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    • closedAccess   Restrictions on maximal invariant subgroups implying solvability of finite groups 

      Beltrán, Antonio; shao, Changguo Springer Verlag (2018)
      Suppose that G and A are finite groups such that A acts coprimely on G via automorphisms. It is interesting to investigate the structure and properties of G when we impose some restrictions on its maximal A-invariant ...

    • openAccess   Revisiting Male Allies in Mathematics and Physics Throughout History: Role Models for Men in STEM Education 

      Calvo Iglesias, Encina; Epifanio, Irene MDPI (2024-05-16)
      In the academic world, there are also gender inequalities, which are especially visible in certain masculinized STEM areas, such as physics and mathematics. An essential factor in correcting these inequalities is the ...

    • closedAccess   Revisiting the random shift approach for testing in spatial statistics 

      Mrkvicka, Tomas; Dvořák, Jiří; González, Jonatan A.; Mateu, Jorge Elsevier (2020)
      We consider the problem of non-parametric testing of independence of two components of a stationary bivariate spatial process. In particular, we revisit the random shift approach that has become the standard method for ...

    • openAccess   Robust archetypoids for anomaly detection in big functional data 

      Vinue, Guillermo; Epifanio, Irene Springer (2020-08-03)
      Archetypoid analysis (ADA) has proven to be a successful unsupervised statistical technique to identify extreme observations in the periphery of the data cloud, both in classical multivariate data and functional data. ...

    • openAccess   Robust multivariate and functional archetypal analysis with application to financial time series analysis 

      Moliner Moliner, Jesús; Epifanio, Irene Elsevier (2018-12)
      Archetypal analysis approximates data by means of mixtures of actual extreme cases (archetypoids) or archetypes, which are a convex combination of cases in the data set. Archetypes lie on the boundary of the convex hull. ...

    • openAccess   Runge–Kutta–Nyström symplectic splitting methods of order 8 

      Blanes, Sergio; Casas, Fernando; Escorihuela-Tomàs, Alejandro Elsevier (2022-12)
      Different families of Runge–Kutta–Nyström (RKN) symplectic splitting methods of order 8 are presented for second-order systems of ordinary differential equations and are tested on numerical examples. They show a better ...

    • 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 ...