Antonio; Martínez Usó, María José; Marco Castillo, Francisco José Elsevier (2008)
      One of the main problems in celestial mechanics is the management of long developments in Fourier or Poisson series used to describe the perturbed motion in the planetary system. In this work we shall develop a software ...

    • closedAccess   Semiotic Vision of Ideologies 

      Nescolarde Selva, Josué Antonio; Usó Doménech, Josep Lluís Springer (2014)
      A semiotic theory of systems derived from language would have the purpose of classifying all the systems of linguistic expression: philosophy, ideology, myth, poetry, art, as much as the dream, lapsus, and free association ...

    • closedAccess   Sentiment dynamics and stoc returns: the case of the German stock market 

      Lux, Thomas Springer (2011-12)
      We use weekly survey data on short-term and medium-term sentiment of German investors in order to study the causal relationship between investors’ mood and subsequent stock price changes. In contrast to extant literature ...

    • openAccess   Sequentially compact subsets and monotone functions: An application to fuzzy theory 

      Font, Juan J.; Sanchis López, Manuel Elsevier (2015-09)
      Let (X,<,τO) be a first countable compact linearly ordered topological space. If (Y,D) is a uniform sequentially compact linearly ordered space with weight less than the splitting number s, then we characterize the ...

    • openAccess   Series expansions among weighted Lebesgue function spaces and applications to positive definite functions on compact two-point homogeneous spaces 

      Simões Barbosa, Victor; Gregori, Pablo; Peron, Ana P.; Porcu, Emilio Elsevier Inc. (2022-07-11)
      Geodesically isotropic positive definite functions on compact two-point homogeneous spaces of dimension d have series representation as members of weighted Lebesgue spaces Lw 1 ([−1, 1]), where the weight w(x) = wα,β(x) ...

    • openAccess   Seshadri-type constants and Newton-Okounkov bodies for non-positive at infinity valuations of Hirzebruch surfaces 

      Galindo, Carlos; Monserrat, Francisco; Moreno Ávila, Carlos Jesús Taylor and Francis (2023-02-01)
      We consider flags E• = {X ⊃ E ⊃ {q}}, where E is an exceptional divisor defining a non-positive at infinity divisorial valuation νE of a Hirzebruch surface Fδ , q a point in E and X the surface given by νE , and determine ...

    • openAccess   Shape Descriptors for classification of functional data 

      Epifanio, Irene American Statistical Association (2008)
      Curve discrimination is an important task in engineering and other sciences. We propose several shape descriptors for classifying functional data, inspired by form anal- ysis from the image analysis eld: statistical ...

    • openAccess   Sharp values for the constants in the polynomial Bohnenblust-Hille inequality 

      Jiménez-Rodríguez, P.; Muñoz-Fernández, G. A.; murillo arcila, marina; Seoane Sepúlveda, Juan Taylor & Francis (2016)
      In this paper we prove that the complex polynomial Bohnenblust–Hille constant for 2-homogeneous polynomials in ℂ2 is exactly 4√3/2. We also give the exact value of the real polynomial Bohnenblust–Hille constant for ...

    • closedAccess   Simplicity of normal subgroups and conjugacy class sizes 

      Beltrán, Antonio; Felipe, Maria José Springer (2013)
      Given a finite group G which possesses a non-abelian simple normal subgroup N having exactly four G -class sizes, we prove that N is isomorphic to PSL (2,2a) with a≥2 . Thus, we obtain an extension for normal subgroups of ...

    • openAccess   Singular perturbations of Blaschke products and connectivity of Fatou components 

      Canela, Jordi American Institute of Mathematical Sciences (AIMS) (2017)
      The goal of this paper is to study the family of singular perturbations of Blaschke products given by Ba,λ(z)=z3z−a1−a¯z+λz2. We focus on the study of these rational maps for parameters a in the punctured disk D∗ and |λ| ...